08/28/2025 CONSERVATION COMMISSION Minutes

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Town of Mashpee Conservation Commission 16 Great Neck Road North Mashpee, MA 02649 as assessing the effects of raise and replace projects. He noted that using the viewer for Mashpee,particularly for Seconsett Island and Monomoscoy Island, shows that by 2050 some areas may be nearly submerged. He stressed that these are not speculative predictions but based on scientific probability. He referenced a recent Tulane University study analyzing 35 years of sea level rise data from 1990 to the present, which found that predictions made in 1990 were largely accurate and that actual sea level rise is, in some cases, occurring faster than those early models predicted. Mr. Colombo emphasized that when conditioning new homes in 2025, it is reasonable to assume that some properties may be underwater in 25 years. He noted that the data comes from reputable sources such as NASA and NOAA, although funding and data provision from these agencies have been cut back under the current administration. Despite this, international scientists continue to conduct and publish rigorous studies confirming similar projections. Mr. Colombo also discussed practical applications for the Commission, suggesting that the Morris Data Viewer can help evaluate the potential future impacts on property and septic systems. He indicated that both level one and level two tutorials are valuable, with level one providing general insights and level two offering in-depth technical analysis. He offered to share links to the tutorials as well as related articles he has been following, emphasizing the importance of using scientific data to inforin Commission decisions. Discussion • Regulation 30 (C) Prevention of Pollution: Impaired Water Body (Regulation 30 pertains to the Wetlands Protection Bylaw in Massachusetts municipalities. Each town may have its own version of Regulation 30, which outlines local rules and procedures for protecting wetlands and related resource areas beyond the state-level Wetlands Protection Act (M.G.L. c. 131, § 40) and its associated regulations (310 CMR 10.00).) The Commission reviewed ongoing concerns related to Regulation 30(C)—Prevention of Pollution, with a particular focus on impaired water bodies within the town. discussed Regulation 30, which deals with impaired water bodies, and how it relates to nitrogen loading calculations for projects within the town. Mr. Colombo noted that the Commission currently requires nitrogen calculations based on the Cape Cod Commission's 2019 Water Technical Bulletin, which sets a target concentration of 5 parts per million (ppm) for nitrogen. However, in practice, most projects, except for large wastewater systems like New Seabury, Willow Bend, or Mashpee Commons, are being designed to meet a 19 ppm limit, which he considers insufficient for protecting water quality. He emphasized that Regulation 30C gives the Commission authority to review projects on a case-by-case basis and impose stricter nitrogen limits if needed, though this has rarely been exercised. Mr. Colombo highlighted a discrepancy in calculations, as the Cape Cod Commission assumes 2.5 people per household, while a standard three-bedroom house legally houses six people. This reduces the calculated nitrogen output in official reports, potentially underestimating actual loads. He also pointed out that rainfall assumptions from the 2019 bulletin (19 inches/year) are no longer accurate due to climate change, affecting nitrogen mitigation estimates. Regarding IA (innovative/alternative) septic systems, it was explained that standard systems with filters often do not perform as intended, particularly if maintenance contracts are not followed. Homeowners may be unaware of maintenance requirements, and it is unclear how the Board of Health monitors long-term compliance, including after property transfers. He stressed that IA systems require consistent use to maintain a "aerobic environment" for bacteria or UV treatment to reduce nitrogen effectively.