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Rain results: Streets flood, O.H. Ivie: 1.6 billion gallons and rising

Results of this week's rains in local reservoirs

SAN ANGELO, TX - The rains started September 2, 2018 and continued throughout  the week. The slow-moving clouds and soaking moisture began to saturate the area's soils, stimulating foliage growth and greening-up the landscape. Once saturating the soil, the rain began to runoff into the collection basins of local reservoirs.

September 7 saw record rainfall flood streets, making low-water crossing impassable and creating dangerous driving conditions across the Concho Valley. The San Saba river current was so swift, a dramatic helicopter rescue was necessary to lift victims to safety.

The Concho River in downtown San Angelo made for a mesmerizing view as thousands of cubic feet of water per second poured over the Irving Street low-water crossing. Video captured one truck making its way over the crossing, being pushed sideways by the powerful current, before making it to safety on the other side.

The south pool of the Twin Buttes Reservoir filled enough to cause water to flow in the equalization channel between it and the north pool. Runoff from Dove Creek (that empties into the north pool) was high enough to cause extended road closures at low water crossings.

Video scenes from the rain (click to play):

 

Here's the results of the rains by the numbers:

The chart above shows the Concho River stream flow in cubic feet per second (cfs), peaking at 2,980 cfs at 7:00 p.m. September 7, 2018. This water makes its way into the O.H. Ivie Reservoir.

This chart, captured at 6:00 a.m. Monday, September 10, shows the rate of water flowing in the Concho River at Paint Rock, on its way the to O.H. Ivie Reservoir. Any water that flowed through San Angelo will appear at this measuring station on its way to the reservoir. It peaked at 8:45 p.m. on September 8, 2018 with a rate of 1990 cfs, and is still above normal flow as O.H. Ivie continues to rise.

 

This chart from the US Geological Survey taken at 6:00 a.m. Sept. 10, 2018, shows the O.H. Ivie Reservoir continuing to rise as runoffs from its watershed collect in its basin. So far, over 5,000 acre-feet of water (over 1.6 billion gallons) has been collected and is still flowing.

Locally, San Angelo's reservoirs did see some runoff collected:

Lake Nasworthy's latest report shows it rising to 79% full and gaining 60 acre-feet of water (19.5 million gallons) this number should rise today.

Twin Buttes, south pool filled to water flowing in equalization channel to north pool. The north pool rose approximately 1.5 vertical feet.

O.C. Fisher rose about 1/2" from the rains, a change of over 400 acre-feet of water (130 million gallons).

Oak Creek Reservoir near Blackwell rose about 5' and is still rising at the time of this writing.

The E.V. Spence Reservoir is still rising at the time of this writing, and has collected approximately 488 million gallons of water (1,500 acre-feet) with a 1/2 foot vertical rise in surface elevation.

[CORRECTIONS: Dove Creek flows into the north pool of Twin Buttes, the standard abbreviation for cubic feet per second is cfs.]


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