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Section 2 Watershed Description 2

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Section 2 Watershed Description 2.1 Watershed description - Lake Area: 570 acres or 230 hectares - Watershed Area: 13 square miles or 3,367 Hectares - General Description: - The Pine River Pond is located in Wakefield, Carroll County, in eastern New Hampshire. - Development: The pond is the water source for the people living in this region. - Several boat launches are located around the pond which are the source of a ton of run-off - As a result of the early farming practices in this area, Pine River Pond has been transformed and developed from its previous form. - The soil cover in this region is adapted to provide excellent support for grazing activities for animals such as goats, cows, and horses (Project Partners, 2017). - The Pine River is located at the beginning of the Pine River, which travels in a northwest direction into Ossipee Lake. It also is connected to the Saco River Watershed. -Has one dam known as the Arthur Fox Dam that maintains the water level, this is done to prevent any damage to the shorelines and prevent flooding in the area. The water height fluctuates 8 feet when the yearly drawdown occurs in the winter. The State of New Hampshire controls the dam. -Infrastructure: Agricultural businesses around Pine River Pond. - Goods produced include peanut butter, ovens, breweries, and maple syrup goods - There is not too much residential and commercial development. - There are also no paved roads, all roads are gravel - Both seasonal and year-round homes located around the pond - Fish Species: Some of the species of fish that are in the lake include the Largemouth Bass, Smallmouth Bass, and Chain Pickerel. - In terms of Pond River conservation, there is the Action Wakefield Watersheds Alliance (AWWA) Youth Conservation Corps (YCC), whose mission is to help develop projects to mitigate erosion and teach those who own homes how they can avoid pollution in the form of runoff. -The AWWA also is focused on fixing the roads near the Pine River - culverts are failing and collapsing into the water and preventing the flow from going through Reference: https://www.pca.state.mn.us/sites/default/files/wq-ws4-33a.pdf https://pineriverpond.org/about/ https://awwatersheds.org/pine-river-pond/ 2.2 Physical Characteristics - Pond stats: - The pond has an area of 570 acres and a volume of 8,547,500 m3. - The shoreline extends a little over 12 miles and has an elevation of 584 ft. - Has a flushing rate of 2.2 flushes/year. - Average depth is 15 feet, with a maximum of 55 feet. - There are 15 islands located throughout the pond. - flows Northwest - Forest Area: -The Pine River area's significant land cover is dominated by forest, accounting for 71% of the total land cover. - Agricultural Land -The agricultural land also forms a substantial part of the land since it consumes around 13% of the total land area; this is attributed to the high number of farmers in the area. -10% of the land cover is occupied by surface water and wetlands, the transportation and the developed land accounts for 6% of the land remaining in the Pine River (Project Partners, 2017). -The Pine River Pond’s water provides nutrition values for the people living in the area and the plants and other organisms present in the ecosystem. - Roadways; Two main highways, routes 16 and 153, are close by on the southern parts of the pond. Reference: https://www.pca.state.mn.us/sites/default/files/wq-ws4-33a.pdf https://www.google.com/maps/place/Pine+River+Pond/@43.6325537,71.0409318,14z/data=!3m1!4b1!4m5!3m4!1s0x4cb2df379a34a497:0x1b3e0611765199e1!8m2! 3d43.6282163!4d-71.0274492 2.2.1 Surficial Geology ? The lake’s substrate is made up of mostly a mix of rock and sand with some limited areas of organic matter or muck. 2.2.2 Soil Erosion Potential ? Soil Hydraulic Group (highest percentage of A&B which means soil is likely to erode) - References: - https://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm 2.3 Population ? Wakefield (location of Pine River Pond) 129.3 persons per square mile of land area ? Ossipee (majority of watershed) 61.8 persons per square mile of land area ? Effingham (encompasses part of watershed) 38.0 persons per square mile of land area Combined population of both Ossipee and Wakefield went from 9423 in 2010 to 9494 in 2019. There was a much larger population increase from the years 1970 to 2019 where their combined populations went from 3076 to 9494. - References: - https://www.nhes.nh.gov/elmi/products/cp/profiles-pdf/wakefield.pdf - https://www.nhes.nh.gov/elmi/products/cp/profiles-pdf/ossipee.pdf - https://www.nhes.nh.gov/elmi/products/cp/profiles-pdf/effingham.pdf 2.4 Land Cover In the Pine River pond watershed, it was found that in 2010 Wakefield New Hampshire 843 acres of impervious cover or 3.3% of the total land area in the town. In 2005 it was found that Ossipee New Hampshire had 3427 acres of developed land, or about 7% of its total land area was developed. https://www.nhes.nh.gov/elmi/products/cp/profiles-htm/wakefield.htm https://scholars.unh.edu/cgi/viewcontent.cgi?article=1397&context=prep 2.5 Lake Morphology and Morphometry Pine River Pond's size extends to 570-acre around (2.3km2) in Carroll County, eastern New Hampshire. The Pine River Pond is situated in Wakefield town (Pine, n.d.). The Arthur Fox Dam is responsible for an 8 foot fluctuation in water height when the drawback occurs annually each winter, which accounts for a change in the shoreline. Reference: https://pineriverpond.org/about/ SQUAM LAKES Watershed Management Plan December 2019 Amended -- February 2020 SQUAM LAKES | WATERSHED MANAGEMENT PLAN SQUAM LAKES Watershed Management Plan Prepared by the SQUAM LAKES ASSOCIATION In cooperation with FB Environmental Associates and the New Hampshire Department of Environmental Services December 2019 Amended -- February 2020 CONTACT Squam Lakes Association 534 US Route 3 Holderness, NH 03245 www.squamlakes.org Funding for this project was provided in part by a Watershed Assistance Grant from the NH Department of Environmental Services with Clean Water Act Section 319 funds from the U.S. Environmental Protection Agency. FB Environmental Associates (FBE) assisted the Squam Lakes Association with the plan development process, including conducting the watershed survey and pollutant load reduction estimates, reviewing water quality analysis and water quality goal documentation, reviewing model setup and results, presenting final results at a public meeting, and reviewing the final watershed management plan. SQUAM LAKES ASSOCIATION i SQUAM LAKES | WATERSHED MANAGEMENT PLAN Acknowledgements Steering Committee ? ? ? ? ? ? ? ? Bob Snelling (Holderness Planning Board, SLA water quality monitoring volunteer) Dave Martin (SLA water quality monitoring volunteer, shorefront property owner) Andrea LaMoreaux (NH Lakes Association) Jeff Hayes (Lakes Region Planning Commission) Tiffany Grade (Loon Preservation Committee) June Hammond Rowan (Plymouth State University) Peter Webster (shorefront property owner) Cindy O’Leary (SLA board member, shorefront property owner) Water Quality Advisory Committee ? ? ? ? ? ? ? ? ? ? Bob Snelling (Holderness Planning Board, SLA water quality monitoring volunteer) Dave Martin (SLA water quality monitoring volunteer, shorefront property owner) David Cutright (SLA water quality monitoring volunteer, shorefront property owner) Wendy Waskin (NHDES) Matt Wood (NHDES) Mark Green (Plymouth State University) Bob Craycraft (UNH Lakes Lay Monitoring Program) Leigh Sharps (Ashland Selectboard) Susan McLeod (Ashland Planning Board) Charley Hanson (Center Harbor Planning Board) Technical Staff/Reviewers: ? ? ? ? ? ? ? ? ? ? Forrest Bell (Owner, FB Environmental Associates) Laura Diemer (Environmental Monitoring Division Lead, FB Environmental Associates) Christine Bunyon (Project Scientist I, FB Environmental Associates) Audrey Eisenhauer (Squam Lakes Natural Science Center) Woody Thompson Wendy Waskin (NHDES) Matt Wood (NHDES) Steve Landry (NHDES) Barbara McMillan (NHDES) Kirsten Nelson (NHDES) Special Thanks To: ? ? ? ? ? ? Watershed towns (Ashland, Center Harbor, Holderness, Moultonborough, Sandwich) Plymouth State University (Mark Green, Joe Boyer, and June Hammond Rowan) SLA water quality monitors (since 1979) SLA Board, staff, and volunteers UNH Lakes Lake Monitoring Program (Bob Craycraft and Jeff Schloss) Lakes Region Planning Commission (Jeff Hayes, Susan Slack, and Dave Jeffers) SQUAM LAKES ASSOCIATION ii SQUAM LAKES | WATERSHED MANAGEMENT PLAN Table of Contents Acknowledgements .................................................................................................................................................... ii List of Tables ............................................................................................................................................................... v List of Figures ............................................................................................................................................................ vii List of Abbreviations ................................................................................................................................................ viii Definitions ................................................................................................................................................................. ix 1. 2. 3. Introduction & Vision ...................................................................................................................................... 11 1.1 Background and Purpose......................................................................................................................... 11 1.2 Vision ....................................................................................................................................................... 11 1.3 Statement of Goal ................................................................................................................................... 12 1.4 Incorporating EPA’s Nine Elements ......................................................................................................... 13 1.5 Public Engagement and Community Involvement .................................................................................. 13 1.6 Current and Historic Efforts in the Squam Watershed............................................................................ 15 The Squam Lakes Watershed .......................................................................................................................... 17 2.1 Watershed description ............................................................................................................................ 17 2.2 Physical Characteristics ........................................................................................................................... 18 2.2.1 Surficial Geology .............................................................................................................................. 18 2.2.2 Soil Erosion Potential ....................................................................................................................... 18 2.3 Population ............................................................................................................................................... 19 2.4 Land Cover ............................................................................................................................................... 19 2.5 Lake Morphology and Morphometry ...................................................................................................... 19 Water Quality Assessment .............................................................................................................................. 20 3.1 Water Quality and Assimilative Capacity Analysis .................................................................................. 20 3.1.1 Analysis Design and Methods .......................................................................................................... 20 3.1.2 Water Quality Criteria ..................................................................................................................... 