Analyses of recreational water quality as related to sediment resuspension

Abstract

Aquatic sediments, at a lake beach site in the Tonto National Forest, Arizona, were experimentally disrutped to quantitatively determine the impact of sediment resuspension on recreational water quality. Sediment resuspension was found to significantly degrade the quality of recreational waters. Mean sediment fecal coliform densities exceeded mean fecal coliform densities in overlying waters by 24.7 fold. When these sediments were experimentally disrupted, fecal coliform densities and turbidity levels in the water column increased by 1.4 to 2.8 and 1.1 to 5.4 fold, respectively. The impact of sediment resuspension on overlying waters was short-lived at the point of disruption. Increasing FC densities and turbidities generally peaked within 5 sec of resuspension and declined to preresuspension levels within 500 sec. The magnitude of the resuspension impact was most significantly influenced by water depth. The greatest risk to public health was found to be within the 0.3 m depth zone; that near-shoreline area most intensively used by young children for water play.