04/03/2023 SELECT BOARD Minutes - Laserfiche WebLink

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.61 Mashpee Select Board Minutes April 3, 2023 Department..of Natural Resources Presentations: iJl date on the Mashl ee mWakeb�DWlostic Study Ed Eichne_r, TMDL Solutions School of Marineu Science and Technology ($MAST Uniyptsi t�f of MassachusettsaDartmouth: (continued) Miles Sundermeyer a professor at the UMass School for Marine Science was introduced to the Select Board. Professor Sundermeyer is assisting in the transition of the program to new leadership after the passing of Dr. Brian Howes to reaffirm the mission and work that continues to invest in the coastal resource program. The Town of Mashpee is in capable hands with a lot of resources. Santuit Pond Sediment Briefing Baseline Monitoring, Interim Measures Focused FeasibilitvAssessment Nutrient . Inactivation Dosing_StudN; Results: Matt„Ladewig TRCmConsultants: The Select Board met with Matt Ladewig of TRC Companies to review the results of the Focused Feasibility Study, Baseline Monitoring and Nutrient Inactivation Dosing Study to improve water quality in Santuit Pond. The purpose of the study was to evaluate and recommend the most appropriate measures for in -pond implementation over the short-term. Santuit Pond is highly nutrient -enriched with high phosphorus, low transparency, and high chlorophyll (algae). Findings reveal the dissolved oxygen depletion at the pond bottom allows the release of iron -bound phosphorus from sediments into the water. 78% of the annual phosphorus load derives from internal sources. Internal loading from sediments into the water column include septic and stormwater, etc. Management goals include the improvement of water quality by decreasing nutrient concentrations, reducing the duration and severity cyanobacteria blooms and the control of non-native aquatic plant growth. To facilitate the discussion and to address practical management measures, Santuit Pond was conceptually divided into three management zones. This includes; The Town landing and areas to the north, shallowest water, highest public visibility, one Solar Bee circulator, Bordered by Town landing to the north and Briant's Neck to the south, deepest water, highest resident visibility, three Solar Bee circulators, water quality sonde deployed in this area, and South and east of Briant's Neck, identified as potential dredge and fringe wetland restoration area, intermediate public and residential visibility, two Solar Bee circulators, near dam and fish ladder. The conceptual identification is based on present and physical characteristics, visibility, and the presence of existing management or monitoring infrastructure. Three in -pond restoration options are considered. This includes; Dredging — Not recommended and not feasible financially and technically. Circulation — Recommended Sediment Nutrient Inactivation — Recommended as most viable option to address internal phosphorus loading. Management options include multiple biological, chemical and physical approaches. The recommended options are most likely to be feasible and effective to the scale that is required. Aeration/Circulation Algaecides Nutrient Inactivation