06-20-19 NRCS-CO: Flooding Averted as Watershed Dams are Called into Action

NRCS-CO: Flooding Averted as Watershed Dams are Called into Action

DENVER, CO, June 20, 2019 – On May 28, 2019 heavy rain and hail hit Colorado’s Northeastern Plains, wreaking havoc on agricultural crops and livestock. However, the impact could have been much worse. Flooding could have been a part of that mix. Thanks to nine dams installed by the US Department of Agriculture’s (USDA) Natural Resources Conservation Service (NRCS), the areas below these watershed dams were protected from flooding. These inconspicuous earthen structures protect people, livestock, rangeland and cropland. They also safeguard several irrigation ditches, county roads, bridges and buildings from being damaged by flash floods after large rainfall events.

The Sedgwick Sand Draws Watershed Dams are in the draws or valleys that feed the South Platte River as it is exiting Colorado and entering Nebraska. The dams are a few miles north of I-76 in Sedgwick County, Colorado’s northeastern most county. They cannot be seen from the highway, yet they serve as silent protectors of life, land and other infrastructure in northeastern Colorado and western Nebraska. Each of the watersheds extend an average of four miles into Nebraska. The watersheds behind each earthen structure range in size from 12-square miles to just under 1-square mile.
Before these structures were built, runoff from a rainfall event would quickly reach the South Platte River. If several of the watersheds received a significant amount of rain, the runoff from each watershed would reach the river at about the same time, causing the water level in the river to rise abruptly. Today, these earthen structures temporarily detain the water in the upstream basin directly behind each dam.

An inlet structure and pipe in each basin controls the flow into the main drainageway, ensuring that any runoff from the watershed reaches the South Platte gradually. This reduces the potential for flooding along the South Platte River as well as the areas below each dam.

The dams were planned and designed in a joint agreement with local sponsors by the USDA – Natural Resources Conservation Service (NRCS), formerly the Soil Conservation Service (SCS). Construction on the first dam started around 1979 and the last was installed in 1991. SCS planned, designed and oversaw the construction of the dams which remain dry until a storm hits.

Over the years, NRCS has installed over 150 of these dams across the state yet some 80% are in the northeastern portion of the state. The dams were built throughout US Public Law 566. This federally funded watershed protection program is was made possible by Congress in 1953 and is managed and administered by the NRCS. It allowed small communities to garner federal assistance to protect their communities from devastating floods. Eventually the operation and maintenance of the dams was turned over to local sponsors. Today these sponsors, along with local NRCS staff inspect and perform maintenance on these structures. Although they generally do not require a lot of maintenance, some annual upkeep is required because maintenance and care are critical to preserving their integrity.

For more information about the PL-566 program or any program managed and administer by the NRCS, please visit www.co.nrcs.usda.gov. For more information about how you can help ensure these dams continue to guard and protect communities from flooding, please contact the Sedgwick Conservation District at 970-474-3684.

NRCS…Helping People Help the Land.

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