The effects on selected organisms of water passing through the Cedar Bayou Generating Station

Abstract

The quality of water passing through the Cedar Bayou Generating Station was monitored during 1976 by observing the growth and survival of fishes and crustaceans in ponds and aquaria receiving water from the discharge canal, and by maintaining fish in cages in the intake and discharge canals and the cooling lake. In addition, a regular program of sampling fishes, crustaceans, and phytoplankton in Cedar Bayou, discharge canal, and cooling lake was carried out. Mortalities among fish held in cages were generally attributable to handling stress, low winter temperatures, and gas bubble disease. Most mortalities in the aquaria were due to disease, gas bubble disease, territorial aggression, jumping out of the aquaria, and mechanical failures in the pumping system which reduced water flow to the aquaria, resulting in lethally low dissolved oxygen levels. Mortalities among pond-held shrimp were mainly due to handling, low salinities, and low winter temperatures. No significant mortalities occured among pond-held fish. Phytoplankton studies have found that mean chlorophyll a concentrations and mean primary productivity rates were higher at all sampling stations than in 1975. Concentrations of chlorophyll a and primary productivity rates were highest in lower Cedar Bayou and in Trinity Bay at the cooling lake outfall. Differences in species composition between Cedar Bayou, discharge canal, and cooling lake were disclosed by the cooling lake study. Analyses for pesticides and heavy metals of shrimp and fish held in the ponds and cages indicated that amounts of these substances were generally much less than maximum permissable levels. In general, the water passing through the Cedar Bayou Generating Station in 1976 was not detrimental to the animals used in this study.