2012 Salmon Falls River TMDL Monitoring Report January 2013 FB Environmental Associates 97A Exchange St, Suite 305 Portland, ME 04101 2012 Salmon Falls River TMDL Monitoring Report January 2013 Table of Contents 1. Introduction ..............................................................................................................................................2 2. Description Of Study Area.......................................................................................................................2 3. Monitoring Program.................................................................................................................................2 4. Water Quality Monitoring Results ...........................................................................................................5 5. Compliance with Phased TMDL for the Salmon Falls River Watershed ..............................................12 6. Appendices ............................................................................................................................................ 14 Table of Figures Figure 1: Salmon Falls Watershed ...............................................................................................................3 Figure 2: Map of study area and water quality sampling points. .................................................................3 Figure 3: Map and photo of site SF16 in Somersworth, NH. ......................................................................8 Figure 6: Map and photo of site SF7 in Rollinsford, NH. .........................................................................10 Figure 7: Map of site SF5.1 in Rollinsford, NH. .......................................................................................10 Figure 8: Map and photo of site SF5 in South Berwick, ME. Photo taken at high tide. ...........................11 Figure 9: Map and photo of site SF4 in Rollinsford, NH. .........................................................................12 Table of Tables Table 1: 2012 sample sites and monitoring parameters for Salmon Falls River .........................................5 Table 2: Recommended water quality standards for Salmon Falls River (ME DEP, 1999) .......................6 i 2012 Salmon Falls River TMDL Monitoring Report January 2013 1. INTRODUCTION FB Environmental Associates (FBE) has been conducting seasonal (summer) compliance monitoring for the Salmon Falls River Phased Total Maximum Daily Load (TMDL) on behalf of the municipalities of Somersworth and Rollinsford, New Hampshire, and Berwick and South Berwick, Maine, since 2006. This sampling effort targets low-flow summertime conditions, defined as <114 cfs measured at Milton Three Ponds Dam gauging station, in Milton, NH. For the first years of monitoring, samples were collected from the same five locations in accordance with the Maine Department of Environmental Protection’s (ME DEP) 2006 Salmon Falls River TMDL Work Plan. Additional stations were added in later years. In 2009, frequent rain precluded sampling, as typical low-flow summer conditions were generally absent. ME DEP deployed water quality datasondes at two locations along the impaired segment, and this year FBE checked the temperature and dissolved oxygen profile at each datasonde sites to ensure proper depth. ME DEP can be obtained by contacting Barry Mower at 207-287-7777. 2. DESCRIPTION OF STUDY AREA The Salmon Falls River runs between Maine and New Hampshire for its entire length (~40 miles) originating from a series of lakes in Acton, Maine, and Wakefield, New Hampshire, and ending at the confluence of the Cocheco and Piscataqua rivers in South Berwick, Maine. The watershed covers approximately 330 square miles and encompasses 9 communities in New Hampshire and 10 communities in Maine (Figure 1, page 2). The 5.5 mile segment of the river that is the subject of the phased TMDL begins in Somersworth, New Hampshire, at river mile 3.3 and ends below the Hamilton House in South Berwick, Maine, at river mile -1.2. This lower part of the study area is tidally influenced. There are four dams in the study area: South Berwick (river mile 0.0), Rollinsford (river mile 1.1), Lower Great Falls (river mile 3.4), and Somersworth (river mile 4.9). Wastewater treatment plant discharges from Berwick and Somersworth flow into the Rollinsford impoundment, while the effluent discharged from Rollinsford and South Berwick flow into the South Berwick impoundment and just below the head of tide, respectively. 