20 3.1.3 Squam Lake Water Quality .............................................................................................................. 21 3.1.4 Little Squam Lake Water Quality ..................................................................................................... 23 3.1.5 Assimilative Capacity ....................................................................................................................... 24 3.1.6 Dissolved Oxygen and Hypolimnion Total Phosphorus ................................................................... 25 3.1.7 Cyanobacteria .................................................................................................................................. 26 3.2 Buildout analysis ...................................................................................................................................... 27 3.3 Watershed Modeling ............................................................................................................................... 27 3.3.1 Watershed and Sub-basin Delineation ............................................................................................ 27 SQUAM LAKES ASSOCIATION iii SQUAM LAKES | WATERSHED MANAGEMENT PLAN 3.3.2 Land Cover Update .......................................................................................................................... 28 3.3.3 Other LLRM Inputs ........................................................................................................................... 29 3.3.4 Model limitations ............................................................................................................................ 29 3.3.5 Calculating Pre-Development Phosphorus Loads ........................................................................... 30 3.3.6 Calculating Future Phosphorus Loads ............................................................................................. 30 3.3.7 Results (Current, Pre-Development, and Future Load Estimates) .................................................. 30 3.4 3.4.1 Pollutant Load Reductions Needed ................................................................................................. 34 3.4.2 Finalizing the Water Quality Goal .................................................................................................... 36 3.5 4. 5. 6. Water Quality Goal .................................................................................................................................. 34 Pollutant Source Identification—Watershed Survey .............................................................................. 37 Watershed Management ................................................................................................................................ 37 4.1 Structural Strategies ................................................................................................................................ 37 4.2 Non-Structural Strategies ........................................................................................................................ 38 4.3 Adaptive Management Approach ........................................................................................................... 38 Plan Implementation ....................................................................................................................................... 39 5.1 Plan oversight .......................................................................................................................................... 39 5.2 Action Plan............................................................................................................................................... 40 5.3 Indicators to Measure Progress and Success .......................................................................................... 48 5.3.1 Environmental Indicators ................................................................................................................ 48 5.3.2 Programmatic Indicators ................................................................................................................. 49 5.3.3 Social Indicators ............................................................................................................................... 50 5.4 Estimated Technical Assistance and Costs Needed................................................................................. 50 5.5 Education ................................................................................................................................................. 51 References ....................................................................................................................................................... 51 Appendix: Watershed Survey Results/Memorandum SQUAM LAKES ASSOCIATION iv SQUAM LAKES | WATERSHED MANAGEMENT PLAN List of Tables Table 1-1: Watershed management plan steering committee members and affiliations. ..................................... 12 Table 1-2: Water quality advisory committee members and affiliations................................................................ 12 Table 3-1: Trophic state water quality criteria in New Hampshire. ........................................................................ 20 Table 3-2. Decision matrix for aquatic life use (ALU) assessment in New Hampshire. TP = total phosphorus. Chl-a = chlorophyll-a, a surrogate measure for algae concentration. .............................................................................. 21 Table 3-3: Squam Lake summary statistics for epilimnetic total phosphorus, epilimnetic chlorophyll-a, and Secchi disk transparency during the summer season (May 24-September 15). Trends were determined using the MannKendall trend analysis test. ..................................................................................................................................... 21 Table 3-4: Little Squam Lake summary statistics for epilimnetic total phosphorus, epilimnetic chlorophyll-a, and Secchi disk transparency during the summer season (May 24-September 15). Trends were determined using the Mann-Kendall trend analysis test. ........................................................................................................................... 23 Table 3-5: NH surface water classification assessment criteria. ............................................................................. 25 Table 3-6: Assimilative capacity, reserve assimilative capacity, remaining assimilative capacity, and waterbody classification for total phosphorus and chlorophyll-a in Squam Lake and Little Squam Lake. ............................... 25 Table 3-7: Date and depth of anoxic conditions in Squam Lake water quality testing sites. .................................. 26 Table 3-8: Date and depth of anoxic conditions in Little Squam Lake water quality testing sites.......................... 26 Table 3-9: Summary of land area, water flow, and total phosphorus (TP) loading by sub-basin the Squam Lake watershed. ............................................................................................................................................................... 31 Table 3-10: Phosphorus load estimates from the Lake Loading Response Model (kg/ha/yr) for Squam Lake. ..... 32 Table 3-11: Predicted and Measured in-lake total phosphorus (TP) concentrations for Squam Lake. Measured values are increased by 20% as an estimate for year-round in-lake phosphorus concentrations ......................... 32 Table 3-12: Summary of land area, water flow, and total phosphorus (TP) loading by sub-basin the Little Squam Lake watershed. ...................................................................................................................................................... 33 Table 3-13: Load estimates from the Lake Loading Response Model (kg/ha/year) for Little Squam Lake. ............ 33 Table 3-14: Predicted and measured in-lake total phosphorus concentrations. Measured values are increased by 20% as an estimate for year-round in-lake phosphorus concentrations ................................................................ 34 Table 3-15: Total phosphorus loading (kg/yr) reductions necessary to achieve water quality goal. ..................... 34 Table 3-16: Shoreline property total phosphorus (TP) reductions. Based on Region 5 model bank stabilization estimate for silt loams, using 100 ft (length) by 5 ft (height) and moderate lateral recession rate of 0.2 ft/yr and assuming a 50% BMP efficiency for high impact properties and using 50 ft (length) by 3 ft (height) and moderate lateral recession rate of 0.1 ft/yr and assuming a 50% BMP efficiency for medium impact properties. ............... 35 Table 3-17: Total phosphorus (TP) loading reductions from septic system improvements. .................................. 35 Table 3-18: Proposed timeline for total phosphorus (TP) loading reduction. ........................................................ 37 Table 5-1: Action Plan for the Squam Lakes Watershed Management Plan........................................................... 41 Table 5-2: Environmental indicators for the Squam Lakes. Benchmarks are cumulative across years. ................. 48 Table 5-3: Programmatic indicators for the Squam Lakes. Benchmarks are cumulative across years. .................. 49 Table 5-4: Social indicators for the Squam Lakes. Benchmarks are cumulative across years................................. 50 SQUAM LAKES ASSOCIATION v SQUAM LAKES | WATERSHED MANAGEMENT PLAN Table 5-5: Estimate of costs for implementing the Squam Lakes Watershed Management Plan. ......................... 50 SQUAM LAKES ASSOCIATION vi SQUAM LAKES | WATERSHED MANAGEMENT PLAN List of Figures Figure 2-1: Map of the Squam Lake and Little Squam Lake Watersheds and their sub-basins. Cross-hatched areas are direct shoreline input. Red dots indicate water quality monitoring sites. LS West (in Little Squam Lake) and Deephaven (in Squam Lake) are the deepest points in each lake. ......................................................................... 17 Figure 3-1: Annual median epilimnetic total phosphorus for the deep spot of Squam Lake, 1982-2017. Gaps reflect years with no data........................................................................................................................................ 22 Figure 3-2: Annual median epilimnetic chlorophyll-a for the deep spot of Squam Lake, 1982-2017 .................... 22 Figure 3-3: Annual average Secchi disk transparency for the deep spot of Squam Lake, 1982-2017. Gaps reflect years with no data. .................................................................................................................................................. 22 Figure 3-4: Annual median epilimnetic total phosphorus for the deep spot of Little Squam Lake, 1980-2017. Gaps reflect years with no data........................................................................................................................................ 23 Figure 3-5: Annual median epilimnetic chlorophyll-a for the deep spot of Little Squam Lake, 1979-2017. .......... 24 Figure 3-6: Annual average Secchi disk transparency for the deep spot of Little Squam Lake, 1979-2017. .......... 24 Figure 3-7: Land cover in the Squam Lakes Watershed after correcting existing land cover files.......................... 28 Figure 3-8: Land cover summary for the Squam Lake and Little Squam Lake. ....................................................... 31 Figure 3-9: Phosphorus load summary from the Lake Loading Response Model for Squam Lake. The relative contribution of septic systems greatly increases in the future model scenario (due to the large number of potential new buildings) and thus lowers the proportional loads from the watershed, atmospheric deposition, and waterfowl, but all loads (except waterfowl) greatly increase in load from the current model scenario. ....... 32 Figure 3-10: Phosphorus load summary from the Lake Loading Response Model for Little Squam Lake. The relative contribution of septic systems greatly increases in the future model scenario (due to the large number of potential new buildings) and thus lowers the proportional loads from Squam Lake and waterfowl, but all loads (except waterfowl) greatly increase in load from the current model scenario. ..................................................... 