Ossining sewage spill update as of Saturday evening August 13

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On Friday 8/12 Riverkeeper sampled from Irvington to Georges Island in response to the sewage spill entering the Hudson at Ossining due to a broken sewer main in Killbrook Creek. The Westchester Co Department of Health issued advisories on Thursday, the same day that they were notified of the discharge by Ossining. Riverkeeper’s goal was to measure the degree to which this discharge (stated to be 1.5 million gallons per day) was affecting surrounding waters in the Hudson.

See SUMMARY below data.

Notes:

• It is still not known exactly when the sewage release began.
• On Friday morning, when we began sampling, the tide was “flooding” at Ossining. Per NOAA tide current tables the flood started at 0734 and the ebb began at 1236 (at Ossining).
• The broken pipe was repaired in the late afternoon on Friday 8/12.
• The Federal (EPA) guideline recommends AGAINST primary contact with marine or brackish waters with an Enterococcus count of 104 (per 100 ml) or greater.

0750 – Killbrook Creek, above the tide
We first sampled in the creek itself, below the broken pipe and discharge but above the Hudson. Repairs had begun upstream. We used a 1/10 dilution as well as a 1/100 dilution to increase the maximum range of measurement.
Results: 1/100 dilution = >241,960 Entero per 100ml.
The creek was extremely impacted.

0815 – sample at Ossining, in the mooring area, near the waterfront park and launch ramp (about 300 yards south of the creek mouth).
Result: 74 entero per 100ml / “Acceptable” water quality.
Note: our highest measurement at this site (since 2006) was on 5/17/11: Entero count 4,611 per 100ml.

0825 – sample between channel buoys #15 and 16, approx 1 mile off Ossining.
Result: <10 entero per 100ml / "Acceptable" water quality. We do not regularly sample at this location. 0840 – sample on Rockland side at Nyack Beach in Hook Mountain Park.
Result: 10 entero per 100ml / “Acceptable” water quality. We do not regularly sample at this location.

0900 – sample at Nyack launch ramp at Memorial Park
Result: <10 entero per 100ml / "Acceptable" water quality. Note: our highest measurement at this site (since 2006) was also on 5/17/11: Entero count 663 per 100ml

0915 – sample at Philipse Manor Beach
Result: <10 entero per 100ml / "Acceptable" water quality. Note: our highest measurement NEAR this site (since 2006) was taken just south of the beach, near the mouth of the Pocantico River, and was also on 5/17/11: Entero count >24,196 per 100ml.

0928 – sample at Buoy # 8 off Tarrytown, just north of TZ Bridge
Result: <10 entero per 100ml / "Acceptable" water quality. Note: our highest measurement at this site (since 2006) was on 4/18/07: Entero count 252 per 100ml.

0940 – sample near fuel dock inside Tarrytown Marina
Result: 10 entero per 100ml / “Acceptable” water quality.
Note: our highest measurement at this site (since 2006) was also on 5/17/11: Entero count >24,196 per 100ml.

1000 – sample at Irvington, near beach and Boat Club float. Our southernmost sample.
Result: <10 entero per 100ml / "Acceptable" water quality. Note: our highest measurement at this site (since 2006) was also on 5/17/11: Entero count 120 per 100ml.

We turned back north.

1230 – sample at Croton Point Beach
Result: <10 entero per 100ml / "Acceptable" water quality. Note: our highest measurement at this site (since 2006) was also on 5/17/11: Entero count 169 per 100ml.

1305 – George’s Island near launch ramp. Our northernmost sample
Result: 20 entero per 100ml / “Acceptable” water quality. We do not regularly sample at this location.

Back to Ossining.

1530 – RE SAMPLE at Ossining, in the mooring area, near the waterfront park and launch ramp (about 300 yards south of the creek mouth).
Result: 85 entero per 100ml / “Acceptable” water quality.(count was 74 this morning)
Note: our highest measurement at this site (since 2006) was on 5/17/11: Entero count 4,611 per 100ml.

SUMMARY:
On 8/12, the creek in Ossining where the sewage discharge was occurring was extremely contaminated. Surprisingly, even 300 yards south of the creek mouth (approximately), at the Ossining Boat Club mooring area (near the launch ramp and riverfront park) Entero counts were 74 and 85 when sampled at 0815 and again at 1530 (both counts were “Acceptable”). All other sites from Irvington to George’s Island ramp and west to Nyack were not impacted and had “Acceptable” water quality per EPA guidelines.

Riverkeeper applauds the Westchester County Health Department for issuing advisories during the sewer main break at Ossining this week as well as the Village of Ossining which made short work of the repair in spite of the fact that the break took place in a location with very difficult access.

However, Riverkeeper has sampled at many of these same locations monthly since 2006. At a number of these sites we have measured very poor water quality, usually related to sewage overflows which chronically occur throughout the Hudson Valley during and after heavy rain events due to sewage infrastructure problems. See our historical data at:
www.riverkeeper.org/water-quality/locations

It is very important to note that the Westchester shoreline does suffer episodes of significant, sometimes extreme, sewage contamination. When these events occur there is usually no obvious cause, like a sewer main failure, and no warnings are given to the public. If we warn the public some of the time we need to warn them all the time.