Turkey River DRAFT Watershed Restoration August 2021 and Management Plan
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Turkey River DRAFT Watershed Restoration August 2021 and Management Plan Prepared for: Prepared by: Turkey River Watershed Restoration and Management Plan Acknowledgements Funding for this project was provided in part by a Watershed Assistance Grant from the New Hampshire Department of Environmental Services with Clean Water Act Section 319 funds from the U.S. Environmental Protection Agency. Funding support was also provided by generous contributions from supporters of the Upper Merrimack Watershed Association. i Turkey River Watershed Restoration and Management Plan Contents Introduction....………….….……...………………………………………………………………………….…………………1 1. Turkey River Water Quality Data ...................................................................................................... 4 1.1 SAMPLING DATA AND LOCATIONS .......................................................................................... 4 1.2 SUMMARY OF WATER QUALITY IMPAIRMENTS ..................................................................... 5 2. Water Quality Goals ........................................................................................................................... 7 2.1 WATER QUALITY GOAL SETTING - OVERVIEW ...................................................................... 7 2.2 PHOSPHORUS DATA AND RELEVANT CRITERIA ................................................................... 7 2.3 WATER QUALITY GOAL RECOMMENDATIONS ....................................................................... 9 2.4 SUMMARY OF WATER QUALITY GOAL SETTING MEETING ................................................ 11 3. Nutrient Load Modeling .................................................................................................................. 13 3.1 METHODS .................................................................................................................................. 13 3.1.1 Model Overview ................................................................................................................................ 13 3.1.2 Data Collection ................................................................................................................................. 13 3.1.3 Subwatershed Delineations .............................................................................................................. 13 3.1.4 Observed Water Quality Data........................................................................................................... 13 3.1.5 Model Inputs ..................................................................................................................................... 13 3.1.6 Buildout Analysis .............................................................................................................................. 18 3.2 CALIBRATION ............................................................................................................................ 19 3.2.1 Flow .................................................................................................................................................. 19 3.2.2 Nutrient Attenuation .......................................................................................................................... 19 3.2.3 Phosphorus Coefficients .................................................................................................................. 20 3.3 RESULTS ................................................................................................................................... 21 3.3.1 Phosphorus Loading by Source ....................................................................................................... 21 3.3.2 Phosphorus Loading by Subwatershed ............................................................................................ 22 3.4 SUMMARY OF FINDINGS ......................................................................................................... 25 4. Watershed Management ................................................................................................................... 26 4.1 STRUCTURAL BEST MANAGEMENT PRACTICES ................................................................. 26 4.1.1 Field Watershed Investigation .......................................................................................................... 26 4.1.2 Culvert Improvement Sites ............................................................................................................... 62 4.2 WASTEWATER MANAGEMENT ............................................................................................... 67 4.2.1 Background ...................................................................................................................................... 67 ii Turkey River Watershed Restoration and Management Plan 4.2.2 New Hampshire State Regulations ................................................................................................... 67 4.2.3 Septic System Risk Analysis ............................................................................................................ 68 4.2.4 Alternative Treatment Systems ........................................................................................................ 72 4.2.5 Recommendations for Wastewater Management ............................................................................. 74 4.3 NON-STRUCTURAL BEST MANAGEMENT PRACTICES ....................................................... 75 4.3.1 Public Information and Education ..................................................................................................... 75 4.3.2 Land Conservation ........................................................................................................................... 78 4.3.3 Regulatory Tools .............................................................................................................................. 81 4.3.4 Institutional Practices and Programs ................................................................................................ 83 5. Summary of Technical and Financial Support ................................................................................ 88 5.1 TECHNICAL SUPPORT ............................................................................................................. 88 5.2 FINANCIAL SUPPORT ............................................................................................................... 88 6. Schedule and Interim Milestones .................................................................................................... 91 7. Evaluation Criteria and Monitoring ................................................................................................. 93 7.1 EVALUATION CRITERIA ........................................................................................................... 93 7.2 MONITORING ............................................................................................................................. 95 7.3 ADAPTIVE MANAGEMENT ....................................................................................................... 95 iii Turkey River Watershed Restoration and Management Plan Figures Figure 1: Turkey River Watershed ................................................................................................................ 2 Figure 2. Total Phosphorus Measurements from Turkey River Mainstem Monitoring Stations ................... 4 Figure 3. Turkey River Watershed – Impairments to Designated Uses ....................................................... 5 Figure 4. Turkey River Watershed Impaired Parameters ............................................................................. 6 Figure 5. Estimated Total Annual Phosphorus Load from Land Uses ........................................................ 22 Figure 6. Estimated Increase in Annual Average TP Concentration per Subwatershed at Buildout .......... 24 Figure 7. Proposed Structural BMP Locations ............................................................................................ 28 Figure 8. Culvert Locations in the Turkey River Watershed ....................................................................... 65 Figure 9. Septic System Risk Analysis for the Turkey River Watershed .................................................... 71 Figure 10. Alternative Onsite System with Phosphorus Treatment (Source: EPA, 2013) .......................... 72 Figure 11. Land Conservation Areas for the Turkey River Watershed ....................................................... 80 Tables Table 1. Existing U.S. State and Territory Total Phosphorus Criteria .......................................................... 9 Table 2. Vermont WWMG TP and Aquatic Habitat Criteria ........................................................................ 10 Table 3. Potential TP Goals for the Turkey River ....................................................................................... 10 Table 4. Water Quality Goal Setting Meeting Participants (March 1, 2021) ............................................... 11 Table 5. Annual Precipiation Totals ............................................................................................................ 14 Table 6. Calculated Subwatershed Area .................................................................................................... 14 Table 7. LLRM Specified Land Uses .........................................................................................................