33 SQUAM LAKES ASSOCIATION vii SQUAM LAKES | WATERSHED MANAGEMENT PLAN List of Abbreviations ACRONYM ALU BMP CHL-A CWA DO EMD FBE LID LLMP LLRM LRPC NCEI NH GRANIT NHD NHDES NHDOT NHFGD NPS NWI PCR ppb, ppm SDT SLA TP USEPA DEFINITION Aquatic Life Use Best Management Practices Chlorophyll-a Clean Water Act Dissolved Oxygen Environmental Monitoring Database FB Environmental Associates Low Impact Development UNH Lakes Lay Monitoring Program Lake Loading Response Model Lakes Region Planning Commission National Centers for Environmental Information New Hampshire Geographically Referenced Analysis and Information Transfer System (NH GIS Clearinghouse) National Hydrography Dataset New Hampshire Department of Environmental Services New Hampshire Department of Transportation New Hampshire Fish and Game Department Nonpoint Source Pollution National Wetlands Inventory Primary Contact Recreation parts per billion, parts per million Secchi Disk Transparency Squam Lakes Association Total Phosphorus United States Environmental Protection Agency SQUAM LAKES ASSOCIATION viii SQUAM LAKES | WATERSHED MANAGEMENT PLAN Definitions Adaptive management approach recognizes that the entire watershed cannot be restored with a single restoration action or within a short time frame. The approach provides an iterative process to evaluate restoration successes and challenges to inform the next set of restoration actions. Anoxia is a condition of low dissolved oxygen. Areal water load is a term used to describe the amount of water entering a lake on an annual basis divided by the lake’s surface area. Assimilative Capacity is a lake’s capacity to receive and process nutrients (phosphorus) without impairing water quality or harming aquatic life. Best Management Practices (BMPs) are conservation practices designed to minimize discharge of NPS pollution from developed land to lakes and streams. Management plans should include both non-structural (nonengineered) and structural (engineered) BMPs for existing and new development to ensure long-term restoration success. Build-out analysis combines projected population estimates, current zoning restrictions, and a host of additional development constraints (conservation lands, steep slope and wetland regulations, existing buildings, soils with low development suitability, and unbuildable parcels) to determine the extent of buildable areas in the watershed. Chlorophyll-a (Chl-a) is a measurement of the green pigment found in all plants, including microscopic plants such as algae. Measured in parts per billion or ppb, it is used as an estimate of algal biomass; the higher the Chla value, the higher the amount of algae in the lake. Clean Water Act (CWA) requires states to establish water quality standards and conduct assessments to ensure that surface waters are clean enough to support human and ecological needs. Cyanobacteria are photosynthetic, nitrogen-fixing bacteria that can grow prolifically as blooms when enough nutrients are available. Some cyanobacteria can produce microcystin, which is highly toxic to humans and other life forms. Dissolved Oxygen (DO) is a measure of the amount of oxygen dissolved in water. Low oxygen can directly kill or stress organisms and stimulate release phosphorus from bottom sediments. Epilimnion is the top layer of lake water directly affected by seasonal air temperature and wind. This layer is well-oxygenated by wind and wave action. Flushing rate (also called retention time) is the amount of time water spends in a waterbody. It is calculated by dividing the flow in or out by the volume of the waterbody. Full build-out refers to the time and circumstances in which, based on a set of restrictions (e.g., environmental constraints and current zoning), no more building growth can occur, or the point at which lots have been subdivided to the minimum size allowed. Hypolimnion is the bottom-most layer of the lake that experiences periods of low oxygen during stratification and is devoid of sunlight for photosynthesis. Impervious surfaces refer to any surface that will not allow water to soak into the ground. Examples include paved roads, driveways, parking lots, and roofs. Internal Phosphorus Loading is the process whereby phosphorus bound to lake bottom sediments is released back into the water column during periods of anoxia. The phosphorus can be used as fuel for plant and algae growth, creating a positive feedback to eutrophication. SQUAM LAKES ASSOCIATION ix SQUAM LAKES | WATERSHED MANAGEMENT PLAN Low Impact Development (LID) is an alternative approach to conventional site planning, design, and development that reduces the impacts of stormwater by working with natural hydrology and minimizing land disturbance by treating stormwater close to the source, and preserving natural drainage systems and open space, among other techniques. Nonpoint Source (NPS) Pollution comes from diffuse sources throughout a watershed, such as stormwater runoff, seepage from septic systems, and gravel road erosion. One of the major constituents of NPS pollution is sediment, which contains a mixture of nutrients (like phosphorus) and inorganic and organic material that stimulate plant and algae growth. Non-structural BMPs, which do not require extensive engineering or construction efforts, can help reduce stormwater runoff and associated pollutants through operational actions, such as land use planning strategies, municipal maintenance practices, and targeted education and training. Oligotrophic lakes are less productive or have less nutrients (i.e., low levels of phosphorus and chlorophyll-a), deep Secchi Disk Transparency readings (8.0 m or greater), and high dissolved oxygen levels throughout the water column. In contrast, eutrophic lakes have more nutrients and are therefore more productive and exhibit algal blooms more frequently than oligotrophic lakes. Mesotrophic lakes fall in-between with an intermediate level of productivity. Secchi Disk Transparency (SDT) is a vertical measure of the transparency of water (ability of light to penetrate water) obtained by lowering a black and white disk into the water until it is no longer visible. Structural BMPs, or engineered Best Management Practices, are often at the forefront of most watershed restoration projects and help reduce stormwater runoff and associated pollutants. Total Phosphorus (TP) is one of the major nutrients needed for plant growth. It is generally present in small amounts (measured in parts per billion (ppb)) and limits plant growth in lakes. In general, as the amount of TP increases, the amount of algae also increases. Trophic State is the degree of eutrophication of a lake and is designated as oligotrophic, mesotrophic, or eutrophic. SQUAM LAKES ASSOCIATION x SQUAM LAKES | WATERSHED MANAGEMENT PLAN 1. Introduction & Vision 1.1 Background and Purpose The Squam Lakes in central New Hampshire are an important part of the culture, economy, and environment of the neighboring communities of Ashland, Center Harbor, Holderness, Moultonborough, and Sandwich. The Lakes are renowned for their quiet beauty and clean waters by residents and visitors alike. With increasing pressure from development, especially the subdivision of large parcels of land, increased tourism, and threats from climate change, it is imperative to plan and manage for the future. The Squam Lakes Watershed faces a number of concerns today. Nutrient loading from the watershed, increased recreation activity, and invasive species all threaten to change the quality of water—and the quality of life in the lakes. Recent evidence identifying legacy contaminants in select areas in the watershed also may pose a concern for the health of the lakes. These issues can all be compounded by increasing development throughout the watershed and by climate change. A watershed management plan examines the factors affecting watershed health. It incorporates data on water quality and creates goals to maintain or improve watershed-wide standards. It acts as a guiding document for towns to support watershed and community health across municipal boundaries. Guided by the Squam Lakes Association (SLA), whose mission is to conserve and protect the Squam Watershed, the watershed planning process has been grounded in community collaboration. Conservation and protection work at the watershed scale requires productive collaboration across all aspects of a community; town governments, state agencies, conservation partners, universities, and local businesses, as well as the greater Squam community. All stakeholders are needed to ensure a healthy watershed into the future. A comprehensive watershed management plan for the Squam Lakes provides a strategy for protecting water quality into the future. The United States Environmental Protection Agency (EPA) requires an approved watershed-based plan to become eligible for Clean Water Act (CWA) Section 319 funds. Fund can be used for water quality improvement projects identified by watershed-based plans. The Squam Lakes Watershed Management Plan follows EPA guidelines and requirements that incorporate the nine key elements (a – i) for watershed-based plans. 1.2 Vision The watershed management plan development process was guided by a steering committee. Established in 2016, the steering committee comprised a diverse group of Squam stakeholders (Table 1-1). In the early stages of plan development, the steering committee was first tasked with developing a vision statement. Although the 1991 Squam Watershed Plan plan did not have a vision statement, the recommendations focused on maintaining the quality of the water in the lakes and encouraging watershed development in a manner that supports local communities without damaging the overall ecosystem. By spring 2016, interviews were conducted with a variety of watershed stakeholders, who provided major “themes” that the vision statement needed to address. The themes remained similar to the 1991 plan and centered on protecting the watershed, maintaining ecological integrity, preserving the character of the region, balancing high environmental quality with the benefits that humans derive from the watershed, and supporting and upholding the social and economic components of the Squam Lakes community. From this, a vision statement was drafted and presented to the public through an online forum where people could post comments about the statement. Additional comments were gathered from attendees at the 2016 Squam Lakes Association Annual Meeting. With this input, the following vision statement was created: SQUAM LAKES ASSOCIATION 11 SQUAM LAKES | WATERSHED MANAGEMENT PLAN The Squam Lakes Watershed is a unique and special place with clean water; a healthy ecosystem; a vibrant and supportive economy; sustainable land uses and development; and access for all in a manner that respects the carrying capacity of the watershed. Table 1-1: Watershed management plan steering committee members and affiliations. Committee Member Bob Snelling Dave Martin Andrea LaMoreaux Jeff Hayes Tiffany Grade June Hammond Rowan Peter Webster Cindy O’Leary Affiliation Holderness Planning Board, SLA water quality monitoring volunteer SLA water quality monitoring volunteer, shorefront property owner NH Lakes Association Lakes Region Planning Commission Loon Preservation Committee Plymouth State University Shorefront property owner SLA board member, shorefront property owner 1.3 Statement of Goal After establishing a vision statement, the steering committee recommended that a more focused group of water quality experts convene to establish the water quality goals and guide the completion of the watershed management plan. A Water Quality Advisory Committee was created in 2018 with representative stakeholders across the watershed (Table 1-2). Utilizing current and historic water quality data, future development projections, and current and future nutrient modelling results, the Water Quality Advisory Committee set the following water quality goals and required nutrient load prevention, reduction, and/or offset needed to achieve the goals for the Squam Lakes over the next ten years. See Section 3.3.2 for more information on this process. The goal of the Squam Lakes Watershed Management Plan is to maintain