Danny Davis -- Ashokan Watershed Stream Management group tours sites throughout NW Ulster Co.

Ashokan Watershed Stream Management group tours sites throughout NW Ulster Co.

Friday, December 9, 2011

State and county officials toured the Ashokan watershed by bus Friday morning, to inspect flood mitigation projects performed by the Ashokan Watershed Stream Management Program (AWSMP) — a collaborative effort by The NYC DEP, Ulster Co. Soil & Water Conservation District, and Cornell Cooperative Extension (CCE-UC).

Several sites were visited, including the Stony Clove Creek in downtown Phoenicia — recently devastated by massive flooding during Hurricane Irene and Tropical Storm Lee. AWSMP helped organize the Shandaken Area Flood Assessment and Remediation Initiative (SAFARI) following two similar floods in late 2010, which greatly assisted local response to last summer's infamous storm.

"There's a lot of turnover in government — we're not as trained," noted Robert A. Stanley, Shandaken town supervisor. "Generally, you just have to be a resident to run for office, and sometimes you don't have the understanding of stream morphology science behind you," he said. "I can't express enough gratitude," Stanley acknowledged of AWSMP and SAFARI, which allowed the town to provide immediate response to dangerous floods this past August.

Danny Davis, a geologist with DEP, explained that glacial sediment in the area regularly erodes from stream banks, accumulating in a manner which impedes water flow beneath bridges and culverts. Beds of dirt and gravel form in the center channels, forcing water towards the sides, accelerating stream bank degradation. A combination of dredging and computer modeled boulder weir (cross vane) can mitigate the problem, he said.

"The situation we have right now, is probably one of the most progressive proactive approaches to improving stream stewardship — in an area where people and streams are having to occupy a very limited landscape," Davis remarked, during a lengthy discussion of work performed since the last hurricane.

The boulder weir is only designed to handle ordinary seasonal floods which struck during 2010 — not 50 or 100-year flood events like Hurricane Irene. "Those [larger] floods are going to happen," Davis remarked. "[Irene] was the flood of record — it may not be next year," Davis warned.

Other sites visited included Esopus Creek along Brown Road in McKinnley Hollow, where the hurricane took out a large chunk of highway by Frost Valley YMCA. Work done to correct the stream channel will help protect homes and Co. Rt. 47. "One of our goals is to take an ongoing emergency response, and turn it into something more sustainable," said Elizabeth Higgins, AWSMP issue leader with CCE-UC. "We know we are never going to prevent flood waters from getting up here," she added, claiming future work aims to lower stream velocity.

Cory Ritz, stream project manager for the UC Soil & Water Conservation District, noted that Co. Rt. 47 only recently re-opened. "All but one of the bridges in this valley were taken out by Irene," he indicated.

Beyond local property and infrastructure protection, one of AWSMP's primary goals is keeping the water quality high and turpidity low, as part of NYC's Filtration Avoidance Determination (FAD). Unless certain thresholds are met, the NYS DEC can mandate a multi-billion filtration plant installed for the NYC water supply. All the local streams toured on Friday flow into the Esopus Creek, which in turn feeds the Ashokan Reservoir.

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