Executive Summary. ES.1 Dennis Water Quality Issues. Dennis

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1 Executive Summary ES.1 Water Quality Issues The Town of currently faces threats to the health of its saltwater, freshwater, and groundwater resources. In recent years, excessive levels of nutrients, specifically nitrogen and phosphorus, have resulted in algal blooms in several of the town s surface water bodies. In 2009, an algal bloom occurred in Swan Pond creating aesthetically displeasing waters, fish kills due to depleted oxygen levels in the pond, and an odor that permeated the neighborhood for weeks. This event, as well as similar events at other area water bodies, was predominately caused by nitrogen originating from onsite wastewater systems (fully functioning Title 5 septic systems, cesspool systems, etc.) in the areas that contribute groundwater to the pond, referred to as the pond s watershed. Swan Pond is not alone in these problems. The Bass River and Herring River watersheds have also been identified as areas with high nitrogen sensitivity. Scargo Lake and other freshwater systems in town are facing similar issues, but due to excessive levels of phosphorus from similar sources. Without prompt and targeted actions, these problems will continue to worsen. As water quality declines, the tourist industry will decline as well. Waters that are periodically covered with mats of algae, that smell like decaying fish, and that do not support the ecology associated with the beauty of Cape Cod s waterways, will not draw an audience. Tourists and residents alike will be drawn to other locations. Property values and tax revenues in coastal areas will decline, and the burden of maintaining town services will shift inland, to those who can least afford it. Thus, it is imperative for Cape Cod communities like to deal with these water quality issues before irreparable economic and quality of life damage is done. Algae Bloom in Swan Pond 1

2 Executive Summary Water Quality Evaluation and Mitigation Alternative Study ES.2 Water Quality Study In recognition of the importance of preserving, restoring, and maintaining high-quality water resources, the Town of Comprehensive Wastewater Management Task Force has undertaken this Water Quality Evaluation and Mitigation Alternative Study. This project builds on prior work and, in the next phase of study, will culminate in the development of a town-wide plan to guide future decision making as it pertains to water quality initiatives. Scargo Lake and Cape Cod Bay Sesuit Harbor This portion of the study is divided into two major phases. This first phase (Water Quality Evaluation) includes analysis of existing water quality data and presentation of the results. The second phase (Mitigation Alternative Study) evaluates options for mitigating the water quality issues identified under the first phase and develops, evaluates, and screens them, to arrive at four feasible options to be carried forward for more detailed consideration. Future phases will evaluate the four selected options in more detail and develop a recommended program to meet the short- and long-term water quality needs of the community. ES.3 Summary of Water Quality Evaluation Results The Water Quality Evaluation includes evaluations of saltwater estuaries and embayments, freshwater ponds, drinking water supplies, and recreational beaches in. The locations of the water resources examined are shown on Figure ES-1, and the results are summarized below. ES.3.1 Saltwater Estuaries and Embayments Figure ES-1 shows the locations of the saltwater estuaries and embayments in. Five of the town s six embayments are included in the Massachusetts Estuaries Project (MEP), as shown in Table ES-1 below. Estuary/Embayment Watershed Location MA Estuaries Project Status Bass River, Yarmouth, Brewster Final Report Completed April 2011 Swan Pond River Predominately Final Report Completed October 2012 Herring River Harwich, Brewster, and Final Report Completed March 2013 Chase Garden Creek and Yarmouth Report in Progress Sesuit Harbor Report in Progress Quivett Creek Brewster and Not included in MEP Table ES-1 Saltwater Estuaries and Embayments in The MEP results determine the acceptable levels of nitrogen that can be discharged to each watershed while maintaining a healthy water environment. These results are presented in two parts: 1) the amount of total controllable nitrogen requiring reduction in order to meet water quality goals, and 2) the 2