current in-lake median total phosphorus concentrations (6.5 ppb in Squam Lake and 6.4 ppb in Little Squam Lake). Based on development growth projections, this will require the prevention, reduction, and/or offset of 113 kg/year in phosphorus loading to the Squam Lakes over the next ten years. Table 1-2: Water quality advisory committee members and affiliations. Committee Member Bob Snelling Dave Martin David Cutright Wendy Waskin Matt Wood Mark Green Bob Craycraft Leigh Sharps Susan McLeod Charley Hanson Affiliation Holderness Planning Board, SLA water quality monitoring volunteer SLA water quality monitoring volunteer, shorefront property owner SLA water quality monitoring volunteer, shorefront property owner NHDES NHDES Plymouth State University University of New Hampshire Lakes Lay Monitoring Program Ashland Select Board, shorefront property owner Ashland Planning Board Center Harbor Planning Board SQUAM LAKES ASSOCIATION 12 SQUAM LAKES | WATERSHED MANAGEMENT PLAN 1.4 Incorporating EPA’s Nine Elements The EPA requires that watershed plans incorporate nine key elements. These nine elements are described below, along with the section locations for each of the elements in the Squam Lakes Watershed Management Plan. a. Identify pollution causes and sources: Section 3.5 describes the results of the watershed survey and summarizes the erosion hotspots that contribute sediment and nutrients to the lake. b. Estimate pollution reductions needed: Sections 3.4.1 and 3.4.2 describe the pollutant load reductions necessary to reach the water quality goal of maintaining current water quality in the Squam Lakes. c. Management measures that will achieve load reductions and targeted critical areas: Sections 4 and 5.2 describe the actions to be undertaken to meet the water quality goal established by the watershed management plan. d. Estimate amounts of technical and financial assistance and the relevant authorities needed to implement the watershed management plan: Sections 5.1, 5.2, and 5.4 describe costs, technical assistance needed, and those groups or individuals that will be responsible for completing action items. e. Develop an information/education component: Education, outreach, and communication are discussed in Sections 1.5, 5.2, and 5.5 f. Develop a project schedule: The project schedule is established in the Action Plan (Section 5.2). Each action item has a timeline of when completion should be expected. g. Describe the interim, measurable milestones: Section 5.3 describes the interim as well as final milestones indicating successful watershed management plan implementation. h. Identify indicators to measure progress: Sections 3.4 and 5.3 can be used to determine if loading reductions are being met over time indicating watershed management plan implementation is successful or on-track. i. Develop a monitoring component: Long-term monitoring in the Squam Lakes is an important aspect of ensuring the watershed management plan’s success. Monitoring goals are established in the Action Plan in Section 5.2 1.5 Public Engagement and Community Involvement Kick-off Meeting On January 20, 2016, more than 50 individuals gathered to celebrate the Squam Lakes watershed and kick-off the update of the Squam Lakes Watershed Management Plan. After a brief presentation about the Squam Lakes watershed and the planning process, participants divided into small groups to discuss the following topics: ? ? ? How do we enhance the public’s understanding of the Squam watershed project and how do we encourage people to be involved? What are your thoughts about a new Squam Watershed Management Plan? What do we need to address? What do you think are the issues and priorities around the economy, environment, and culture of the Squam Lakes watershed? At the end of the meeting, the entire group came back together to summarize the breakout sessions. Speaker Series and Science Pub Events The SLA worked with local partners to host public programs that pertain to the watershed management planning process. Three programs were held: ? ? ? 3/27/2019: Speaker Series (landscape and design to protect water quality) 9/11/2019: Science Pub (climate change) 10/16/2019: Science Pub (land conservation, stream restoration) SQUAM LAKES ASSOCIATION 13 SQUAM LAKES | WATERSHED MANAGEMENT PLAN Meetings with Town Officials The Lakes Region Planning Commission (LRPC) was responsible for reaching out to town officials and board members (selectboards, planning boards, and conservation commissions) and including them in the watershed management planning process. On February 13, 2019, the LRPC introduced the results of the buildout analysis to town officials and the public. LRPC followed up on this meeting in September 2019 through November 2019 at meetings with the planning board for each watershed town: Ashland, Center Harbor, Holderness, Moultonborough, and Sandwich. SLA Annual Meetings The Squam Lakes Watershed Management Plan has been a major point of discussion at every SLA annual meeting since 2016. Weed Watcher Trainings The SLA trains individuals to be the first line of defense against new aquatic invasive species and new patches of variable milfoil (an aquatic invasive species already present in the Squam Lakes). Weed Watcher trainings were held every other Saturday between June and August 2018 and on three dates in 2019: 6/22, 7/20, and 8/23. Stakeholder Interviews During spring 2016, interviews were conducted with stakeholders to determine watershed users’ knowledge about watershed issues, identify key issues in the Squam Watershed, and engage stakeholders in the watershed management planning process. Qualitative analysis techniques were applied to determine key issues and themes which should be incorporated to the new Squam Lakes Watershed Management Plan. Interview highlights: ? ? ? ? ? ? ? Water quality is a primary concern. Tributaries and upland areas are important. Management should focus on the watershed as a whole. The use of the watershed is important, and the frequency and intensity of use are issues. The development of land for residential and business uses needs to be considered. It is important to improve the economic well-being and quality of life through job creation and growing income. All five towns in the watershed need to be involved. Need dialog between communities. Need to engage lots of people; the new plan should be everyone’s plan. Complete the plan in a timely manner and implement the new plan soon thereafter. The Watershed Management Plan will help with finding a balance for the use and development of the watershed. Survey of Recreational Visitors A survey of recreational visitors was conducted over two days in July 2016 at the West Rattlesnake trailhead, the Holderness boat launch, campsites, and the SLA headquarters in Holderness. The survey was designed to gather demographic and qualitative data about the visitors, their purpose for coming to the Squam Lakes Watershed, their opinion about water quality, and what they identify as threats to the watershed. A summary of the survey findings is presented below: ? ? ? ? ? 226 people participated in the survey that was evenly distributed over each day. 83% of respondents do not live in the Squam Lakes watershed, of which 23% had not visited the Squam region before, and 80% were staying one week or less. During their visit to the Squam Lakes watershed, 39% of all respondents planned to spend less than $100, and 29% planned to spend greater than $500. Hiking, swimming, and boating were the most popular activities that respondents engaged in. People come for the recreational opportunities, visiting family and friends, clean water, undeveloped landscape, and fewer people engaged in similar pursuits. SQUAM LAKES ASSOCIATION 14 SQUAM LAKES | WATERSHED MANAGEMENT PLAN ? ? 57% of respondents expressed that they are concerned, very concerned, or extremely concerned about water quality in the lakes. People cited development of land, roads, and climate change as the top three potential threats to the watershed. 1.6 Current and Historic Efforts in the Squam Watershed Lakes Lay Monitoring Program (1979-present): The SLA has been collecting water quality data from Squam Lakes since 1979, in partnership with the University of New Hampshire Cooperative Extension’s Lakes Lay Monitoring Program (LLMP). This volunteer program runs June through August and collects several parameters at thirteen sites across the Squam Lakes. In addition to the volunteer monitoring portion of this program, biologists from the LLMP visit the Squam Lakes once per month in June, July, and August. Parameters measured include water clarity, chlorophyll-a, total phosphorus, total color, alkalinity, pH, and dissolved oxygen. Septic System Survey Data for Shoreland Properties (1998-1999) In 1992-1993 and again in 1998-1999, the SLA conducted a septic system survey for shoreland properties around the lake. The earlier survey had a 66% response rate, and the later study collected data from 88% of shorefront properties. The two studies resulted in the following summary and conclusions: The initial and subsequent review of town files may have led to an incentive to improve record keeping because in almost all cases, record accuracy and completeness had improved significantly over the project period. The data were mapped based on two survey criteria deemed to be of primary significance: age of system and distance of subsurface sanitary, septic system, or other waste management system from lake. The graphical depiction of these criteria did not reveal any clear patterns in the potential failure risk of septic systems. The graphical representation of tax lots necessary for the mapping of the septic data did lead to an evaluation of the density of shoreland development. Tributary Monitoring study (1999-2001) In late 1998, the SLA and UNH LLMP developed a monitoring program to assess each of the subwatersheds in the Squam Lakes Watershed. The program was an intensive study of the major tributaries entering the Squam Lakes with the goal of determining the water budget and nutrient contributions of each of the subwatersheds. This tributary monitoring program was conducted from July 1999 through June 2000 and provided baseline hydrologic and phosphorus budgets for the Squam Lakes. Bioinventory (2001-2002) A biological inventory of the Squam Lakes Watershed was performed between July 2001 and July 2002. The purpose of the inventory was to establish representative monitoring plots and to collect baseline biological data from these locations. During the baseline bioinventory study, a total of 827 distinct species were identified and confirmed to be present in the Squam Lakes watershed. LoVoTECs (2012-2016) From 2012-2016, the SLA participated in a statewide stream monitoring program that measured stream depth, temperature, and specific conductance in streams throughout New Hampshire. One site was located at an unnamed brook running through Belknap Woods into Dog Cove, and the other sensors were deployed in Mill Brook. The sensors recorded measurements every 4-15 minutes from 2012-2016. The results from 2014 show Mill Brook falls within normal healthy limits. The water coming out of Belknap Woods fluctuates between the normal and low-impact categories. Results also show that the higher conductivity readings at Belknap Woods are likely related to impact from road salt. SQUAM LAKES ASSOCIATION 15 SQUAM LAKES | WATERSHED MANAGEMENT PLAN Watershed Reports (2012-present) In 2012, the SLA began publishing the Squam Watershed Report. This annual publication is a compilation of all the data collected in the Squam Lakes Watershed each year. While the reports vary from year to year, they generally include data and analysis about water quality, land protection, fisheries, invasive species (both aquatic and terrestrial), loons, and land conservation. Aquatic Invasive Species Variable milfoil is the primary aquatic invasive species in the Squam Lakes Watershed, and the SLA has been successfully managing it since 2000, resulting in a reduction in both the amount and spread of milfoil. The Chinese mystery snail, an invasive aquatic invertebrate animal, is also present in the Squam Lakes. Control of both variable milfoil and the Chinese mystery snail and prevention of the introduction of other aquatic invasives is a focus of the Squam Lakes Watershed