Six days left to comment on the Ashokan spillway notch
September 19, 2026
Six days remain to comment on a cut New York City wants to make in the Ashokan Reservoir spillway. The city's Department of Environmental Protection has applied to the DEC for a dam-safety permit to notch the crest of the East Basin spillway, in the Town of Marbletown, roughly 4.5 feet deep and 60 feet wide. A scour-protection blanket would go in on the reservoir side of the notch, and a row of baffles just downstream to break up the water coming through. The DEC has issued a Negative Declaration, meaning it found no significant environmental impact, and is taking public comment on the application through September 24.The notice calls the notch interim. It belongs to the Ashokan Century Program, the city's multi-year rebuild of the dam's spillway, spillway bridge, dividing weir and dikes, which DEP says is meant to give the spillways adequate hydraulic capacity while keeping the reservoir in continuous operation through construction.What the notch does is simple. A spillway crest is a fixed lip; nothing passes until the pool rises above it. Lowering a 60-foot section of that lip by 4.5 feet lets water begin passing through that section while the pool still sits 4.5 feet below the level where the rest of the crest would spill. The flow through a narrower, deeper opening runs faster, which is what the blanket and the baffles are for. In March the reservoir stood within three to four feet of the spillway crest.Everything that goes over this spillway ends up in the Lower Esopus Creek, which runs from the dam through Marbletown and Hurley, past Kingston, and into the Hudson at Saugerties. That creek has carried the reservoir's mud since 2010. Storms on the upper Esopus pick up red silt left by a glacial lake and deliver it to the reservoir's West Basin, where it is meant to settle before the water passes into the East Basin. In heavy runoff it does not settle fast enough. After Irene and Lee in 2011 the city made prolonged, heavy releases of turbid water, Ulster County threatened suit under the Clean Water Act, and the releases have run since under an Interim Release Protocol. That protocol caps spill and release together and shuts the release channel when the gauge on the Esopus at Mount Marion nears its 18-foot action stage. Hundreds of billions of gallons of turbid water have gone down the creek under this arrangement.That is the creek the finding of no significant impact was made for. Fine sediment at concentrations far below what the Esopus carries in a release year clogs the gills of mayflies, stoneflies and caddisflies, buries the ones that cannot move, and settles over fish eggs. Brown trout hunt by sight; in turbid water they feed less and swim less well. The notch adds a lower opening to a spillway whose output is already rationed against a downstream gauge. How spills through it will be counted against that combined limit over the years of construction is a fair question to put to the agency now.Comments go to Alysse Devine at DEC Region 3, (845) 256-3054 or dep.r3@dec.ny.gov, through September 24.