3 Water Quality Evaluation and Mitigation Alternative Study Executive Summary August 2015Au August

4 Executive Summary Water Quality Evaluation and Mitigation Alternative Study amount of septic system nitrogen reduction required to meet those same goals. Controllable nitrogen includes sources such as stormwater runoff, fertilizer use, and leachate from landfills, in addition to wastewater. While addressing septic system nitrogen may be the most straightforward means of quantifiable nitrogen reduction, it is not the only option. Therefore, by presenting these two values for each watershed, a range of options to deal with nitrogen reduction can be considered. The results for each watershed with a completed MEP study are presented in Table ES-2. Note that within each watershed shown, reduction percentages vary widely from one sub-watershed to another. Breakdowns by sub-watershed can be found in Section 2 of the report and must be considered in the development of options to achieve required nitrogen reduction goals. Typically, watershed areas farther upstream require higher nitrogen reduction, while the areas closer to the ocean and those that experience a greater degree of tidal flushing require less intervention. MEP Watershed Total Controllable Load Decrease to Meet Threshold (% change) MEP Scenario Septic Load Decrease to Meet Threshold (% change) Bass River -47.4% -59.5% Swan Pond River -75.5% % Herring River -23.6% -38.5% Table ES-2 Decrease in Present Attenuated Loading to Meet Nitrogen Thresholds ES.3.2 Freshwater Ponds As noted above, freshwater ponds are typically threatened by excessive levels of phosphorus, which is typically the limiting nutrient in freshwater systems. This means that small increases in phosphorus above typical background levels can spur unwanted growth of algae, which in turn can decrease oxygen levels in the bottom layers of a pond, especially during the warmer months. Scargo Lake and Cape Cod Bay Eleven of freshwater ponds are sampled routinely as part of the Cape Cod Pond and Lake Stewardship (P.A.L.S.) program. Ten years of historic data from these sampling events were examined as part of this evaluation, along with more detailed data from site-specific studies at particular ponds. From this information, six ponds were identified as having impaired water quality: Cedar Pond, Coles Pond, Fresh Pond, Hiram Pond, Run Pond, and Scargo Lake. Of these six ponds, all except for Run Pond have medium to high density shoreline development which contributes to water quality impairment. Therefore, nutrient reduction methods will be considered for the watersheds to these ponds in the development of a recommended program for water quality improvements moving forward. 4

5 Water Quality Evaluation and Mitigation Alternative Study Executive Summary ES.3.3 Drinking Water Supplies Water District s drinking water supplies were evaluated in terms of both overall water quality and nitrogen levels. The overall quality of groundwater supplies was found to be very good, with no measurements exceeding federal Safe Drinking Water Act standards over the last five years. Nitrate (nitrogen) levels were examined both in relation to public health impacts and as an indicator of wastewater and stormwater influence on town drinking water supplies. Regulatory thresholds for nitrate in drinking water include a 10 mg/l limit according to the Safe Drinking Water Act and a 5 mg/l goal established by the Cape Cod Commission. None of Water District s 22 wells have exceeded either of these nitrate levels in any single sample in the 22-year period examined (1993 through 2014). Furthermore, none of the town s wells have exhibited a trend of steadily increasing nitrate over time. Average nitrate levels over the period examined were below 1.0 mg/l in thirteen of the town s wells, between 1.0 and 2.0 mg/l in six wells, and between 2.0 and 3.0 mg/l in three wells. It is worth noting that these public health-related nitrate thresholds (5 and 10 mg/l) are much higher than the thresholds established for healthy estuarine ecosystems (typically 0.5 mg/l or less); therefore, it is common to meet drinking water standards while still greatly exceeding the nitrogen levels in groundwater required to protect the saltwater environment. ES.3.4 Recreational Water Quality The Massachusetts Department of Public Health (MDPH) administers the Beach Program for all beaches in the Commonwealth. Beaches are sampled regularly for bacteria during the swimming season, at a frequency based on historic beach water quality. has a mix of saltwater beaches at the shorelines and freshwater beaches at ponds. The sampling frequency for all beaches in is weekly. This sampling is solely for the purpose of evaluating the public health risks of contact recreation and therefore focuses on bacteria levels only. Similar to the drinking water standards noted above, meeting recreational (bacterial) water quality standards does not equate to meeting the nutrient levels necessary for a healthy ecosystem. Sesuit Harbor Beaches along Nantucket Sound has 23 marine beaches and three freshwater beaches that are tested as part of this program. Five years of beach sampling results were examined for this study, from 2009 through 2013, with between 13 and 18 sampling events per year. Each beach was thus subject to roughly 70 sampling events over the five-year period. Of the three freshwater beaches tested, all tests met the required bacterial standards. At the saltwater beaches, only one beach met the required levels in all samples (West Beach), while 21 beaches had between one and four measurements above the regulatory thresholds. The remaining two beaches, Bayview and Clipper Lane, had five and 11 measurements above the regulatory thresholds, respectively. 5