Management Plan. Investigation of Contaminants in the Squam Lakes Watershed (2018-2019) In 2018, the SLA received funding to investigate various contaminants identified in the Squam Lakes Watershed. The SLA began working with Geosyntec, an environmental consulting firm, to create a preliminary plan to widen the geographic scope of contaminant sampling in the Squam Lakes Watershed. The short-term sampling effort will inform a longer-term investigation. Staff at the SLA conducted sediment sampling in seven Squam Lakes tributaries in early November 2018. Sediment samples were tested for DDT (dichlorodiphenyltrichloroethane), PCBs (polychlorinated biphenyls), and dioxins/furans. These chemicals are persistent and ubiquitous in the environment, meaning they are very slow to break down in nature and can be found in all environments due to high levels of wide-spread historic use. Generally, the contaminants of concern - DDT, dioxins/furans, and PCBs - tend to stick to sediment, which is why the SLA have tested tributary sediment and not water samples. These contaminants are insoluble in water and therefore less of a hazard to swimmers. Concentrations of these contaminants were compared to EPA Regional Screening Levels for recreational exposure to sediment (i.e., swimming, wading, etc.). Results indicated that concentrations of these compounds in sediment do not pose a risk to human health through recreational exposure. As these compounds do accumulate in fish, the exposure to humans is primarily through fish consumption. Levels of these contaminants are known to accumulate up the food chain and can impact both aquatic invertebrates and vertebrates, including apex predators such as loons (the Loon Preservation Committee has also performed sediment analysis and continues to test loon eggs for DDT and PCBs, and other contaminants). Further study is recommended. Sediment mitigation projects, such as those recommended in this plan to reduce nutrient loading, are also beneficial to reduce potential legacy contaminants from entering the Squam Lakes. SQUAM LAKES ASSOCIATION 16 SQUAM LAKES | WATERSHED MANAGEMENT PLAN 2. The Squam Lakes Watershed 2.1 Watershed description The Squam Lakes Watershed, located in central New Hampshire, covers 36,644 acres. At the heart of the watershed is Squam Lake (6,762 acres) and Little Squam Lake (408 acres). The watershed is 20% open water with 85% of the surrounding watershed landscape as forest. There is minimal development in the Squam Lakes Watershed; less than 3% of the watershed is considered low density development, while high and medium density development are less than 0.1% of the total watershed area. There are 34 tributaries contributing flows to the Squam River and Squam Lakes. Water flows generally from east to west from Squam Lake through the Squam Channel into Little Squam Lake and through two miles of the Squam River until the lake impoundment in Ashland. Ultimately, the Squam River drains into the Pemigewasset River in Ashland. The watershed is divided among multiple political boundaries: three counties (Belknap, Carroll, and Grafton) and seven towns (Ashland, Campton, Center Harbor, Holderness, Meredith, Moultonborough, and Sandwich). Elevations range from 2,212 feet on Mount Percival in the Squam Range, which forms the northern boundary of the watershed, to 561 feet at the outlet dam in Ashland. Twenty-six percent (26%) of the Squam Lakes Watershed is permanently protected through conservation easements. Figure 2-1: Map of the Squam Lake and Little Squam Lake Watersheds and their sub-basins. Cross-hatched areas are direct shoreline input. Red dots indicate water quality monitoring sites. LS West (in Little Squam Lake) and Deephaven (in Squam Lake) are the deepest points in each lake. SQUAM LAKES ASSOCIATION 17 SQUAM LAKES | WATERSHED MANAGEMENT PLAN 2.2 Physical Characteristics 2.2.1 Surficial Geology Surficial earth materials include unconsolidated sediments (sand, gravel, etc.) of glacial and nonglacial origin. Most of these deposits formed during and after the latest episode of glaciation within the last 25,000 years. Surficial sediments cover bedrock over much of the watershed. Till is the most widespread surficial deposit in the Squam Lakes watershed. It blankets the hills and sides of mountains, although parts of it have been disturbed by mass movements and surface water runoff on the steeper slopes. There are many shallow areas and islands on Squam Lake where large boulders are present. These boulders resulted from extensive capture and movement of the Winnipesaukee Tonalite bedrock as glacial ice flowed over the area. Glacial sand and gravel were emplaced in the Squam Lakes watershed, most commonly in lowland areas by waters flowing out of melting ice during recession of the Laurentide Ice Sheet. Ice-contact deposits formed where water laid glacial sediments upon or beside melting ice in the marginal zone of the retreating ice sheet. The resulting sand and gravel deposits may show hummock topography, including locally steep slopes where the ice once stood and depressions (kettles) left by melting of stray buried ice blocks. Ice-contact sand and gravel deposits occur in the upper Owl Brook valley in Holderness (Thompson, 2015). Outwash consists of sand and gravel laid down by glacial meltwater streams on valley bottoms as the ice sheet retreated from the study area. Small outwash deposits occur on the northwest side of Squam Lake and along Owl Brook in Holderness (Thompson, 2015). Terraces of sand and gravel are scattered along the shorelines of Squam Lake and Little Squam Lake in Holderness and Ashland. These deposits were formed when both lakes were slightly higher than today, and the lake surfaces probably stood at an elevation of about 580 ft. The higher lake system may have been dammed by a temporary plug of glacial till in a narrow part of the Squam River valley, just upstream from the modern dam that now regulates the lake levels. Sand and gravel in the lower Owl Brook valley are thought to be glacial outwash that the brook carried into ancestral Little Squam Lake. Stream terraces are remnants of past floodplains that have been left as streams eroded down to their modern levels. These flat-topped deposits consist mostly of sand and gravel that were reworked from older glacial sediments. They occur along parts of Owl Brook in Holderness (Thompson, 2015). Fine-grained and organic-rich sediments of postglacial age have been deposited in low, flat, poorly drained areas. This unit occurs in upland areas and in some poorly drained valley environments associated with flood plains. Alluvial sand, gravel, silt, and organic material have been deposited by late glacial to modern streams. Sediment coarseness varies depending on the depositional environment, but in general there is a higher percentage of coarse gravel along steep streams in mountainous areas around the periphery of the watershed, while siltysandy sediments are associated with more sluggish streams in gently sloping valley bottoms. 2.2.2 Soil Erosion Potential Soil type and soil erosion potential are important considerations when planning for development. Soils with lower infiltration rates and higher runoff potential can contribute greater amounts of nonpoint source pollution (nutrients, sediments, bacteria, etc.) to surface water. Soil erosion potential is determined from the soil hydrologic group, where soils are ranked from A-D, with A as the highest soil erosion potential and D as the lowest. Most soils in the Squam Lakes Watershed are ranked as B (24%) with moderately low runoff potential and C (57%) with moderately high runoff potential. SQUAM LAKES ASSOCIATION 18 SQUAM LAKES | WATERSHED MANAGEMENT PLAN 2.3 Population According to the United States Census Bureau, most towns in the Squam Lakes watershed have experienced steady population growth over the last 30 years. The populations of watershed towns combined have grown from 7,312 people in 1980 to 10,650 people in 2010 – a 46% increase. During that same time span, housing units in the target communities grew from 5,952 to 9,657 – a 62% increase. In most cases the rate of housing growth has been higher than the population growth rate. Note that the population and housing data account for each entire town, not just that town’s population and housing within the watershed. A more extensive breakdown of population in watershed towns was included in the Squam Lakes Watershed Build-Out Analysis (Lakes Region Planning Commission, 2018). 2.4 Land Cover Land cover in a watershed helps identify areas that contribute nonpoint source pollution, such as phosphorus, to surface waters. For example, residential and urbanized areas contribute more nutrients to surface waters than undeveloped forest lands. Details on the land cover assessment are provided in Section 3.2. Today, in the Squam Lake Watershed, development accounts for 6% (476 acres), while forested areas dominate at 81% (7002 acres). Wetlands and open water represent 8% (696 acres) of the watershed, not including Squam Lake. Agriculture represents 4% (306 acres) and includes hayfields, and grazing pastures. In the Little Squam Lake Watershed, development accounts for 7% (258 acres), while forested areas cover at 84% (2890 acres). Wetlands and open water represent 2% (93 acres) of the watershed, not including Little Squam Lake. Agriculture represents 4% (142 acres) of the land cover. Developed areas within the Squam Lakes watershed are characterized by impervious surfaces, including areas with asphalt, concrete, and rooftops that force rain and snow that would otherwise soak into the ground to runoff as stormwater. Stormwater runoff carries pollutants to waterbodies that may be harmful to aquatic life, including sediments, nutrients, pathogens, pesticides, hydrocarbons, and metals. The build-out analysis conducted for the watershed, coupled with projected population growth trends, indicates that the percentage of developed area will continue to increase. Therefore, it is imperative that watershed communities incorporate low impact development (LID) techniques into new development projects. More information on BMP implementation can be found in the Action Plan in Section 5.2. 2.5 Lake Morphology and Morphometry The morphology (shape) and bathymetry (depth) of lakes are considered reliable predictors of water clarity and lake ecology. Large, deep lakes are typically clearer than small, shallow lakes as the differences in lake area, number and volume of upstream lakes, and flushing rate affect lake function and health. The surface area of Squam Lake (6,762 acres) and Little Squam Lake (408 acres) is characterized by complex morphology with numerous coves and bays that generate an extensive shoreline length and distinct basins that may limit water and nutrient movement at certain times of the year. Squam Lake has a mean depth of 7 m, a maximum depth of 27 m, and a volume of 187,047,000 m3. Squam Lake’s areal water load is 2.8 m/yr, and its flushing rate is 0.4 times per year. The low areal water load and flushing rate means that the entire volume of the Squam Lakes is replaced every 2.4 years, which increases time for pollutants to settle in lake bottom sediments or be taken up by biota. Little Squam Lake has a mean depth of 10 m, a maximum depth of 21 m, and a volume of 17,431,112 m3. Little Squam Lake’s areal water load is 59.5 m/yr, and its flushing rate is 5.8 times per year. The moderatelyhigh areal water load and flushing rate means that the entire volume of Little Squam Lake is replaced multiple times every year, which decreases time for pollutants to settle in lake bottom sediments or be taken up by biota. The statistics presented here were derived from (or cited in) LLRM documentation (see Section 3.2). SQUAM LAKES ASSOCIATION 19 SQUAM LAKES | WATERSHED MANAGEMENT PLAN 3. Water Quality Assessment 3.1 Water Quality and Assimilative Capacity Analysis 3.1.1 Analysis Design and Methods Data acquisition and analysis followed the protocol established in the April 18, 2018 Site Specific Project Plan (SSPP). As established in the SSPP, the parameters assessed for the Squam Lakes Watershed Management Plan included Secchi disk transparency (SDT), as well as chlorophyll-a and total phosphorus from epilimnetic composite samples from the summer season (May 24th through September 15th). Water quality data were accessed from the NHDES Environmental Monitoring Database (EMD). EMD data were available from 19792017. Using these data, we ran summary statistics and trend analyses on historic data (1979-2007), recent data (2008-2017), and all data (1979-2017). Trends in water quality for each parameter were analyzed by the MannKendall test (rkt, R statistical program; Marchetto, 2015). 