Big rains boost levels on some water starved reservoirs

Outdoors Writer

Big rains that fell across parts of the West Texas over Labor Day spoiled plenty of dove hunts. The moisture also spelled some serious relief for several reservoirs starving for water.

That’s the word from Texas Parks and Wildlife Department fisheries biologist Lynn Wright of San Angelo.

Wright said some areas reported as much as 7-10 inches of rainfall, much of it falling on watersheds that feed lakes O.H. Ivie, O.C. Fisher and JB Thomas.

O.H. Ivie was about 27 percent full capacity when the rain started; JB Thomas about 16 percent. O.C. Fisher was essentially dry.

As as of Sept. 4, the water level on ‘Thomas had jumped about 12 feet and was rising. Like O.H. Ivie was up jumped about seven feet and O.C. Fisher had risen about 15 feet.

“The rain fell in the right places,” Wright said. “Unfortunately, the ground was so dry when it started that it took about two inches just to get the creeks and rivers moving again. We got a good bump, but what we need now is another big rain. The ground is saturated really well. Anything we get would be runoff and put even more water in the lakes out there.”

Fill ‘er up

Big rises in water level following extended dry spells are a good thing. Here’s why: When water levels fall below normal and stay there for an extended period, vast areas of the lake bed normally covered by water are exposed to direct sunlight. This causes grasses, weeds, bushes, trees and other forms of terrestrial vegetation native to the landscape to sprout on shorelines, flats, tapering points and other areas that may not have seen daylight in years. The longer the lake remains low, the thicker and more widespread the new growth vegetation becomes.

When water levels rise, all the junk that grew during the low period is inundated. This displaces a sudden influx of nutrients into the water creates a jungle of underwater cover for young fish to hide in, thus leading to increased survival and recruitment while at same time creating an abundance of fresh targets for fishermen to toss their lures around.

Another benefit occurs as the newly-flooded weedbeds begin to die and decompose. This results in another big shot of nutrients into the water, which in turn benefits plankton and other microscopic plants and animals that are the foundation of the food chain.

The nutrients also act as a liquid fertilizer for the lake’s bottom, sometimes causing dormant native and non-native vegetation seed banks to spring back to life. This creates even more quality habitat where sport and forage fish populations can thrive.

Scientists call the phenomenon the “new lake effect.”