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USDA-NRCS Watershed Rehabilitation Program in New York State

Typical vegetated earthen auxiliary spillway that should be designed to not breach in a Probable Maximum Precipitation (PMP) event. Click image for full screen view
Typical vegetated earthen auxiliary spillway that should be designed to not breach in a Probable Maximum Precipitation (30 inches in 24 hours) event. Full screen view
Erosion on an auxiliary spillway that occurred after a 500 year event (14 inches in 24 hours). Auxiliary spillways should not breach during a Probable Maximum Precipitation (30 inches in 24 hours) event according to NRCS criteria for high hazard dams in TR-60. Click image for full screen view
Examples of erosion on an auxiliary spillway that occurred after a 500 year event (14 inches in 24 hours during Hurricane Irene). Auxiliary spillways should not breach during a Probable Maximum Precipitation (30 inches in 24 hours) event according to NRCS criteria for high hazard dams in TR-60. Full screen view
Erosion on an auxiliary spillway that occurred after a 500 year event (14 inches in 24 hours during Hurricane Irene). Auxiliary spillways should not breach during a Probable Maximum Precipitation (30 inches in 24 hours) event according to NRCS criteria for high hazard dams in TR-60. Click image for full screen view
Full screen view
Erosion on an auxiliary spillway that occurred after an 500 year event (14 inches in 24 hours during Hurricane Irene). Auxiliary spillways should not breach during a Probable Maximum Precipitation (30 inches in 24 hours) event according to NRCS criteria for high hazard dams in TR-60. Click image for full screen view
Full screen view

Local communities in New York State, with NRCS assistance, have constructed 59 flood control dams since 1955. A few of these dams are nearing the end of their 50-year design life. Other dams are now considered high hazard (1) due to the development that has occurred downstream although they were built to only significant hazard criteria originally. In addition, updated criteria for the design and functioning of auxiliary spillways to prevent an erosive breach during an extreme flood event up to a Probable Maximum Precipitation (PMP) (2) have been applied to these dams. Rehabilitation of these dams is needed to address critical public health and safety issues in these communities. The following information provides background and case studies of rehabilitation needs of NRCS watershed dams in New York State as well as progress toward rehabilitation accomplishments.

(1) Low Hazard Class are dams located in rural or agricultural areas where failure may damage farm buildings, agricultural land, or township and country roads.

Significant Hazard Class are dams located in predominantly rural or agricultural areas where failure may damage isolated homes, main highways or minor railroads, or cause interruption of use or service of relatively important public utilities.

High Hazard Class are dams located where failure may cause loss of life, serious damage to homes, industrial and commercial buildings, important public utilities, main highways, or railroads. (Source: Earth Dams and Reservoirs, TR-60)

(2) Probable Maximum Precipitation (PMP) theoretically is the greatest depth of precipitation for a given duration that is physically possible over a given size storm area at a particular geographical location at a certain time of the year (Source: Hydrometeorological Report - 52).

2014 Watershed Rehabilitation Update

The 2014 Farm Bill made about $262 million available for rehabilitation of 151 dams in 26 states. These watershed management projects provide an estimated $2.2 billion in annual benefits in reduced flooding and erosion damages, recreation, water supplies and wildlife habitat for roughly 47 million people. Projects were identified based on recent rehabilitation investments and the risks to life and property if a dam failure occurred. New York State NRCS and New York dam sponsors received $2,900,000 to do assessments on 19 dams as well as to complete the planning on 10 dams that have been identified as potentially needing rehabilitation.

Specific information on the Watershed Rehabilitation Program projects in New York State will be announced here as it becomes available.