Before-and-after studies on the effects of a power-plant installation on Lake Lyndon B. Johnson: before studies. Volume I. Monitoring data. Final report to the Lower Colorado River Authority

Technical Report · Sun Dec 01 04:00:00 EST 1974

OSTI ID:6378987

Fruh, E G; Maguire, B Jr; Schmidt, P S

The goal was to determine if the proposed LCRA power plant operations have any significant effect, beneficial or detrimental, on the Lake LBJ ecosystem. Data were collected from 1971 through 1973 before power plant operations began. The trends in the 1971 through 1973 data indicate that Lake LBJ is essentially functioning as a new reservoir after the drawn-down and refilling operations from October 1970 through May 1971. During the three year periods floods caused marked changes in water quality and biological populations. Lake LBJ is a short detention time reservoir with thermal stratification from late February through October. Dissolved oxygen becomes depleted during the summer in the hypolimnion. Nutrient loadings to Lake LBJ are quite high. The phytoplankton consist of diverse green algae through the year with a consistent dominance of non-nuisance blue-green algae in summer and early fall. The dominant zooplankton are the rotifers. Benthic productivity is exceptionally high but only in the old flooded river channels. Despite the rotenone and fish stocking operations, rough fish rapidly dominated this impoundment. The trends indicate that no significant detrimental effect occurred to the Lake LBJ ecosystem due to LCRA's reservoir lowering and refilling operations. Because of the large scale variations in river flows and associated water quality and nutrients, the power plant is not expected to exert a significant detrimental effect on the ecosystem of Lake LBJ. The temperature plume also is not expected to have a significant detrimental direct effect on the ecosystem of Lake LBJ on the water quality and biological populations in the discharge cove. However, an indirect effect may occur if the relatively shallow discharge cove has a stable thermal stratification for a long period of time.

• Research Organization: Texas Univ., Austin (USA). Center for Research in Water Resources
• OSTI ID: 6378987
• Report Number(s): CRWR-123; EHE-75-04; ON: DE83901596
• Country of Publication: United States
• Language: English

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ALGAE
ANIMALS
AQUATIC ORGANISMS
BASELINE ECOLOGY
BENTHOS
DISASTERS
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