NYC reservoir releases raise worries about stormier future

As western regions contend with drier conditions, New York City is under fire for sometimes releasing hundreds of millions of gallons of water a day from a key reservoir in the Catskill Mountains.

The occasional releases, often around storms, have been used to manage water levels in the Ashokan Reservoir and to keep the water clear. But residents downstream say the periodic surges cause ecological harm along the lower Esopus Creek. They say the high flows churn up the water so much it turns the scenic Hudson River tributary into the color of chocolate milk.

“These people can afford to offer New York City cheap, clean, beautiful water by destroying ours,” said Michael Vallarella, who lives on the creek in Saugerties. Standing on his back deck recently, he swiped through pictures on his phone of the water looking like “Willy Wonka’s chocolate factory river.”

The tensions between upstate residents and the city of 8.8 million people to the south touch on how the largest unfiltered water supply in the country will operate in an expected stormier future. Opponents pushing for changes to the water releases got a boost recently when state regulators told the city to take a deeper look at their effects.

City officials say they’re trying to strike the difficult balance of responding to downstream concerns while delivering quality water.

“If there was an easy solution to all this that could satisfy everyone’s concerns, including ours, we’d be happy to do it,” said Paul Rush, deputy commissioner for the city’s Department of Environmental Protection. “But this is a really difficult problem.”

The Ashokan Reservoir sits by rolling mountains 80 miles (130 kilometers) north of Manhattan and is the second largest of city’s 19 reservoirs. It was created more than a century ago by damming the Esopus Creek, displacing low-lying communities and seeding long-lasting local resentments over issues like watershed land-use restrictions.

The current controversy revolves around interim rules that allow large water releases — up to 600 million gallons a day — from the Ashokan through a channel that links to the lower Esopus.

Largely dormant until 2006, the channel helps regulate reservoir levels to mitigate flooding downstream, such as when big storms hit. The channel also has been used to get rid of water that is turbid — that is, cloudy with suspended particles — before it heads south to city faucets.

The city is seeking permission from the state Department of Environmental Conservation to keep making the two types of releases, along with smaller daily releases that help maintain the creek’s flow. Opponents are seeking changes.

Turbidity can be an issue with Ashokan water due to silty water flowing in. The reservoir was designed to give suspended particles time to settle in a western basin before flowing into a clearer eastern basin. But sometimes more needs to be done. The city had been using the chemical alum to reduce turbidity, but was required to limit its use in 2005.

The city says larger Ashokan releases over the past decade have all been to regulate reservoir levels, though critics say the water released after storms can be turbid just the same.

City environmental officials contend they're blamed too much for murkiness in the lower creek, saying it also flows in from other sources. The agency said in its environmental analysis they anticipated no significant adverse impacts to the lower Esopus under the releases.

Critics counter that the periodic high-volume, long-lasting releases erode banks, leave deposits and harm fish habitats on the 33-mile Hudson River tributary. Many feel the city is not being held to the same standard it applies to residents near their reservoirs.

“There’s a very different way of operating for the City of New York when it’s the watershed lands and the streams draining into the reservoir versus the downstream system,” said Amanda LaValle, deputy director of the Ulster County Planning Department.

Locals fear major releases will become more common as extreme storms increase. They point to the large storm and snow melt in December 2020 that preceded major releases over several months during which the lower Esopus often ran brown. Seven municipalities that draw drinking water from the Hudson River said those releases taxed their water filtration systems.

The pair of water releases came shortly after the city issued its environmental impact statement projecting that releases of extremely turbid water from the channel would rarely happen.

“The 2020 storm hit and it contradicted their projections,” said Mary McNamara of the Lower Esopus Watershed Partnership. “That’s why people say their climate change projections are not aggressive enough.”

State environmental regulators cited the storm in telling the city this year to perform a supplemental environmental analysis. Among other things, the city must look at the effects of the releases on the Hudson River water supplies and determine whether more climate change analysis is needed.

The city had already projected that a 5% increase in precipitation is possible by mid-century, though with far less snow. Rush, of the city environmental protection department, said the expectation of increased precipitation mixed in with dry spells “is going to be a big challenge.”

He said the city is open to adjustments in how they operate the Ashokan, noting they already have the flexibility to rely on two other upstate watersheds. The city has permission to use alum this fall when work on a tunnel under the Hudson River will require the temporary disconnection of the aqueduct for the neighboring Delaware watershed. Rush said alum use could be studied as a longer-term solution.

Some upstate officials say the releases could be modified to mix in more clear water or to increase the daily flow as a way to avoid dramatic ramp ups in water flowing down the creek. Also in the mix are engineering solutions, such as crest gates that would allow the capacity of the Ashokan's western basin.

“We’re looking for ways to really work together,” LaValle said.