Level 1 Flood Response issued for Wanship Dam
July 2, 2011
Summit County has received notice from the United States Bureau of Reclamation and the Weber Basin Water Conservancy District that a Level One Response level has been declared for the Wanship Dam. A Level One Response is considered informational, and does not imply an immediate threat. It does, however, inform the public to prepare for possible flooding issues that may occur. The decision to declare a Level One Response is based on the likelihood that the safe channel capacity in the Weber River, below the Wanship Dam, will be greatly exceeded.
Water upstream from Rockport Reservoir has been running at approximately 2800 cubic feet per second (cfs), for the past several days. However, the Weber Basin Water Conservancy District has been able to divert several hundred cfs, permitting a lower water volume, an average inflow of approximately 2300 cfs, to flow into Rockport Reservoir.
The water flow below the Wanship Dam has been at approximately 1500 cfs for several days. This is considered the safe channel capacity for this reach of the river, resulting in high water in certain areas. With Rockport Reservoir now reaching its capacity, the Wanship Dam began spilling water down the spillway this morning. At this time, the Weber Basin Water Conservancy District is adjusting their operations to keep the total releases as low as possible.
The River Forecast Center predicts that inflow into Rockport Reservoir will remain at about 2,300 cfs for the next couple of days, and then increase to 3,000 cfs between July 3rd and 5th. Based on these forecasted increases in inflow, Weber Basin may be forced to release a higher flow of water from the Wanship Dam (an increase from 1500 to 2200 cfs), resulting in spill levels over the dam that could exceed safe channel capacity.
This increased flow would result in a significant rise in the level of the Weber River between the Rockport and Echo Reservoirs, and may result in serious flooding of properties that are within 1-2 feet above the current elevation of the river.
The forecasted cfs numbers are not exact, and may reflect peaks in flow, rather than constant flow. However, it is wise for residents to be aware of increased flow potential, and prepare for it. In the event that the water inflows increase as forecasted from 2300 to 3000 cfs, a Level Two Response may be declared, which would be a more significant threat.
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A Level Two Response would indicate a possible threat to structures, and residents and businesses within the river’s floodplain should protect their property with several rows of sand bags around the structures’ perimeter. In addition, a Level Two Response would alert residents that they should be prepared to evacuate if instructed by emergency officials to do so.
Summit County will remain in continual contact with Weber Basin Water Conservancy District and will continue to inform the public regarding any changes.