3.1.2 Water Quality Criteria According to the NH Consolidated Assessment and Listing Methodology (CALM), New Hampshire’s water quality criteria set the baseline quality that all surface waters of the state must meet in order to protect their designated uses and are the measure for identifying where water quality violations exist and for determining the effectiveness of regulatory pollution control and prevention programs. Designated uses are the desirable activities and services that surface waters should be able to support, and include uses for aquatic life, fish consumption, shellfish consumption, drinking water supply, primary contact recreation (swimming), secondary contact recreation (boating and fishing), and wildlife. Water quality criteria may be found in RSA 485-A:8, I-V and in the state’s surface water quality regulations Env-Wq 1700. For lakes, water quality criteria vary depending on the lake’s trophic status, since each trophic state has a certain algal biomass (chlorophyll-a) that represents a balanced, integrated, and adaptive community (Table 3-1). To determine if a waterbody is meeting its designated uses, water quality criteria for various water quality parameters (e.g., chlorophyll-a, total phosphorus, dissolved oxygen, pH, and toxics) are applied to the water quality data. If a waterbody meets or is better than the water quality criteria, the designated use is supported. If the waterbody does not meet or is worse than the water quality criteria, it is considered impaired for the designated use. Aquatic Life Use (ALU) and Primary Contact Recreation (PCR) are the two major uses for New Hampshire lakes, with ALU being the focus of watershed management plans. For ALU assessment, phosphorus and chlorophyll-a are combined per the decision matrix presented in Table 3-2. The chlorophyll-a concentration will dictate the assessment if both chlorophyll-a and phosphorus data are available and the assessments differ. Dissolved oxygen is also used as an indicator for ALU assessment and is critical to the balanced, integrative, and adaptive community of organisms (see Env-Wq 1703.19). For Class A waters, non-support use determinations are based on a daily average measurement of 75% dissolved oxygen saturation or less and an instantaneous dissolved oxygen measurement of 6 ppm or less, which apply to any depth in a vertical profile (except within 1 meter of lake bottom) collected from June 1 to September 30 (see Env-Wq 1703.07). Table 3-1: Trophic state water quality criteria in New Hampshire. Trophic State Oligotrophic Mesotrophic Eutrophic Total Phosphorus (ppb) 12.0-28.0 SQUAM LAKES ASSOCIATION Chlorophyll-a (ppb) 5.0-11.0 20 SQUAM LAKES | WATERSHED MANAGEMENT PLAN Table 3-2. Decision matrix for aquatic life use (ALU) assessment in New Hampshire. TP = total phosphorus. Chl-a = chlorophyll-a, a surrogate measure for algae concentration. Nutrient Assessments TP Threshold Exceeded Chl-a Threshold Exceeded Chl-a Threshold NOT Exceeded Insufficient Info for Chl-a Impaired Potential Non-support Insufficient Info TP Threshold NOT Exceeded Impaired Fully Supporting Insufficient Info Insufficient Info for TP Impaired Fully Supporting Insufficient Info 3.1.3 Squam Lake Water Quality Total Phosphorus, Chlorophyll-a, Secchi Disk Transparency Water quality in Squam Lake is stable and meets water quality criteria for oligotrophic lakes. Table 3-3 shows the summary data for Squam Lake’s deep spot near Deephaven Reef. Epilimnetic total phosphorus exhibits no annual trends since 1982, when TP data was first collected (Figure 3-1). The historic (1982-2007) record showed a trend toward increasing (worsening) chlorophyll-a that leveled off after 2008 (Figure 3-2). For water clarity measured by Secchi disk, the entire data set and the most recent ten years of data show a trend toward increasing water clarity, indicating a possible improvement in water clarity (Figure 3-3). Table 3-3: Squam Lake summary statistics for epilimnetic total phosphorus, epilimnetic chlorophyll-a, and Secchi disk transparency during the summer season (May 24-September 15). Trends were determined using the Mann-Kendall trend analysis test. Squam Lake Total Phosphorus All years (1982-2017, y=31) Historic (1982-2007, y=21) Recent (2008-2017, y=10) Squam Lake Chlorophyll-a All years (1982-2017, y=36) Historic (1982-2007, y=26) Recent (2008-2017, y=10) Squam Lake Secchi Disk Transparency All years (1982-2017, y=34) Historic (1982-2007, y=24) Recent (2008-2017, y=10) SQUAM LAKES ASSOCIATION n 87 51 36 n 93 58 35 n 92 55 37 Mean (ppb) 6.2 6.1 6.4 Mean (ppb) 2 2 1.9 Mean (m) 8.7 8.5 9 Median (ppb) 6 5.6 6.5 Median (ppb) 1.9 1.9 1.7 Median (m) 8.8 8.6 9.2 Min (ppb) 1.5 1.5 3.4 Min (ppb) 0.5 0.5 1.1 Min (m) 6.3 6.5 6.3 Max (ppb) 6.2 18.3 13.3 Max (ppb) 6 6 3.4 Max (m) 11.4 11.4 11.4 Trend no trend no trend no trend Trend no trend declining no trend Trend improving no trend improving MK pvalue 0.683 1 0.788 MK pvalue 0.185 0.015 0.857 MK pvalue 0.048 0.766 0.025 MK slope 0.021 -0.008 -0.02 MK slope 0.015 0.05 -0.008 MK slope 0.03 0.009 0.225 21 SQUAM LAKES | WATERSHED MANAGEMENT PLAN Figure 3-1: Annual median epilimnetic total phosphorus for the deep spot of Squam Lake, 1982-2017. Gaps reflect years with no data. Figure 3-2: Annual median epilimnetic chlorophyll-a for the deep spot of Squam Lake, 1982-2017 Figure 3-3: Annual average Secchi disk transparency for the deep spot of Squam Lake, 1982-2017. Gaps reflect years with no data. SQUAM LAKES ASSOCIATION 22 SQUAM LAKES | WATERSHED MANAGEMENT PLAN 3.1.4 Little Squam Lake Water Quality Total Phosphorus, Chlorophyll-a, Secchi Disk Transparency Water quality in Little Squam Lake is stable and meets water quality criteria for oligotrophic lakes. Table 3-4 shows the summary data for Little Squam Lake’s deep spot at the western edge of the lake. Epilimnetic total phosphorus exhibits no annual trends since 1980, when TP data was first collected (Figure 3-4). The historic (1979-2007) record showed no trend in chlorophyll-a concentrations (Figure 3-5). For water clarity measured by Secchi disk, the entire data set and the most recent ten years of data also show no trend (Figure 3-6). Table 3-4: Little Squam Lake summary statistics for epilimnetic total phosphorus, epilimnetic chlorophyll-a, and Secchi disk transparency during the summer season (May 24-September 15). Trends were determined using the Mann-Kendall trend analysis test. Little Squam Lake Total Phosphorus All years (1980-2017, y=33) Historic (1980-2007, y=23) Recent (2008-2017, y=10) Little Squam Lake Chlorophyll-a All years (1979-2017, y=39) Historic (1979-2007, y=29) Recent (2008-2017, y=10) Little Squam Lake Secchi Disk Transparency All years (1979-2017, y=39) Historic (1979-2007, y=29) Recent (2008-2017, y=10) n 191 101 90 n 463 362 101 n 571 406 165 Mean (ppb) 7 7.3 6.5 Mean (ppb) 1.9 1.9 1.9 Mean (m) 7.3 7.1 7.3 Median (ppb) 6.4 6.3 6.4 Median (ppb) 1.9 2 1.8 Median (m) 7.3 7.3 7.4 Min (ppb) 1.5 1.5 4.2 Min (ppb) 0.4 0.4 1 Min (m) 5 5 5.9 Max (ppb) 29.4 29.4 9.8 Max (ppb) 4.3 4.3 3 Max (m) 9.6 9.6 8.9 Trend no trend no trend no trend Trend no trend no trend no trend Mean (m) no trend no trend no trend MK pvalue 0.336 0.161 0.474 MK pvalue 0.37 0.053 0.474 Median (m) 0.468 0.75 0.589 MK slope -0.021 -0.056 0.181 MK slope 0.008 0.03 0.054 Min (m) -0.006 0.01 0.075 Figure 3-4: Annual median epilimnetic total phosphorus for the deep spot of Little Squam Lake, 1980-2017. Gaps reflect years with no data. SQUAM LAKES ASSOCIATION 23 SQUAM LAKES | WATERSHED MANAGEMENT PLAN Figure 3-5: Annual median epilimnetic chlorophyll-a for the deep spot of Little Squam Lake, 1979-2017. Figure 3-6: Annual average Secchi disk transparency for the deep spot of Little Squam Lake, 1979-2017. 3.1.5 Assimilative Capacity The assimilative capacity of a waterbody describes the amount of pollutant that can be added to that waterbody without exceeding water quality criteria. For New Hampshire lakes, the water quality criteria for phosphorus and chlorophyll-a are based on the lake’s trophic status. The NHDES has determined that the trophic status of Squam Lakes is categorized as oligotrophic. For oligotrophic lakes, the water quality criteria for phosphorus and chlorophyll-a is 8.0 ppb and 3.3 ppb, respectively. Total assimilative capacity is the difference between zero and the water quality criteria and thus is set by the water quality criteria. The NH Surface Water Quality Standards (ENV-Wq-1708) require that 10% of the assimilative capacity for a waterbody must be held in reserve. For Squam Lake and Little Squam Lake, the reserve assimilative capacity for total phosphorus and chlorophyll-a is 7.2 ppb and 3.0 ppb, respectively. The remaining assimilative capacity is the calculated difference between the water quality criteria and the existing median water quality value. Epilimnetic total phosphorus and chlorophylla levels should remain below 7.2 ppb and 3.0 ppb, respectively, to be in the Tier 2 High Quality Water category for an oligotrophic lake. Tier 2 waters in New Hampshire are of the highest quality—water quality is better than 10% of the criteria (Table 3-5). Tier 1 waters are within 10% of the water quality criteria, and impaired waters exhibit water quality that exceeds the state criteria. SQUAM LAKES ASSOCIATION 24 SQUAM LAKES | WATERSHED MANAGEMENT PLAN Table 3-5: NH surface water classification assessment criteria. Water Quality Classification Tier 2 Tier 1 Impaired Description Water quality is better than 10% of the water quality criteria Water quality is within 10% of the water quality criteria Water quality exceeds the criteria Total Phosphorus (ppb) Chlorophyll-a (ppb) 5.0 Recent (2008-2017) median epilimnetic total phosphorus and chlorophyll-a for the deepest spots of both Squam Lakes were used to calculate the total, reserve, and remaining assimilative capacity. For Squam Lake and Little Squam Lake, the existing median for both total phosphorus and chlorophyll-a is better than the reserve assimilative capacity threshold and thus meet the classification of Tier 2 for high quality waters ( Table 3-6). Table 3-6: Assimilative capacity, reserve assimilative capacity, remaining assimilative capacity, and waterbody classification for total phosphorus and chlorophyll-a in Squam Lake and Little Squam Lake. Squam Lake Assimilative Capacity Existing Median TP (ppb) Assimilative Capacity (ppb) Total Phosphorus Chlorophyll-a 6.5 1.7 8.0 3.3 Little Squam Lake Assimilative Capacity Existing Median TP (ppb) Assimilative Capacity (ppb) Total Phosphorus Chlorophyll-a 6.4 1.8 8.0 3.3 Reserve Assimilative Capacity (ppb) 7.2 3.0 Reserve Assimilative Capacity (ppb) 7.2 3.0 Remaining assimilative capacity (ppb) 0.7 1.3 Remaining assimilative capacity (ppb) 0.8 1.2 Waterbody classification Tier 2 Tier 2 Waterbody classification Tier 2 Tier 2 3.1.6 Dissolved Oxygen and Hypolimnion Total Phosphorus Dissolved oxygen concentrations from the most recent ten years were also examined to understand the depth at which each lake experiences anoxia and how many days anoxia occurs. These data were used to calculate internal loading in the watershed model. Also, for the internal load calculation, the difference between epilimnetic and hypolimnetic total phosphorus levels was calculated. For Squam Lake, the difference in TP levels was calculated at the Lake’s deepest point, Deephaven Reef. Multiple sites were used to calculate the anoxic zone of the lake since there are so many distinct deep basins that experience anoxia (Table 3-7). When the dissolved oxygen concentration is less than 1.0 mg/L, the conditions are considered anoxia and oxygen deprived. SQUAM LAKES ASSOCIATION 25 SQUAM LAKES | WATERSHED MANAGEMENT PLAN Table 3-7: Date and depth of anoxic conditions in Squam Lake water quality testing sites. SITE 5 Livermore Cove 10 Sandwich Bay 10 Sandwich Bay 10 Sandwich Bay 12 Moultonboro Bay 14 Sturtevant Bay 14 Sturtevant Bay 14 Sturtevant Bay 14 Sturtevant Bay 14 Sturtevant Bay 14 