Bureau still studying Red Willow Dam, lowering lake

Cracking in the embankment caused a sinkhole in a dam north of McCook, and water continues to be released from the lake behind it while officials try to decide what to do next.

"Our investigations have revealed the presence of cracking in the embankment of Red Willow Dam," said Aaron Thompson, area manager for the U.S. Bureau of Reclamation. "Because of this finding, we will continue to lower the reservoir in order to relieve stress on the structure. Reclamation's top priority continues to be the safety of the public and our facilities," he said.

"Although we are still working to fully define the issues at Red Willow Dam, it's important to share our initial findings with the public," Thompson said. "Our engineers are aware of the vital role this facility fulfills within the agricultural community and among recreationists and we ask the public to bear with us as we continue our investigations."

The recent discovery of sinkholes and embankment cracking has led Reclamation to draw down Hugh Butler Lake, which is impounded by Red Willow Dam. The target elevation is between 2,560 and 2,552 feet in elevation to allow additional investigation on the upstream face of the dam, and to assure the safety of the downstream areas. The last time the lake was at 2,560 feet in elevation was in 2002.

Experts from Reclamation recently met with managers and directors of the Frenchman-Cambridge Irrigation District to discuss future operation of the reservoir.

"Reclamation continues to move toward meeting our important role in water management, but safety is always our foremost concern," Thompson said. "The current situation will result in the loss of water supplies for the 2010 irrigation season, and will significantly impact recreation at the reservoir. We are committed to looking at all options which can help lessen impacts to the public."

Thompson said crews continue to monitor the dam, and the road across the crest will remain closed as engineers evaluate the structure and consider remedies.

"At this point, we know there is a problem with the dam which needs to be addressed. Although we do not know the full extent of the problems, the issues with the embankment will require long-term activity."

"The ultimate resolution is not going to be reached until we've adequately studied potential alternatives," Thompson said. "Reclamation is concerned about impacts to our customers and the public, and I want to express my gratitude and appreciation for the incredible cooperation we've received from folks as we move forward on this issue."

Because the activities at the dam will continue to affect users through the summer of 2010, Reclamation is issuing regular updates at http://www.usbr.gov/gp/nkao/redwillow/ to keep the public informed. Individuals cal also use the site to ask questions and sign up to receive any future mailings.

Red Willow Dam, located on Red Willow Creek about 11 miles north of McCook, is an earthfill embankment with a structural height of 126 feet, which forms a reservoir of 85,070 acre-feet. An ungated concrete spillway is located in the right abutment. An outlet works through the base of the dam provides for river and irrigation releases for downstream diversions. The reservoir behind this dam is Hugh Butler Lake.