LAKE MASSAPOAG
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2022 Lake Water Testing

Overview: Lake Massapoag's Memorial Beach and other swimming beaches had good water quality in 2022, with the exception of Community Center Beach. This Dashboard summarizes the progress we are making in identifying hot spots for E. coli and phosphorus, which will help inform future recommendations for source reduction, plans for mitigation, and infrastructure projects to improve lake health.

Phosphorus and E. coli testing at lake inlets
Because cyanobacteria blooms are often fed by excess phosphorus, in 2022 LMAC added testing of phosphorus levels at inflow sites, on a monthly basis from June through September. Detailed results can be found here (top and middle table on left).  Samples were collected by town staff and volunteers, and phosphorus analysis performed by a professional lab.  Some water samples were collected during and after rainstorms, to capture the impact of runoff.  Several of the inflows showed high levels of phosphorus during the summer, especially during or after rain a significant rainstorm.  This map shows the testing sites for inflows.  2022 E. coli test results for swimming beaches can be found here.  ​

​Neponset River Watershed Association (NepRWA) testing of Sucker Brook
New for 2022, NepRWA  added a Lake Massapoag site, Sucker Brook which is the main inflow into the lake, to its Community Water Monitoring Network (CWMN). ​The results are here, (bottom table on left).
​Volunteers collected monthly water samples May-October for analysis of E. coli, total phosphorus, dissolved oxygen, pH, chlorophyll-a, and water temperature. NepRWA also did a hot spot analysis of Sucker Brook, testing for phosphorus and potential sources of pollution, as this brook enters the lake near the Community Center Beach, which has been the most problematic site for high E. coli.  For data on all of NepRWA's CWMN sites, click on the interactive map here. 

Comprehensive Professional Lake Water Quality Testing 
We used a professional environmental services firm to obtain a snapshot of multiple lake water quality parameters (results to date can be found here) in the deep hole of the lake, monitoring the water column from the surface to the lake bottom, during the late spring, mid summer, and early fall.  Similar testing was done in the south and west coves.  The Lake’s Deep Hole, Fletcher’s Cove, and South Cove showed high phosphorus levels in early June.  

Cyanobacteria Testing
In 2022 LMAC, in consultation with EPA biologist Hilary Snook, began weekly testing of the deep hole for cyanobacteria. See detailed 2022 Cyanobacteria Test Results here.  Microscopy was used  to identify specific genuses of cyanobacteria, which is important because different genuses produce different toxins.  A fluorometer was used to measure the levels of phycocyanin, a protein produced by cyanobacteria, as an indicator of the levels of cyanobacteria present.  Levels of cyanobacteria in the deep hole were low all summer, and only one bloom was reported on Sept. 9, and it cleared quickly.    Learn more about cyanobacteria here. ​

Historical Data
A comprehensive Diagnostic/Feasibility Study: Lake Massapoag in 1984 provides helpful background, historical data on lake water quality, and options and recommendations for implementation. Without action, the lake was predicted to be eutrophic (dead) by the year 2000. Many actions were taken, gaining many years of lake health. Today, excess nutrients, stronger storms, runoff, etc. threaten the lake.
 
Future
LMAC seeks to develop and implement a new plan for 2024-2050. Sustained effort and investments to safeguard lake water quality, limit excess nutrients, harmful bacteria, and invasive weeds will be needed for several years, as more intense weather associated with climate change increase the impact of excess nutrients, rain, runoff and heat.
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  • Home
    • E. coli & Beach Closures
    • Lake Levels
    • 2022 Lake Water Testing
    • History & Geology
  • Recreation
    • Special Events
    • Rules
  • Threats
    • E. coli
    • Cyanobacteria
    • Invasive Species
    • Climate
  • Protect
    • What Can I Do? Top 10
    • Lakefront & Watershed
    • Septic
    • Lawn Care
    • Outdoor Washing
    • Stop Invasive Species
  • Contacts
  • 2022 CB Testing
  • Search