Work began in late July on a $1 million restoration of Broadstreet Hollow, a Catskills stream that feeds New York City’s water supply, in an effort to slow erosion, reduce the fine sediment that clouds the water downstream and improve habitat for fish and other aquatic life.
The project covers about 1,300 linear feet of channel and roughly five acres of stream and floodplain.
Broadstreet Hollow flows into the upper Esopus Creek near Allaben in the Town of Shandaken and drains to the Ashokan Reservoir, which supplies about 40 percent of the daily drinking water for more than 9 million people in New York City and communities north of it. The Ashokan Watershed Stream Management Program (AWSMP) is realigning and resizing the stream to move it away from a landslide on the valley wall and to limit erosion into adjacent private property.
The work is one of a series of stream restoration projects undertaken by AWSMP, a partnership of Cornell Cooperative Extension of Ulster County, the Ulster County Soil and Water Conservation District and the New York City Department of Environmental Protection.
“These projects don’t only benefit New York City but they also benefit the communities in which they’re built from flood protection, stream stability, to providing aquatic habitat for the ecotourism of the Catskills,” said Bobby Taylor, the Ashokan basin coordinator for the Catskill Streams Buffer Initiative at the Ulster County Soil and Water Conservation District.
AWSMP flagged the site in 2001 for chronic erosion, channel instability and exposure of fine clay soils, a common source of sediment in the watershed. The program identifies the location as one of the larger producers of suspended sediment it has documented.
Unstable banks release sediment into streams, producing turbidity, which the DEP identifies as the primary water quality concern in the Ashokan Reservoir. High turbidity can also degrade aquatic habitat.
The site includes private property, and Taylor said sustained communication with landowners is central to the work.
Much of the $1 million construction cost covers diverting the stream through a pipe to create a dry work area, along with equipment used on site. As the channel is drained, crews move trout and other fish out by net and five-gallon bucket — a task Taylor described as “all hands on deck.”
“Overall the system benefits from these restoration projects,” said Leslie Zucker, AWSMP program manager at Cornell Cooperative Extension of Ulster County, “often by reconnecting the channel with its floodplain and creating access to habitat upstream and downstream so both we and the NYSDEC, that permits the projects, agree they should have a net benefit.”
Funding comes from the DEP and is tied to the Filtration Avoidance Determination, the New York State Department of Health order that allows the city to deliver unfiltered water from its Catskill and Delaware supplies rather than build a filtration plant.
“We’re trying to protect the water at the source here in the Catskills,” Taylor said.
The design, by the ecological restoration firm Ecosystem Planning and Restoration, follows the natural channel design framework developed by hydrologist Dave Rosgen, which uses stable reference streams as a template.
The approach relies on natural materials, including wood cut on site and reused to build access points. Rock will be buried beneath the stream channel and topped with existing cobble. Large boulders will be placed throughout the site to create habitat.
Nearby floodplains will be regraded and reconstructed to give the stream more room during floods and allow water to spread laterally across the valley floor. According to AWSMP, flood elevations will not rise, though the area of inundation will expand.
Planting is scheduled from October through the second week of November. Willows, dogwoods and alder will go in closest to the stream, with maples, oaks and sycamores farther out in the floodplain. Remaining disturbed soil will be seeded with native grass and wildflower mixes.
AWSMP also runs a separate program for streamside landowners that uses native plantings to reinforce stream banks.
Through a partnership with the U.S. Geological Survey, AWSMP is conducting three years of monitoring before and after construction to track effects on aquatic life, along with monitoring at a control site for comparison.
“During the development of a stream project we look closely at healthy and stable stream conditions found near the project site to learn about features that create good habitat for fish and other organisms,” Zucker said, “such as pools and their depth, riffles and their spacing, channel geometry and the types of native vegetation near streams.”
AWSMP aims to complete one large-scale restoration project each year. Next summer, the program plans to work at the top of the Stony Clove Creek watershed along Hollow Tree Road.
The contractor, Kinsley, expects to finish in-stream construction by Sept. 30.
Mia Quick is an editorial assistant at The Overlook. Send correspondence to mia@theoverlooknews.com.
