Massachusetts Water Resources Authority. MWRA Advisory Board March 22, 2013

Transcription

1 Massachusetts Water Resources Authority Mystic River Water Quality MWRA Advisory Board March 22, 2013

2 Water quality issues in the Mystic River watershed Eutrophication-excess nutrients Invasive species Contamination in fish and sediments Structural impacts on fish passage Low flow Pathogens Measured as sewage indicator bacteria Fecal coliform, E. coli, Enterococcus EPA grades based on bacteria only Top: water chestnut growth in river Bottom: Harvesting invasive water chestnuts in the Mystic Note backyard turf to water s edge 2

3 Water Quality Sampling in the Mystic River Watershed: Complementary Designs Watershed Association (green dots) 15 baseline sites throughout watershed: brooks, lakes, inner harbor Hotspot monitoring of outfalls, varies each year MWRA (red dots) focuses on main stem and Alewife Central Lab analyzes samples from MyWRA baseline and MWRA 3

4 Watershed Association (MyRWA) Results: Upper Mystic Lake and Mystic main stem generally meet bacteria swimming standard 4

5 MWRA results: Except after heavy rain and in Alewife Brook, most river samples meet standard Geomean standard = 33 cfu 5

6 data for bacteria are similar for Mystic River and Lower Charles Mystic River: percent of samples meeting Enterococcus State standard 100% 80% 80% 86% 96% 60% 40% 20% 42% 0% All weather Heavy Rain Light Rain Dry/Damp % samples meeting 104 col/100 ml beach posting standard Heavy rain impacts both water bodies, both are good in dry weather 6

7 Average bacteria counts 2011 in different reaches of both rivers Alewife Brook and Mystic River Enterococcus Swimming standard d (geomean) Lower Charles River Enterococcus Swimming standard (geomean) 7

8 Comparison of Lower Charles and Mystic River main stem over time, Geometric Mean Enteroco occus Lower Charles Mystic River mainstem State swimming standard While the Charles suffered severe bacterial contamination in the late 1980 s through the 1990 s, the Mystic was never as seriously impacted. 8

9 MWRA s Long Term CSO Control Plan MWRA has completed many CSO control projects in the broader Mystic River Watershed. Overall, MWRA has spent approximately $174.7 to date. Some representative projects include: East Boston Branch Sewer Relief - $85.7 million Chelsea Sewer Replacement & Relief - $29.8 million Storage at BOS019 - $14.3 million Upgrades to the Somerville Marginal Treatment Facility - $4 million 9

10 MWRA s Long Term CSO Control Plan-Alewife Brook Of the $174.7 million spent to date, MWRA has $38.4 million on Alewife Brook projects and Cambridge has spent an additional $39 million on sewer separation, floatables control and the CAM004 stormwater outfall and wetland basin. MWRA expects to spend up to an additional $52.7 million and Cambridge up to an additional $40.9 million to complete the remaining Alewife work by the end of

11 Other MWRA Infrastructure Improvements MWRA has spent approximately $11.4 million to rehabilitate and optimize wastewater infrastructure in the watershed. Cummingsville Branch Sewer Replacement and Rehabilitation- Winchester Wedgemere Siphon Relocation - Winchester Mystic Valley Sewer Rehabilitation-Winchester Section 156 Rehabilitation- Everett Melrose Sewer Improvements 11

12 Somerville Marginal Investigations MWRA worked closely with EPA and the City of Somerville to address potential dry weather bacteria sources from the Somerville Marginal outfall pipe. Improvements at the Somerville Marginal Facility included: installation of two main influent sluice gates four sets of stop logs two channel dewatering pumps to maintain air gap between the influent channel and the Somerville Marginal Conduit in dry weather. Completed in 2011 at $364,

13 MWRA Community Support Program MWRA s Community Support Program has provided communities in the Mystic River Watershed $ million in grants and loans to rehabilitate and modernize the local wastewater systems. 13