Bacteria Monitoring
Background | What You Can Do | 2013 | 2014 | 2015 | 2016
2014 Save the Sound Bacterial Water Quality Data
We focused our 2014 sampling efforts on the Mamaroneck Harbor Watershed (which includes Mamaroneck River, Sheldrake River, Beaver Swamp Brook, Otter Creek, and Mamaroneck Harbor), the Hutchinson River, and five Westchester beaches that are automatically closed in wet weather due to a history of contamination.
2014 Sampling Data
Summary of Findings
In the 2014 season we collected and analyzed 200+ samples, along with data provided by the Westchester County Department of Health, and arrived at these preliminary findings:
Finding #1: Fecal contamination is highest in the streams, creeks, and rivers that run through our communities and flow to our shorelines.
All samples from 2014 season scored based on
NYS single sample maximum criteria
We divided our samples into three categories: River, Harbor, and Beach. River samples were all collected in tributary rivers, streams, or creeks that flow into the Sound. Harbor samples include samples from beaches in the harbor, as well as non-beach harbor samples. Beach samples were taken off the swimming beach in knee-high water.
Not surprisingly, River samples failed frequently and as a group have the highest contamination levels. Our rivers, streams, and creeks collect runoff pollution from our communities, as well as contaminated groundwater, stormwater pipes, and other permitted discharges.
A very long list of rivers are already documented by NYS DEC, CT DEEP, and EPA as having unacceptably high levels of pathogen pollution in the Long Island Sound watershed, including these tributaries and ponds along the Westchester shoreline: Byram River, Blind Brook, Mamaroneck River, Titus Millpond, Burling Brook and tributaries, and Hutchinson River.
We need to work together with a watershed-wide approach to cleaning up these polluted tributaries and ponds. They run through our yards and parks and ultimately pollute our shoreline and beaches.
Finding #2: Rainfall is a common trigger of fecal contamination, causing spikes of pollution in Mamaroneck Harbor and nearby beaches.
Dry weather samples = less than ½” cumulative
rain in 3 days prior to sampling
Wet weather samples = more than ½” cumulative
rain in 3 days prior to sampling
Harbor and Beach water quality improves considerably in dry weather but suffers contamination spikes when it rains. These spikes reflect a combination of pollution sources including fecal-contaminated water from stormwater outfalls, polluted river water, and runoff from the surrounding landscape that delivers waste and debris directly onto beaches and into Mamaroneck Harbor.
Water flowing from stormwater outfalls becomes contaminated with fecal matter in three ways. First, overflowing sewer manholes, which are far too common in this area, spew raw sewage onto our roads which then enters our storm drains and waterways. Underground sewage leaks from old pipes and joints and failing septic systems also contaminate stormwater. Third, rain flushes animal waste from curbside catch basins into our storm system and out into our beaches and harbors.
Each one of us can help reduce these pollution sources by simply conserving water which will lessen the wear-and-tear on our water infrastructure and eliminate overflows. 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 then 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.
Finding #3: Beaver Swamp Brook shows the highest contamination levels in Mamaroneck Harbor subwatershed.
Sites with the five highest fecal contamination levels based on the geometric mean weighted average
We conducted repeat sampling at fourteen river sites—seven in the Mamaroneck River, three in the Sheldrake River, and four in Beaver Swamp Brook. We collected a combination of wet and dry samples at each location and calculated a geometric mean (GM) for each site to show relative levels of fecal contamination among the sites.
Beaver Swamp Brook and its downstream waterway, Guion Creek, had the top three sites for high fecal contamination levels. The counts are 7 to 17 times greater than the NY State limit for safe recreation (>200 cfu/100mL geometric mean).
On August 6, the Beaver Swamp Brook site near Rye Neck High School in Mamaroneck had the highest single sample in the Mamaroneck Harbor subwatershed study with a fecal coliform count of 15,000 cfu/100mL. This location had higher contamination levels on dry days than wet, pointing towards a potential 24/7 source of sewage that gets diluted in the rain. Further investigation is needed to find and eliminate the source.
The second highest count was in the Mamaroneck River at Columbus Park, just downstream from the confluence of the Sheldrake, on July 16, a fecal coliform count of 7,100 cfu/100mL.
Save the Sound is following up on these and other hot spots with local authorities.
Finding #4: The beaches have the lowest contamination levels in the study, with Coveleigh Beach passing 100% of the times tested.
We sampled at five beaches eleven times each, testing for fecal coliform in July and Enterococcus in August (both fecal indicators). Each month had two wet weather days and generally those were the days when we had samples fail. Those were also days when these beaches were closed by the Westchester County Department of Health (DOH), so public health was appropriately protected. All of these beaches are on the county wet weather closure list.
Most of the failed samples failed by a small margin; however there were a couple of outliers. Download data.
In July two beaches in Mamaroneck Harbor, Harbor Island Beach and Shore Acres, failed the NY State criteria (>200 fecal coliform cfu/100mL GM)., Harbor Island Beach also failed in August when tested for Entero (>35 Entero cfu/100mL GM). Entero is a more accurate indicator of disease-causing pathogens and the one used by Westchester County DOH.
The best results in the study come from Coveleigh Beach in Rye where every sample passed, even wet weather samples.
Why were Coveleigh Beach and some others that passed on wet weather days still closed by the county despite good water quality conditions? Because these water quality tests take 24 hours to incubate before you can score them and read the results. So the county, and Save the Sound, learn late the following day what the contamination levels were the day prior, at which point they have often changed. As a result, beach managers like the DOH have to make closure decisions based on historic trends at each location, resulting in a lag between improved water quality and changed management practices.
Sewage contamination tends to stay near the source. Diseasing-causing pathogens are disinfected by UV in the open environment and diluted by tides and flow. If you have fecal contamination in a waterway near you, look no further than your own community, and perhaps your own backyard, for the source and the opportunity to clean it up!
Look for Pollution!
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.
All summary findings are based on the New York State Recreational Water Quality Criteria
Background | What You Can Do | 2013 | 2014 | 2015 | 2016