Nine beaches along Westchester County's Sound Shore are closed through the weekend after 3.28 inches of rain swept through the region, triggering automatic health closures just hours after a nearby treatment plant dumped an estimated 5 million gallons of partially treated sewage into Long Island Sound. The Westchester County Department of Health announced the closures affecting beaches in New Rochelle, Mamaroneck, and Rye, warning that bacterial contamination has made the water unsafe for swimming until further notice.
According to Daily Voice, heavy rainfall can wash bacteria and other contaminants from roads into drainage outfalls near beaches, and county health officials have advised beachgoers to simply stay out of the water. The closures span Hudson Park Beach, Davenport Beach Club, Greentree Country Club, and Surf Club on the Sound in New Rochelle; Harbor Island Park, Beach Point Club, Orienta Beach Club, and Mamaroneck Beach & Yacht Club in Mamaroneck; and Coveleigh Club in Rye. Officials said the beaches will remain shut through the weekend and until further notice as the county continues working to maintain environmental health and safety standards at its recreational facilities.
Storm Triggers Automatic County Shutdown Rules
The closures were not discretionary. Under Westchester County Department of Health protocols detailed by The Rye Record, beaches in protected Sound Shore coves must automatically close for one day after more than half an inch of rain and for two days after more than an inch, with longer closures for anything above 2 inches determined by water clearance testing. With 3.28 inches recorded on August 20, the shutdown falls into that extended category, pending official testing before any of the nine beaches reopen.
Those thresholds exist because New York State Sanitary Code Subpart 6-2 requires local health departments to monitor public bathing beaches for fecal indicator bacteria and issue immediate closures whenever water quality fails to meet state limits, per the state Department of Health. The state's safe-swimming ceiling for enterococci bacteria in marine waters is 104 colony-forming units per 100 milliliters. Post-storm samples at Rye beaches earlier this summer registered far higher, hitting 882 CFU at Rye Playland Beach and 638 CFU at Coveleigh Club, the same article notes.
A Sewage Plant Overwhelmed the Night Before
The timing of this weekend's closures lines up with a major release just upstream. On the evening of August 20 — before the closures were announced — the Mamaroneck Sanitary Sewer District Wastewater Treatment Plant discharged an estimated 5 million gallons of partially treated, disinfected sewage into the Sound after storm flows overwhelmed the facility's processing capacity, the Rye Record reported. The plant sits adjacent to Harbor Island Park, one of the affected beaches.
That single discharge pushed the plant's total releases for August alone to nearly 10 million gallons, following a 4-million-gallon release on August 3 and a 536,000-gallon release on July 21, according to the same outlet's reporting. The Mamaroneck plant, located at 199 West Boston Post Road, is in the middle of a multi-year renovation, and facility rules require noncompliance reports whenever storm flows exceeding 28 million gallons per day bypass secondary treatment — a threshold heavy rain keeps pushing past.
Third Closure of the Summer Fits a Wider Pattern
This is the third time in a matter of weeks that Westchester has shut down the same nine Sound Shore beaches. MyRye.com reported that earlier multi-day closures followed 1.8 inches of rain on July 19 and 1.76 inches on August 4 — closures Hoodline covered in late July.
The recurring shutdowns track with what environmental group Save the Sound has documented regionally. Its 2025 Long Island Sound Beach Report found that 11 of the 16 lowest-scoring beaches across the entire Sound were in Westchester County or New York City, with Mamaroneck Beach & Yacht Club earning an F grade after 35% of its samples failed safety standards — a finding Hoodline detailed in its report card coverage in May. Wet-weather sample failure rates at Westchester and New York City beaches hit a record 20.8% during the 2024 monitoring season, driven by stormwater runoff and leaky municipal sewer pipes, according to Save the Sound data reported by Daily Voice.
Legal Settlements Loom Over Aging Infrastructure
Save the Sound previously reached Clean Water Act settlements with Westchester County and 11 Sound Shore municipalities, including Rye and Mamaroneck, over allegations that leaky municipal sewer lines allowed untreated sewage to reach the Sound, MyRye.com reported. Those settlements require long-term sewer system upgrades, but with construction still underway at the Mamaroneck plant, storm inflows above the 28-million-gallon threshold are expected to keep forcing partial sewage bypasses for years to come. For now, county health officials say the nine beaches will stay closed until testing confirms the water is safe again.
