Benthic macroinvertebrates, periphytic diatoms, and water-quality in the West fork of the San Jacinto River, Texas.

Physiological and biological data collected in December 1979, indicated excellent water quality through most of a 28 km reach of the West Fork of the San Jacinto River near Conroe, Tx. Baseline macrobenthic diversity was low due to the relevance of sandy substrata unfavorable for colonization. However, where structurally more complex, gravel substrata occurred, macrobenthic diversity most often fell well within the range considered indicative of clean water. Periphytic diatom diversity was high at all but one station, further reflecting the general predominance of high water quality. Slight water quality degradation occurred down stream from the Conroe Regional STP, the only major wastewater treatment plant discharging directly to the reach. Suppressed biotic diversity was due to the elimination of sensitive taxa, attributed primarily to the toxic effects of residual chlorine and ammonia.