3. MONITORING PROGRAM The 2012 sampling was conducted at 7 locations during three sampling events: July 10, July 18, and July 26 (Figure 2). All samples were collected before 8 am, so that sampling occurred when dissolved oxygen (DO) was likely to be the lowest. All sites were accessed by canoe. All sites were monitored for total phosphorus (TP) and ortho-phosphate (ortho-P) using 2 meter integrated core samples. Sites SF16, SF11, SF7, and SF4 were also sampled for chlorophyll-a (Chl-a). Nitrogen compound samples included ammonia, nitrite-nitrate and Total Kjeldahl Nitrogen (TKN) and were collected for SF16, SF5.1, SF5, and SF4. All sites were monitored for pH, dissolved oxygen, and temperature. DO and temperature profiles were measured at 1 meter intervals for all sites, except SF5.1 and SF5 where depths generally only allow a surface measurement. Secchi disk transparency (SDT) was measured on a consistent basis at SF16, SF15, SF11, SF7 and SF4 (see Table 1 for a summary of parameters and sites). 2 2012 Salmon Falls River TMDL Monitoring Report January 2013 Figure 1: Salmon Falls Watershed Figure 2: Map of study area and water quality sampling points. 3 2012 Salmon Falls River TMDL Monitoring Report January 2013 4 2012 Salmon Falls River TMDL Monitoring Report January 2013 Field data sheets were used to document sample date, personnel, weather conditions, sample collection times, DO, temperature, salinity, meter calibration results, and meter cross check results (Appendix B). All water samples were placed in coolers on ice and delivered for analysis to the Maine Health and Environmental Testing Laboratory (HETL) in Augusta on the day they were collected (Appendix D). HETL chain of custody forms were used to document personnel, sample site, sample collection and delivery times, and other relevant information (Appendix C). Table 1: 2012 sample sites and monitoring parameters for Salmon Falls River NO2- Station TP1 PO4-P1 Chl-a1 NH32 TKN2 pH D.O. Temp. Salinity Secchi NO32 SF16 √ √ √ √ √ √ √ √ √ √ SF15 √ √ √ √ √ √ SF11 √ √ √ √ √ √ √ SF7 √ √ √ √ √ √ √ SF5.1 √ √ √ √ √ √ √ √ √ SF53 √ √ √ √ √ √ √ √ √ SF4 √ √ √ √ √ √ √ √ √ √ √ NOTES: 1. Two meter integrated core sample. 2. Surface grab. 3. Estimate flow. *Collect and vary duplicate each sampling event. 4. WATER QUALITY MONITORING RESULTS The complete Salmon Falls River water quality monitoring results for the 2012 sampling season are presented in Appendix A. Summaries for each site are provided below, along with comparisons to the ME DEP’s recommended water quality standards which include criteria for both Maine and New Hampshire (Table 2). The water quality goals for the Salmon Falls River require compliance with the more stringent standard of the two states and result in a single standard or goal that meets the objectives for both states. Barry Mower of Maine DEP provides the following summary of criteria applying to the Salmon Falls River: Higher levels of Chl-a resulting from excessive TP often result in excessive algal blooms and lower daily minimum dissolved oxygen in the early morning hours, both of which constitute non-attainment of water quality standards. Neither Maine nor New Hampshire have adopted numerical ambient water quality criteria for TP or Chl-a, but both have narrative language and draft or interim criteria that allow for requiring phosphorus controls on point and non-point source inputs in eutrophic waters. While the Maine DEP recommended a target range of 10 to 20 µg/L for Chl-a in the freshwater portion of the Salmon Falls River in the 1999 TMDL, recent data have led to draft criteria with a maximum of 10 µg/L and a spatial mean of 8 µg/L for each impoundment as thresholds not to be exceeded in freshwater impoundments in order to prevent nuisance blooms of blue-green algae 5 2012 Salmon Falls River TMDL Monitoring Report January 2013 that violate the narrative water quality criteria. Maine DEP has used a TP value of 35 µg/L as a best professional judgment ambient water quality threshold ( BPJ AWQT) for Class C waters for years. Draft TP ambient water quality criteria of 33 µg/L, which would be applied only in conjunction with water quality response variables such as Chl-a, will be proposed for adoption for Class C rivers and streams by rule in 2012. New Hampshire’s 2010 Consolidated Assessment and Listing Methodology for EPA’s 305b report lists interim Chl-a criteria for freshwaters (15 µg/L) and estuaries (20 µg/L). (B. Mower, personal communication, 1/19/2012). Chlorophyll-a exceeded 10 µg/L on 7/26/2012 at SF11 (18 µg/L) and SF7 (16 µg/L). All other Chl-a results were below 10 µg/L. NH DES has published recommended nutrient guidelines for Great Bay (2009). Those recommendations indicate a limit for total nitrogen (TN) concentration of 0.45 mg/L for aquatic life support by protecting DO. More stringent concentrations are listed for various water column depths to protect eelgrass. Calculated TN (sum of TKN and NO2-NO3) showed 9 of 13 samples exceeding or equal to 0.45 mg/L this summer,