Rains add 3.8 billion gallons to reservoirs; rivers still flowing

Water
Twin_Buttes_Reservoir

File Photo: Twin Buttes Reservoir. Photo by Ken Grimm

Recent rains, falling over a three-day period, registered multiple inches of precious water in rain gauges across the Concho Valley.

The slow-moving system produced heavy downpours in some areas, prompting occasional flooding advisories from the National Weather Service. Several low water crossings created hazardous driving conditions for motorists as rushing water poured over the streets. Several crossings were closed to traffic due to the dangers the flooding waters represented.

Local reservoirs saw increases in the water impounded in their basins as the ground became more saturated with the multi-day rains and runoffs began.

The E.V. Spence Reservoir on the Colorado River at Robert Lee has registered the most significant gain in impounded water at the time of this writing, adding 4.3K acre-feet (1.4 billion gallons) of water compared to a week ago. Runoff into its basin is still continuing; a total for this rain event will not be known for a few days as the waters make their way downhill into the reservoir.

Twin Buttes Reservoir on the Middle and South Concho rivers, along with inputs from Spring and Dove Creeks saw the second largest gain so far with 3.9K acre-feet (1.27 billion gallons) added, a 2.09%+ add to its percentage full (currently 55.98% full).

O.H. Ivie Reservoir, the main source of the city’s water supply, saw a gain of 1.2K acre-feet (391 million gallons) in impounded water, currently 63.73% full. Runoff into its basin will continue for several days as the water makes its way through the 12,000+ square miles of contributing drainage area that feeds the lake.

Other reservoirs in the area also saw gains: Nasworthy added 301 acre-feet (98 million gallons); O.C. Fisher added 104 acre-feet (33.8 million gallons); Oak Creek Reservoir added 1,789 acre-feet (582.9 million gallons).

Overall, 11,589 acre-feet (3.776 billion gallons) has been added to the total amount of water impounded by the reservoirs, and more is wending its way into the basins. It will be several days before a complete accounting of the runoff may be tallied.

More rain is in the forecast starting mid next week, please go to the weather pages of ConchoValleyHomePage.com for the latest information.

Reservoir Elevation
Sept. 5
Elevation
Sept. 12
Change
Elevation
Acre-Feet
Sept. 5
Acre-Feet
Sept. 12
Change
Acre-Feet
Gallons
Sept. 5
Gallons
Sept. 12
Change
Gallons
Percent Full
Sept. 5
Percent Full
Sept. 12
Change
Percent Full
Nasworthy 1,871.36 1,871.60 0.24 8,406 8,707 301 2,739,103,506 2,837,184,657 98,081,151 87.43% 90.56% 3.13%
O.C. Fisher 1,867.23 1,867.49 0.26 8,073 8,177 104 2,630,595,123 2,664,483,627 33,888,504 6.76% 6.85% 0.09%
Oak Creek 1,997.00 1,997.20 0.20 30,941 32,730 1,789 10,082,155,791 10,665,103,230 582,947,439 78.91% 83.47% 4.56%
Twin Buttes 1,928.16 1,928.87 0.71 100,493 104,388 3,895 32,745,744,543 34,014,934,188 1,269,189,645 53.89% 55.98% 2.09%
E.V. Spence 1,858.05 1,859.39 1.34 122,100 126,400 4,300 39,786,407,100 41,187,566,400 1,401,159,300 23.60% 24.44% 0.83%
O.H. Ivie 1,539.33 1,539.41 0.08 352,100 353,300 1,200 114,732,137,100 115,123,158,300 391,021,200 63.52% 63.73% 0.22%
Total 622,113 633,702 11,589 202,716,143,163 206,492,430,402 3,776,287,239 43.76% 44.57% 0.82%
Raw data: Area Reservoirs Week Comparison — September 5 to September 12, 2020

Notes
Comparison data source and methodology
Readings taken September 5, 2020 compared to those taken September 12, 2020 by the U.S. Geological Survey. Twin Buttes Reservoir is currently equalized, the dead pool storage of the South Pool is accounted for in the calculations of percentage full and total water impounded per the calculation directives described in “United States Department of the Interior Bureau of Reclamation Great Plains Region—San Angelo Project, Twin Buttes Reservoir, Area Capacity Tables—1964 Tables and 1970 USGS Survey, Revision 29.”

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