6 Executive Summary Water Quality Evaluation and Mitigation Alternative Study Therefore, recreational water quality has largely been in compliance with regulatory standards. Isolated instances have occurred where the bacterial limits have been exceeded, usually in response to a stormwater discharge after a rainfall event. However, these have not typically resulted in beach closures, since the present regulations allow many beaches to remain open if a sample the following day is tested and found to be in compliance with regulatory thresholds. ES.4 Mitigation Alternative Study ES.4.1 Updated Needs Assessment The second phase of this water quality planning project began with an updated needs assessment, to combine the results of the Water Quality Evaluation with a prior needs assessment completed by the town in The 2005 study focused on wastewater needs, specifically where onsite septic systems were deemed problematic either due to difficulty complying with The State Environmental Code (Title 5) or other considerations such as proximity to public drinking water supply wells. The updated needs assessment was expanded to also include consideration of areas in where economic development or planned growth is desired but is presently limited by a lack of sufficient infrastructure, such as the growth and resort districts designated by the town s Planning Department and Planning Board. Figure ES-2 summarizes the results of the updated needs assessment, showing the needs identified in this Water Quality Evaluation, updated outlines of the needs areas (Areas of Concern) arising from the 2005 study, and the town s designated planning districts. Sesuit Harbor The conclusion of the updated needs assessment is that nitrogen reduction in the MEP-designated watersheds presents the greatest need in terms of an immediate threat to the town s environmental resources. Specifically, the Bass River, Swan Pond River, and Herring River watersheds, all identified as over-enriched and impaired, will be required by the state and federal governments to meet water quality standards. Total Maximum Daily Loads (TMDLs) will be established by regulators for each watershed that had an MEP study conducted. These TMDLs will be enforced consistent with provisions of the federal Clean Water Act. ES.4.2 Coordination with the 208 Plan The Cape Cod Commission s Area-wide Water Quality Management Plan Update ( the 208 Plan ) has been developed to address these same federal regulatory requirements. The 208 Plan discusses the nitrogen problem Cape-wide and presents a suite of options towns can consider in solving their nitrogen loading issues. The 208 Plan s recommendations are based on meeting the goals outlined in each MEP report. The Cape Cod Commission has designated each Cape Cod town as the Waste Management Agency responsible for meeting the Clean Water Act requirements for water resource protection. 6

7 Water Quality Evaluation and Mitigation Alternative Study Executive Summary Cape Cod Bay Cold Storage Beach Corporation Beach SESUIT HARBOR Chaplin Memorial Beach Mayflower Beach DENNIS Sesuit Harbor TBD by MEP Quivett Creek Not Included in MEP Chase Garden Creek Assumed 0% BREWSTER Bass River SETUCKET ROAD Herring River Swan Pond River HARWICH YARMOUTH BASS RIVER SWAN POND Legend Area of Concern MEP Watershed Delineations Planning Districts Zone II SWAN POND RIVER Pond Water Quality High Water Quality Impared Water Quality No PALS Data Raycroft Beach Proposed Controllable Nitrogen Removal from MEP to Meet TMDL 80-90% 50-60% 70-80% 0% West Beach South Village Beach Sea Street Beach Nantucket Sound N Town of, MA Water Quality Evaluation and Mitigation Alternative Study August in = 4,500 ft Miles Summary of Water Quality Management Needs Figure ES-2 7

8 Executive Summary Water Quality Evaluation and Mitigation Alternative Study ES.4.3 Development of Scenarios for Water Quality Improvement With the primary goal of meeting the MEP nitrogen reduction requirements, the town developed 14 scenarios for water quality improvements. A secondary goal was maintained throughout the scenario development of targeting improvements in areas that also had high levels of needs for other reasons (e.g., areas exhibiting an historic lack of Title 5 compliance, watersheds to impaired ponds, locations within planning districts, etc.). Route 6 Bridge over Bass River The 14 scenarios combine both traditional (sewering) and non-traditional nitrogen reduction technologies. The Comprehensive Wastewater Management Task Force began with the full range of technologies presented by the Cape Cod Commission in the 208 Plan and narrowed the options to those that showed the most promise for. This decision included consideration of historic practices in, community acceptance, long-term sustainability, and costs. The range of options was narrowed to focus on the following primary components: aquaculture, innovative/alternative (I/A) onsite septic systems, permeable reactive barriers, stormwater management, fertilizer use education, and both decentralized and centralized sewer systems. In addition to this list of the most favorable options, other technologies were also kept in play such as bridge widening at Route 6 (Bass River), floating constructed wetlands for in situ nutrient treatment, in-lake mixing or aeration options for freshwater ponds, and ecotoilets in select locations. Table ES-3 summarizes the components of the scenarios examined. Table ES-3: Nitrogen Reduction Technologies Scenario # Fertilizer Education Stormwater Treatment Aquaculture (total acres) Onsite I/A Systems (# Parcels) Decentralized Sewers (# Parcels) Centralized Sewers (# Parcels) Wastewater Treatment (# of Facilities) Effluent Recharge Sites (# Locations) Permeable Reactive Barrier at Recharge Site Ocean Outfall 1 P P 6,900 2A P P 28 6,500 3A P P , P 3B P P , P 4A P P 5, P 4B P P 5, P 5A P P 9.5 5, B P P 9.5 5, A P P , P 6B P P , P 7A P P 5 8, P 7B P P 5 8, P 7C P P , P 7D P P 8,300 1 P Scenarios selected for further evaluation 8

