Arkansas River basin dam report

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Repairing dams that have been restricted by the State Engineer’s office and/or dredging silted in reservoirs could provide storage for Colorado at a low cost. Here’s a report from Chris Woodka writing for The Pueblo Chieftain. From the article:

As state engineer, [Jeris] Danielson battled with lawmakers over funding for inspectors. The catastrophic failure of the Teton Dam in 1976 renewed interest in the safety of dams program, which has been a responsibility of the state engineer for more than a century. Now, some of the dams that have been restricted over the years might be brought back to life. In fact, there are efforts to revive the two largest restricted reservoirs in the Arkansas River basin.

The Two Rivers Water Co. — Barber is president of the company — is trying to bring back Cucharas Reservoir in Huerfano County by building a new dam downstream of a dam that breached in 1987. The dam, on the Cucharas River in Huerfano County, has a capacity of more than 40,000 acre-feet, more water than Pueblo water customers use in a year. But filling it is problematic because there is rarely enough water in the river at the right time of year. Constructed in the early 1900s, the reservoir was used to irrigate Pueblo County farmland. Two Rivers’ stated goal is to bring at least some of that land back into production. The original dam is restricted to about 7,500 acre-feet of storage because of poor overall construction and movement along the embankment. The new owners intend to construct a new dam downstream to overcome the problem. The cost could reach $30 million — about $1,000 an acre-foot for recovered storage.

The Two Buttes Reservoir straddles the Prowers-Baca county line on Two Buttes Creek, and once had a capacity of 41,000 acre-feet. It is restricted to less than 10,000 acre-feet by dam safety issues, and like Cucharas rarely has water available to fill it. The Division of Wildlife, which has a wildlife area at the Two Buttes site, has been working to remove restrictions on the dam. Plans are not far enough along to estimate costs.

Those two sites, with restrictions totalling more than 64,000 acre-feet, make up 83 percent of the storage lost to restrictions in the Arkansas River basin, said Mark Perry, dam safety engineer for the Division of Water Resources. Overall, there are 44 reservoirs, out of 310 in the Arkansas River basin, that have restrictions. Most amount to a few hundred acre-feet of lost storage each. In total, about 77,500 acre-feet have been lost to restrictions…

Far more common is the unavailability of water at the right time in the right place. In theory, there is massive storage available in the Great Plains Reservoirs, between Eads and Lamar. Fed by ditch canals, five reservoirs in the system could hold 265,000 acre-feet. But, as a presentation by CDM Engineering at last week’s roundtable meeting pointed out, the lakes have been dwindling for the past 10 years because the junior water rights they live on are not in priority…

Lake Henry and Lake Meredith in Crowley County are used by Colorado Springs, Aurora and ditch companies in the winter water program, so maintain higher levels. The cities use the storage to exchange water upstream. The Holbrook Canal stores water in its lakes, under contract, to allow cities to recover water that has been bypassed under a 2004 agreement to maintain flows through Pueblo.

Reservoirs also fill quickly with sediment downstream from Pueblo. Blue Lake, a Fort Lyon Canal reservoir north of Las Animas on Adobe Creek, once was 30 feet deep in places, but now is just 12 feet deep. Crews were able to dig out about 4 feet of sediment before it began to refill again in 2005 after four years of drought. In 2008-09, the Army Corps of Engineers hydraulically dredged John Martin Reservoir to break through 50 years of accumulated sediment — roughly 90,000 cubic yards. In some places, the sediment was 20 to 25 feet deep.

More Arkansas River basin coverage here.

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