Ashokan Reservoir Interim Protocol Fact Sheet
Last year, after several storms caused significant turbidity in the Ashokan Reservoir and releases from the Reservoir had impacts on some downstream residents and the aquatic habitat, the NYS Department of Environmental Conservation and NYC Department of Environmental Protection collected stakeholder input from elected officials, environmental and community groups, and the public to develop an interim release protocol for the Ashokan Reservoir which was released in October 2011.
Public Comment & Next Steps
A formal 45-day public comment period on the Ashokan Reservoir Interim Protocol for water release management began May 23, 2012 and ended July 16, 2012. All comments received will be considered in the development of the revised Interim Protocol. Comments may be submitted by email to: Ashokan@gw.dec.state.ny.us.
A Final Protocol will be developed after a full Environmental Impact Statement (EIS) process is complete which examines all alternatives. The purpose of the Interim Protocol is to mitigate the impacts of the turbid releases from the Ashokan Release Channel to allow time for the EIS to be completed. The Final Protocol will be available for public review and comment through a State Environmental Quality Review Act process that will be conducted to modify NYCDEP's Catalum SPDES permit.
Competing Goals
The goals of the Interim Protocol are to:
- protect public water supplies;
- mitigate flooding;
- protect water quality;
- and protect aquatic habitat.
Unfortunately, steps to achieve one of the goals often have a negative impact on achieving a different goal. Therefore, the protocol attempts to achieve an appropriate balance between the multiple competing goals.
Operational Modes
The Interim Ashokan Release Protocol has three modes with specific criteria that must be met in each mode.
Community Releases: intended to provide the Lower Esopus with a supplemental base flow during normal conditions.
- Benefits: Promote habitat, agriculture and recreation
Criteria include:
- NYCDEP will release 15 million gallons per day (MGD) from the Release Channel during the summer season (May 1 to Oct. 31) and 10 MGD during the winter season.
- These rates are reduced during drought warnings and discontinued during drought emergencies when risks to public water security must be minimized.
- NYCDEP will attempt to use the layers of water with the lowest turbidity in Ashokan's West Basin.
Discharge Mitigation Releases: intended to increase the potential for the reservoir to capture stormwater during ten months of the year.
- Benefits: Capture high runoff from storms
Criteria include:
- NYCDEP will make releases to create a high probability of maintaining a reservoir void to capture high inflows and attenuate peak flood stages.
- The reservoir void target, or Conditional Seasonal Storage Objective (CSSO), will be 10 percent from Oct. 14 to Mar. 15 and zero percent from May 1 to Jun. 30 with a gradual increase and decrease between those periods. The amount of water to be released from the Release Channel will be calculated based on current storage, current snowpack, forecasted inflow and anticipated diversions.
- After the reservoir level has been reduced to the CSSO, Release Channel flow will be reduced to a level that will maintain the CSSO. If the discharge mitigation releases are highly turbid, then a three-day "flush" release will be made upon cessation of the discharge mitigation releases. This flush release will use the least turbid water available in the reservoir.
Operational Releases: intended to protect water quality in Ashokan's East Basin while minimizing downstream impacts.
- Benefits: Protect public water supply quality
Criteria include:
- NYCDEP may make releases for the purpose of promoting water quality in the diversion used for public water supply. Water would be released from the Ashokan's West Basin to reduce turbidity spilling into the East Basin, which is used for human consumption.
- The turbidity of operational releases is limited by seasonal guidelines that are designed to protect against negative effects on the downstream ecosystem.
For more information on the Interim Protocol and the draft consent order, view the Ashokan Reservoir webpage.