9 Water Quality Evaluation and Mitigation Alternative Study Executive Summary At this time, all scenarios focus on existing development and will later be modified to consider buildout. Scenario 1 (all onsite I/A systems) was determined to not be able to meet the MEP goals, and Scenario 2 shows that a substantial acreage of aquaculture would need to be added to Scenario 1 to arrive at a solution that does not involve any sewering. Scenarios 1 and 2 have substantially higher annual operations and maintenance (O&M) costs than the scenarios that rely less heavily on onsite I/A systems, resulting in equivalent annual costs (annual capital loan repayment costs plus O&M costs) that far exceed any of the sewering options examined. This analysis shows that scenarios that favor non-traditional technologies are not necessarily less costly. Therefore, the town is attempting to strike the appropriate balance using sewering only where absolutely necessary to cost-effectively and sustainably meet the MEP goals, supplemented with non-traditional technologies in logical locations to make up the difference in required nitrogen reduction. ES.4.4 Evaluation and Screening of Scenarios An evaluation matrix was created to allow the Task Force to screen the 14 scenarios down to the four most favorable options. Eighteen evaluation criteria were considered and weighted, fitting into four categories: relative costs, technical criteria, institutional criteria, and environmental criteria. Costs were weighted the most heavily, comprising 50 percent of the scoring. Ultimately, the scenarios were screened to four options, referred to as Scenarios 3B, 5A, 5B, and 6B. Table ES-3 and Figure ES-3 illustrate the combinations of sewering and non-traditional technologies utilized in these four scenarios. The total capital costs of the selected scenarios range from approximately $185 to $220 million. Annual O&M costs range from $5 to $7 million. As shown on Figure ES-3, each scenario includes one to two preferred sites for wastewater treatment and treated effluent recharge. These sites were selected via a detailed site screening process considering environmental impacts, sensitive receptors, and input from town officials. ES.5 Next Steps The full version of the Water Quality Evaluation and Mitigation Alternative Study can be downloaded at: Pages/MA_BComm/ wastewater/wastewater Ultimately, the town will select a recommended program for implementation that provides a solution for each impaired watershed, while addressing other town goals where practical and economically feasible. This process will include coordination with surrounding towns with which watersheds are shared. The final recommended program will be put forth to the town and to regulatory agencies, including the Massachusetts Department of Environmental Protection and the Cape Cod Commission. This plan will include an adaptive management approach, whereby water quality will continue being monitored throughout the implementation phase to determine if improvements are realized over time, and adjustments can be made to the plan as necessary to ensure that water quality goals are ultimately met. Become Involved Public input on the evaluations to date and the options moving forward is requested and encouraged. Residents and stakeholders can become involved by adding their address to the Task Force s mailing list at 9

10 Executive Summary Water Quality Evaluation and Mitigation Alternative Study Cape Cod Bay SESUIT HARBOR 6A! ( BREWSTER Ai rlin e 134 U V Ro ad Setucket Road HARWICH Aquaculture Minimum: 0 Acres Maximum: 3.5 Acres 6 YARMOUTH et Stre Main 6 te t Wes Grea ad rn Ro Aquaculture Minimum: 2.75 Acres Maximum: 7.75 Acres 134 U V p Up n ou Depot Street C er R ty d oa 28! ( Nitrogen Reduction Options Parcels with Possible Sewers er Co Low Parcels with Possible I/A Systems R unty oad Parcels with Sewers or I/A Systems Depending on Scenario Aquaculture Nantucket Sound Possible Treatment & Recharge Sites N Town of, MA Water Quality Evaluation and Mitigation Alternative Study August in = 4,500 ft Summary of Scenarios for Further Evaluation Figure ES-3 Miles