Sturtevant Bay 14 Sturtevant Bay 14 Sturtevant Bay 14 Sturtevant Bay 16 Dog Cove 16 Dog Cove 18 Piper Cove 18 Piper Cove 18 Piper Cove 18 Piper Cove 18 Piper Cove 18 Piper Cove 18 Piper Cove Deep Haven Loon Reef Loon Reef DATE 8/18/2010 8/18/2016 8/15/2017 8/16/2018 9/28/2016 7/20/2011 8/12/2014 7/16/2015 8/12/2015 7/12/2016 9/28/2016 7/12/2017 8/15/2017 8/16/2018 7/20/2011 8/20/2013 9/24/2010 7/20/2011 8/20/2013 8/18/2016 7/12/2017 8/15/2017 8/16/2018 8/15/2017 8/18/2016 8/15/2017 DEPTH (m) 8 21 19.958 20.693 13.5 13 15 16.5 13.5 16 12 17 12.5 13.5 12 9 13.5 13 10.5 11.5 13.98 11.183 11.436 29.398 23 24.028 TEMP (C) 22.2 6.5 6.923 6.482 15.6 9.5 9.7 8.5 10.1 11.1 16.7 9.8 12.2 9.6 16.4 21.3 17.9 12.9 17.5 17.5 13.667 15.99 14.012 7.727 10.6 9.806 DO (mg/L) 0 0.47 0.99 0.98 0.15 0.47 0.98 0.66 0.94 0.89 0.17 0.94 0.68 0.26 0.02 0.08 0 0.59 0.85 0.52 0.92 0.93 0.91 0.97 0.93 0.98 Station Max Depth (m) 9.1 22.9 22.9 22.9 18.6 18 18 18 18 18 18 18 18 18 18.2 18.2 12.2 12.2 12.2 12.2 12.2 12.2 12.2 30 27.7 27.7 For Little Squam Lake, only one site was used when looking at anoxic conditions to calculate internal loading and there were only three days where anoxia was measured in the recent data (Table 3-8). Table 3-8: Date and depth of anoxic conditions in Little Squam Lake water quality testing sites. SITE Little Squam West Little Squam West Little Squam West DATE 9/24/2010 8/15/2017 8/16/2018 DEPTH (m) 16.0 19.329 18.865 TEMP (C) 8.2 6.946 5.605 DO (mg/L) 0.65 0.97 0.98 Station Max Depth (m) 21.9 21.9 21.9 3.1.7 Cyanobacteria Cyanobacteria are actually a group of bacteria that are closely related to algae; however, they are not considered algae. They are the only group of bacteria that photosynthesize, or use light and carbon dioxide to create their own food the same way that plants do. Different types of cyanobacteria may be green, blue, red, or brown, but the one thing they have in common is their tendency to float on the surface in a layer that is often described as “oily” or “scummy” looking. SQUAM LAKES ASSOCIATION 26 SQUAM LAKES | WATERSHED MANAGEMENT PLAN A “bloom” is a generic term used for rapidly reproducing colonies of bacteria or algae in bodies of water. These blooms tend to occur in bodies of water that have received a high input of nutrients, either by being disturbed from a sediment bed where it previously laid dormant, or from some external input of nutrients, such as from fertilizer runoff. In September 2017, a sample from Squam contained at least two types of the bacteria Anabaena and Aphanocapsa. It was a small, isolated event that did not cause any known incidents or issues for those on the lake. In October 2018, a cyanobacteria bloom was reported on White Oak Pond. The bloom cleared within several days. 3.2 Buildout analysis The build-out analysis for the Squam Lakes Watershed area provides estimates about the potential for new development, including the amount of land area in the watershed that could be developed and the number of new buildings, based on current zoning standards. The build-out also presents information about where the development has the potential to occur. The build-out analysis provides a full build-out scenario based on current zoning standards, and should be viewed as an estimate only. It is a planning tool that communities can utilize for guiding future land use activities in the watershed as well as for exploring conservation actions. The greatest amount of existing development is concentrated around the western and southern shores of Squam Lake and around the shores of Little Squam Lake. Large portions of the watershed are in permanent conservation. Nearly 13,000 acres of land in the study area (46%) are constrained in some manner. The build-out analysis shows that there is room for potential development in each of the five communities, the amount depends upon the land available in the community and the applicable restrictions. For the entire study area the analysis estimates that 5,175 new buildings could be added in the watershed. Projections as to when build-out levels are reached can vary based on several factors, some of which are subject to decisions made by landowners and towns, including the amount of land available for development, the local zoning regulations, and the rate at which development occurs. The projected time frame for full build-out for the entire watershed is 2148. The full buildout analysis, including all maps and figures, is available on the SLA website (squamlakes.org). 3.3 Watershed Modeling The LLRM is a spreadsheet-based tool that estimates the water and phosphorus loading budget for the lakes and their tributaries. Water and phosphorus loads (in the form of mass and concentration) are traced from various sources in the watershed, through tributary basins, and into the lake. The model incorporates data about land cover, watershed boundaries, point sources, septic systems, waterfowl, rainfall, and internal phosphorus loading, combined with many coefficients and equations from scientific literature on lakes and nutrient cycling. The outcome of this model can be used to identify current and future pollution sources, estimate pollution limits and water quality goals, and guide watershed improvement projects. Squam and Little Squam lakes were modeled separately. 3.3.1 Watershed and Sub-basin Delineation Both Squam and Little Squam lake watersheds were broken out into sub-basins. The U.S. Geological Society StreamStats was used to delineate 17 sub-basins in the Squam Lake Watershed and 7 in the Little Squam Lake Watershed. All other land areas were considered direct shoreline input to the lakes. SQUAM LAKES ASSOCIATION 27 SQUAM LAKES | WATERSHED MANAGEMENT PLAN 3.3.2 Land Cover Update Land cover is the primary input to the LLRM since it determines the quantity and quality of water that flows into the Squam Lakes. The LLRM uses water and phosphorus loading coefficients for different land cover types to estimate how much water and phosphorus reaches the Squam Lakes. Providing an adequate representation of current land cover contributes to a more accurate model. The 2001 New Hampshire Land Cover Assessment (NHLCA) from NH GRANIT was used as a starting point for determining current land cover in the Squam Lakes Watershed. Land cover types from the NHLCA from 2001 were translated to the land cover types used by the LLRM. Using Google Earth satellite images from 6/2/2018, as well as local knowledge and ground-truthing in the field, major land cover changes were noted and changed within the working land cover file. The following assumptions were made during the land cover correction process: ? ? ? ? ? Forest 3: Mixed was the default category for any land determined to be forest. Athletic fields and cemeteries were labeled as Urban 5: Open Space. Residential lawns were labeled as Urban 1: Low Density Residential. Unpaved roads from the NHDOT roads layer from NH GRANIT were labeled as Other 2: Unpaved Roads. Wetlands from the National Wetlands Inventory were labeled as Forest 4: Wetlands. Final land cover data is shown in Figure 3-7. Figure 3-7: Land cover in the Squam Lakes Watershed after correcting existing land cover files. SQUAM LAKES ASSOCIATION 28 SQUAM LAKES | WATERSHED MANAGEMENT PLAN 3.3.3 Other LLRM Inputs ? ? ? ? ? ? ? Precipitation: Monthly precipitation data were obtained from NOAA NCEI for the MEREDITH 2.9 SSW, NH US (Station ID: US1NHBK0009) weather station with 2008-9 data gaps not included in the 10-year average. Average annual precipitation totals from 2010-2017 were input to the model (49.4 in or 1.25 m). Septic system data was an estimate based on a number of sources including 2010 Census information for the state of New Hampshire, buildout analysis results from the Lakes Region Planning Commission, QGIS area calculations, Patricia Tarpey’s 2013 Plymouth State University master’s thesis, and Lake Waukewan (Meredith and Center Harbor, NH) and Winona (Center Harbor, NH) septic survey results. (A septic system survey was completed for lakeshore residents around Lake Waukewan and Lake Winona in 2014 as part of development of a watershed management plan. It was assumed that the relative break-out of seasonal or year-round and old or new systems would be similar to other lake watersheds in the area.) Assumed 133 waterfowl (0.3 per hectare of lake area) were contributing to the phosphorus loading for half the year. Lake area was calculated based on a clip from the NH GRANIT NHD Waterbody shapefile. Bathymetry data was based on extensive lake depth data gathered by Brad Washburn (1962). The Squam Lake bathymetry data produced a lake volume that was 20% greater than the NHDES 1989 trophic survey for Squam Lake, and 7% greater than the 2009 NHDES trophic survey for Little Squam Lake. Trophic survey volume estimates were used. Water quality data were obtained from the NHDES Environmental Monitoring Database. Both the Squam Lake and Little Squam Lake models were calibrated using data from each lake’s deepest point between 2008 and 2017. Data collection is summarized in the Water Quality and Assimilative Capacity Analysis Report. The most recent tributary water quality data was collected in 1999-2000. These data were used general guides but were not used to calibrate the model. Lake water quality data was also used to determine and calculate internal loading. Anoxia calculations to determine internal loading included dissolved oxygen data from other water quality sites for Squam Lake (Livermore Cove, Sandwich Bay, Moultonborough Bay, Sturtevant Bay, Dog Cove, Piper Cove, and Loon Reef). Atmospheric phosphorus deposits were incorporated primarily as dry deposition calculations—dust that gets blown up into the air and settles down somewhere else contains phosphorus. As development increases, so will atmospheric phosphorus. The atmospheric phosphorus export was set at 0.11 kg/ha/year, a value determined from existing scientific literature. 3.3.4 Model limitations There were several limitations to the model; literature values and best professional judgement were used in place of measured data, wherever appropriate. Acknowledging and understanding these model limitations is critical to interpreting model results and applying any derived conclusions to management decisions. The model should be viewed as one of many tools available for lake management. The model results should be updated regularly as new information is collected. Because the LLRM incorporates specific waterbody information and is flexible in applying new data inputs, it is a powerful tool that predicts in-lake total phosphorus concentrations with a high degree of confidence; however, model confidence can be increased with more data. The following lists specific limitations to the model: ? ? ? Minimal water quality data were available for tributaries. Septic information was based on regional estimates. Waterfowl estimates were based on default assumptions. SQUAM LAKES ASSOCIATION 29 SQUAM LAKES | WATERSHED MANAGEMENT PLAN ? ? Due to its morphometric complexity, Squam Lake would greatly benefit from a more advanced modeling approach, such as the BATHTUB model that could allow for hydrologic segmentation of distinct basins. Minimal water quality data were available for internal load estimates in all distinct basins and thus internal load may be underestimated for Squam Lake. 3.3.5 Calculating Pre-Development Phosphorus Loads To estimate phosphorus loading to the Squam Lakes before development occurred, all human development related land cover categories—including all urban, agriculture, excavation, timber harvesting, and unpaved roads—were changed to forest land cover. The estimate for pre-development loading was calculated without breaking each watershed into sub-basins. Other assumptions and changes for calculating pre-development phosphorus loads: ? ? ? ? Removed septic input. Removed internal loading input. Reduced atmospheric loading coefficient to 0.07 kg/ha/year. All other parameters were kept the same to the original model. 