Bacteria Monitoring
Background | What You Can Do | 2013 | 2014 | 2015 | 2016
2015 Save the Sound Bacterial Water Quality Data
Save the Sound sampling efforts were expanded significantly for the 2015 sampling season. With the aid of 24 trained volunteers, we collected approximately 400 water samples at 52 sites from Pelham, New York to Greenwich, Connecticut. We tested each sample for the fecal indicator bacteria Enterococcus and scored each sample as “pass” or “fail” based on the New York and Connecticut safe swimming criteria.
Explore the map below for a summary of each location. The colors reflect the average bacteria levels (the “geometric mean”), which gives a sense of how high the fecal contamination levels can get at each site. The “% Pass” and “% Fail” show how many samples passed or failed the single sample criteria for safe swimming.
Legend
Green = Passes safe swim criteria
Orange = Fails safe swim criteria
Red = Fails safe swim criteria by 10 times or more
Gray = Not enough data to calculate average (geomean)
Summary of Findings
We divided our data into three categories this year: river, embayment, and shoreline. River samples are collected in the tributary rivers, streams, brooks and creeks that flow into Long Island Sound. Embayment samples are those taken in recessed areas of the Sound coastline such as harbors. Shoreline samples are on the open coastline.
We also collected samples at four beaches, which are included in the “shoreline” or “embayment” categories as appropriate. To see historical data on all the beaches of Long Island Sound, visit our Sound Health Explorer.
Finding #1: Fecal contamination is high in the rivers, creeks, and brooks that feed Long Island Sound
River sites failed far more frequently and had the highest fecal contamination levels of the three site types. The overall failure rate of 79% is more than double the failure rate for the rivers category in 2014 (34%). This dramatic increase in failed samples is not attributable entirely to the rivers we added to the study this year. The rivers we sampled last year and again this year all had higher failure rates this season.
In 2014 20% of the samples from the Mamaroneck River and Sheldrake River failed the safe swimming criteria. In 2015 that number increased to 78%. Beaver Swamp Brook and Guion Creek went from a high 64% failure rate in 2014 to 95% in 2015.
The worst water quality in the study was found in our rivers.
Five Sites with the Highest Fecal Contamination Levels
Five Sites with the Highest Fecal Contamination Levels
We all clearly have a lot of work to do to clean up the waterways that run through our parks, by our schools, and flow into the Sound near our beaches.
Finding #2: All but one of the 2014 sample sites showed worsening water quality when tested again in 2015
We resumed sampling at many of the sites we sampled in the 2014 season. Only one of the sites we sampled last year showed improvement with a decreased failure rate—Sheldrake Lake. This site had no failing samples this year.
See 2014-2015 sampling result comparisons.
Finding #3: Sewage contamination is a highly localized issue. Some of the sites with the lowest fecal counts are located near sites with very high counts
The five cleanest sites in our study, in terms of fecal contamination levels, were located in Greenwich, Larchmont, and Mamaroneck Village. The site on Taylor Lane in Mamaroneck is part of Mamaroneck Harbor (the upper Northeastern extent of the larger Mamaroneck embayment). This site was our cleanest of the season even with some of the worst concentrations occurring under a mile away in the main portion of the harbor.
Fecal contamination tends to stay near the source and is disinfected by exposure to the sun (UV disinfection) and diluted by the tides the further it travels from the source. So if you don’t like the water quality in your neighborhood, look no further than yourself, your neighbors, and your local government to find sources and plan for improvements.
Five Sites with the Lowest Fecal Contamination Levels
Finding #4: Rainfall delivers pollution to our waterways
River, embayment, and shoreline sites all display better water quality during dry weather than wet weather.
Stormwater becomes contaminated with fecal matter in three ways. First, rain flushes animal waste and other pollutants from roads and curbside catch basins into our storm system and out to our beaches and harbors. Second, underground sewage leaks from cracked pipes and joints and failing septic systems mixes with stormwater and flow to the nearest waterway. And third, in large storms, overflowing sewer manholes—which are far too common in this area—spew raw sewage onto our roads. It then drains into the storm drains and ultimately to our waterways.
Pollution from stormwater can be dramatically reduced by letting rain be absorbed into the ground where it falls, instead of letting the majority of the rain scour hard surfaces, delivering excessively high amounts of rain and pollutants into our waterways. Green Infrastructure provides many strategies for increasing the recharge of rain water and decreasing stormwater runoff.
We can all take steps to improve the water quality in our communities!
Each one of us can help reduce sewage pollution sources simply by conserving water, which will lessen the wear-and-tear on our water infrastructure and reduce sewage overflows by lowering the volume of water in the system. Homeowners should maintain their septic systems and repair the sewer lines that connect homes and businesses to municipal sewers. (If roots get into your sewer line, sewage is probably getting out.) Sump pumps should discharge water onto lawns, not directly into a storm drain or catch basins. Dog owners should put pet waste in the trash, never in a catch basin or on the street.
Save the Sound encourages citizens to attend public meetings that address stormwater and sewage management. Reach out to your civic leaders if you’re concerned about sewage contamination observed in waterways in your community. Citizens informing themselves on this issue, opening discussions with municipal leaders, and showing support for solutions can be the first steps to curtailing unhealthy contamination of our waterways.
Be a Pollution Watchdog!
If you see sewage overflowing in your community, please let us know by sending a photograph or video and the time and location of the overflow to pollution@savethesound.org.
Background | What You Can Do | 2013 | 2014 | 2015 | 2016