Reclamation and Weber Basin Water Conservancy District Continue Work and Studies Following Seepage Detection at Arthur V. Watkins Dam
Media Contact: Barry Wirth, 801-524-3774 or 801-633-5046 (cell)
For Release: November 16, 2006
The Bureau of Reclamation and the Weber Basin Water Conservancy District are continuing 24-hour per day monitoring of the Arthur V. Watkins Dam which forms Willard Bay Reservoir north of Ogden, Utah. Additionally, intensive studies have begun to determine the cause of the seepage first detected on Saturday, November 11, 2006, along with corrective construction work.
The seepage was initially observed by a neighboring landowner on the southern section of the 14.5 mile long dam. The problem was reported to the two agencies on Monday, November 13, and initial corrective actions were completed that night. Since then, engineers have been working to discover the cause of the seepage, which eroded a portion of the dam.
Several actions are now underway. First, efforts to bring the reservoir level down are continuing. Water is being released through the outlet works into the Great Salt Lake. To speed up the process, Reclamation is now bringing pumps from its office in New Mexico to remove additional water. The pumps will be in place by the weekend. By lowering the reservoir, engineers and geologists will then be able to inspect both the face of the dam and the areas most prone to seepage.
While the entire dam is being inspected, an area 1,000 feet either side of the seepage point is being constantly monitored. While the repair of the past week is doing its job, it is critical over the long-term to insure there are no other seepage-prone areas that remain undetected or untreated.
As the reservoir is lowered, crews will also begin placing sand and gravel materials into the upstream side over the suspected seepage entrance points. The sand and gravel will blanket the seepage entrance points, thus sealing them.
In the coming weeks, Reclamation and the District will then examine the area upstream and downstream of the dam and determine if the seepage situation has been resolved and if any further repair work may be necessary. As soon as the reservoir is lowered to a sufficient point, the agencies can begin work on upstream investigation to determine where the seepage is entering the dam.
When the seepage began, about 175,000 acre-feet of water was impounded behind the 30-foot tall dam. Willard Bay Reservoir was about 80 percent full. The agencies would like to drain about 10 feet of water from the reservoir, which is about 100,000 acre-feet of water. At this time it is difficult to predict what the impact will be next year to water supplies provided by Willard Bay Reservoir.
All work at the dam is predicated upon dam safety, which is the single most important aspect of Reclamation's and the District's program. A contingency plan, if ever needed, is also in place to breach the dam into the Great Salt Lake. The likelihood of that is very remote, but nonetheless is an option if future conditions dictate the need.
The State of Utah's Division of Parks and Recreation and the Division of Wildlife Resources have been notified. While the south Marina State Park site is closed for the season, boating on the reservoir is also now prohibited as work begins. That closure will probably last about a month. The reservoir draw-down will leave enough water in place to protect the existing fishery in Willard Bay.
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