3.3.6 Calculating Future Phosphorus Loads The Squam Lakes Watershed build-out analysis from the LRPC was used to generate an estimate of changes in land cover at full build-out by 2148. We assumed that for every new building added to the watershed, some amount of developed land (residential, commercial, roads, etc.) will increase. To determine the amount and type of developed land added per new building, we used the number of existing buildings in the watershed to calculate how much of each developed land cover category is associated with each existing building in the watershed. These factors for developed land cover categories were multiplied by the number of new buildings possible and added to the current water and phosphorus load in the model. It was assumed that the new developed land at build-out will occur on current forest and agricultural land, so the area of developed land was subtracted proportionally from current forest and agricultural land. Other assumptions and changes for calculating future phosphorus loads: ? ? ? ? ? Did not change the precipitation input, even though precipitation will likely change in the future. Septic input was estimated using building numbers at full build-out using same proportion of seasonal and occupied homes. Internal loading was estimated to be the same proportion of the total phosphorus load at full build-out as it is currently. Increased atmospheric loading coefficient to 0.25 kg/ha/year. All other parameters were kept the same to the original model. 3.3.7 Results (Current, Pre-Development, and Future Load Estimates) Squam Lake Watershed In Squam Lake, the Dog Cove 1 sub-basin contributes the greatest annual phosphorus load followed by the direct shoreline area (Table 3-9). At full build-out, the amount of phosphorus entering Squam Lake will more than double (from 1,121 kg/ha/year to 2,805 kg/ha/year; Table 3-10). In Squam Lake, phosphorus load from the watershed (runoff and baseflow) contributes the greatest amount of phosphorus to the lake (Table 3-10, Figure 3-9). Septic input is estimated at 15% and internal loading is 1%. Septic and internal loading are rough estimates and will need further study to refine. At full build-out, the LLRM estimated that there will be an increase in relative impact from septic systems. This is based on a series of assumptions and should be refined to understand further, possibly by estimating building locations and limiting septic influence on the lake from only buildings within 250 feet from surface waters. SQUAM LAKES ASSOCIATION 30 SQUAM LAKES | WATERSHED MANAGEMENT PLAN Predicted in-lake phosphorus concentrations for Squam Lake were 7.9 ppb, compared to measured values for the lake’s deepest spot (Deephaven site) at 7.8 ppb (Table 3-11). Table 3-11 also includes mean total phosphorus concentrations for other lake sites for comparison. Measured values were increased by 20% as an estimate for year-round total phosphorus concentrations. There is limited year-round data for the Squam Lakes. Generally, total phosphorus concentrations are higher when the lake is not stratified. The Squam Lakes Association is currently conducting water quality monitoring during all months of the year, though only two seasons of data have been collected. Soon, the actual difference between phosphorus concentrations in the summer season and other seasons can be calculated. At full build-out, the LLRM predicts in-lake total phosphorus concentration will be 16.9 ppb, which would classify Squam Lake as eutrophic. Figure 3-8: Land cover summary for the Squam Lake and Little Squam Lake. Table 3-9: Summary of land area, water flow, and total phosphorus (TP) loading by sub-basin the Squam Lake watershed. Squam Lake Sub-Basin Cotton Cove Shadbush Livermore Cove Carns Cove Bennett Bennett 2 Smith Brook Eastman Brook Intervale Pond Kusumpe Barville Red Hill (Eagle Cliff) Kent lsland Dog Cove 2 Belknap Woods Dog Cove 1 (Laurel Is.) White Oak Pond Direct Shoreline Total Basin Area (ha) 91.73 179.47 316.80 123.92 160.94 204.44 708.59 405.55 517.70 130.64 721.12 128.27 98.06 217.99 295.44 437.78 1189.11 2681.63 8609.2 SQUAM LAKES ASSOCIATION Water Flow (cu.m./yr) 620184.95 1227840.21 2143906.80 838694.72 1090437.96 1383554.87 4751332.44 2739561.98 3450198.93 817217.47 4261605.27 865781.96 662990.98 1457089.06 1990034.23 2837726.39 7207100.58 18948539.09 57293797.9 TP Load (kg/yr) 4.27 13.75 17.18 7.25 6.85 10.57 23.73 17.21 21.98 5.15 39.01 4.91 3.96 17.88 20.05 47.32 70.81 269.03 600.9 Calculated TP (mg/L) 0.01 0.01 0.01 0.01 0.01 0.01 0.00 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.02 0.01 0.01 TP Load Per Hectare (kg/ha/yr) 0.05 0.08 0.05 0.06 0.04 0.05 0.03 0.04 0.04 0.04 0.05 0.04 0.04 0.08 0.07 0.11 0.06 0.10 1.0 31 SQUAM LAKES | WATERSHED MANAGEMENT PLAN Table 3-10: Phosphorus load estimates from the Lake Loading Response Model (kg/ha/yr) for Squam Lake. Source Atmospheric Internal Waterfowl Septic Watershed Load total Pre-Development 192.2 0.0 36.6 0.0 250.4 479.2 Current 302.0 13.2 36.6 168.6 600.9 1121.3 Future 686.5 33.0 36.6 678.9 1370.0 2805.0 Figure 3-9: Phosphorus load summary from the Lake Loading Response Model for Squam Lake. The relative contribution of septic systems greatly increases in the future model scenario (due to the large number of potential new buildings) and thus lowers the proportional loads from the watershed, atmospheric deposition, and waterfowl, but all loads (except waterfowl) greatly increase in load from the current model scenario. Table 3-11: Predicted and Measured in-lake total phosphorus (TP) concentrations for Squam Lake. Measured values are increased by 20% as an estimate for year-round in-lake phosphorus concentrations Scenario/Site Predicted Squam Lake pre-development Predicted Squam Lake current (2017) Predicted Squam Lake future (2148) Deephaven (measured +20%) Dog Cove (measured +20%) Piper Cove (measured +20%) Sandwich Bay (measured +20%) Median TP (ppb) 2.9 7.9 16.9 7.8 8.6 9.0 6.9 Little Squam Lake Watershed The direct shoreline area contributes the greatest annual phosphorus load to Little Squam Lake (Table 3-12). Most of the loading to Little Squam Lake comes from Squam Lake (Table 3-13). At full build-out, the amount of phosphorus entering Little Squam Lake will more than double (from 1,031 kg/ha/yr to 2,548 kg/ha/yr). At full build-out, the impact from the watershed (runoff and baseflow) and septic loading will increase proportionally (Figure 3-10). Septic and internal loading are rough estimates and will need further study to refine. SQUAM LAKES ASSOCIATION 32 SQUAM LAKES | WATERSHED MANAGEMENT PLAN Predicted in-lake phosphorus concentrations for Little Squam Lake were 7.6 ppb, and measured values for the lake’s deepest spot were 7.7 ppb (Table 3-14). Measured values were increased by 20% as an estimate for yearround total phosphorus concentrations. At full build-out, the LLRM predicts in-lake total phosphorus concentrations will be 18.7 ppb, which would put Little Squam Lake in the eutrophic trophic status. Table 3-12: Summary of land area, water flow, and total phosphorus (TP) loading by sub-basin the Little Squam Lake watershed. Little Squam Lake SubBasins North Brook Owl Brook Science Center Brook SE Little Squam South Little Squam 1 South Little Squam 2 South Little Squam 3 Direct Shoreline Total Basin Area (ha) 229.3 2172.4 75.8 95.4 139.4 78.4 42.5 549.3 3382.55 Water flow (cu.m./yr) 1,462,371 13,805,256 513,024 644,947 944,279 531,589 288,764 3,681,088 21871317.92 TP Load (kg/yr) 13.4 160.3 5.4 6.3 5.7 5.5 3.1 72.3 272.05 Calculated TP (mg/L) 0.009 0.012 0.010 0.010 0.006 0.010 0.011 0.020 TP Load Per Hectare (kg/ha/yr) 0.06 0.07 0.07 0.07 0.04 0.07 0.07 0.13 0.58 Table 3-13: Load estimates from the Lake Loading Response Model (kg/ha/year) for Little Squam Lake. Source Atmospheric Internal Waterfowl Septic Watershed Load Load From Big Squam Lake Total Pre-Development 11.9 0.0 6.8 0.0 98.2 225.0 341.9 Current 18.7 2.2 6.8 116.9 272.0 614.7 1031.3 Future 42.5 5.4 6.8 510.9 657.7 1323.4 2546.7 Figure 3-10: Phosphorus load summary from the Lake Loading Response Model for Little Squam Lake. The relative contribution of septic systems greatly increases in the future model scenario (due to the large number of potential new buildings) and thus lowers the proportional loads from Squam Lake and waterfowl, but all loads (except waterfowl) greatly increase in load from the current model scenario. SQUAM LAKES ASSOCIATION 33 SQUAM LAKES | WATERSHED MANAGEMENT PLAN Table 3-14: Predicted and measured in-lake total phosphorus concentrations. Measured values are increased by 20% as an estimate for year-round in-lake phosphorus concentrations Scenario/Site Predicted Little Squam Lake pre-development Predicted Little Squam Lake current (2017) Predicted Little Squam Lake future (2148) Little Squam Lake West (measured +20%) median TP (ppb) 2.9 7.6 18.7 7.7 3.4 Water Quality Goal The LLRM demonstrated changes in water quality as land cover changes with continued development of the watershed. Using the model results, we can make management decisions that will protect water quality in the Squam Lakes. Both Squam Lake and Little Squam Lake have in-lake phosphorus conditions that are within the State of New Hampshire’s oligotrophic criteria, and there is enough reserve capacity to assimilate the input of additional phosphorus as development increases; however, the build-out analysis and the results from the LLRM demonstrate that Squam Lakes are extremely vulnerable to new development. Thus, establishing a water quality goal that maintains current water quality better than the oligotrophic criteria is recommended to protect water quality into the future. The goal of the Squam Lakes Watershed Management Plan is to maintain current water quality in the Squam Lakes by reducing new or offsetting existing pollutant loading to Squam Lake and Little Squam Lake. To maintain current in-lake total phosphorus concentrations in the Squam Lakes, a total of 113.1 kg/yr of phosphorus load must be prevented, reduced, and/or offset in the Squam Lakes watershed (Table 3-15). This reduction is based on estimating the rate of development using the build-out analysis and using a compound annual growth rate to determine how much the projected phosphorus load will increase during the next ten years. Table 3-15: Total phosphorus loading (kg/yr) reductions necessary to achieve water quality goal. Lake Squam Lake Little Squam Lake Total Projected load increase from new dev in next 10 yrs [A] 78.7 34.4 113.1 Reductions possible from sites identified by watershed survey [B] 26.6 6.8 33.4 Further reductions needed [AB] 52.1 27.6 79.7 Fix high impact shoreline properties 33.4 19.1 52.5 Fix medium impact shoreline properties 17.9 8.1 25.9 Upgrade year-round shoreline septic systems 0.7 0.4 1.1 Upgrade seasonal shoreline septic systems 0.2 0.1 0.3 3.4.1 Pollutant Load Reductions Needed A variety of strategies will be required to meet the water quality objective in the next 10 years. Implementing structural BMPs from the watershed survey, future shoreline survey, and possible septic system upgrades will meet the water quality objective; however, achieving the water quality objective solely through structural BMPs will be resource intensive and will be more successful if non-structural BMPs are also used to address changes to zoning ordinances and to increase land conservation in the watershed. It is also important to note that, while the focus of the water quality objective is on phosphorus, the treatment of stormwater and sediment erosion will result in the reduction of many other kinds of pollutants (such as nitrogen, bacteria, road salt/sand, heavy metals, toxics, etc.) that may impact water quality. SQUAM LAKES ASSOCIATION 34 SQUAM LAKES | WATERSHED MANAGEMENT PLAN Watershed Survey A watershed survey conducted in May 2018 identified erosion hotspots in locations around the watershed. Erosion brings sediment and nutrients, including phosphorus, into surface waters. The watershed survey identified 53 practices around the watershed that will reduce phosphorus loading by 33.4 kg/yr into the lakes. Shoreline Phosphorus Impact A shoreline survey was not a part of the watershed planning process. Conducting a shoreline survey is recommended in the future to further understand the impact shoreline properties have on the water quality of Squam Lake and Little Squam Lake. Using the EPA Region 5 model, we can estimate the reduction in phosphorus loading from implementing best management practices (BMPs) along the shoreline (Table 3-16). We estimated that there are 35 shoreline properties on Squam Lake and 20 on Little Squam Lake that are high impact, requiring larger pro...