RP10 Aquatic Ecotoxicology
Thursday, 17 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(HUB-1117-850861) Water and sediment quality evaluation of the Santa Clara River Estuary – Analysis of impacts associated with discharge of treated wastewater.

Huber, A¹, Bailey, H², Stransky, C³, ¹ Nautilus Environmental, San Diego, CA, USA² Nautilus Environmental, San Diego, CA, USA³ Nautilus Environmental, San Diego, CA, USA

ABSTRACT- The City of San Buenaventura currently discharges a monthly average of approximately 7 mgd of tertiary treated effluent into Santa Clara River estuary. The discharge has been ongoing for approximately 45 years. The objective of this study was to evaluate whether chemicals in the effluent may be affecting water and sediment quality within the estuary. Extensive testing with a variety of both marine and freshwater species showed a low incidence and degree of toxicity, and limited exceedences of water quality criteria. The discharge generally did not appear to be associated with toxicity; causes of toxicity appeared to be localized, variable, and related to upstream sources or groundwater influence. The sediment quality evaluation indicated that contaminants of concern were generally below sediment quality guidelines, and most of the responses in the sediment toxicity tests were related to coarse substrate. Copper is a primary constituent of concern for the treatment plant based on frequent exceedence of current marine water quality criteria. However, relationships between copper and toxicity, in addition to a series of water–effect ratio (WER) studies suggest that concentrations of copper in both the WWTP discharge and estuary are below those of potential biological concern.

Key words: water quality, estuary, effluent, sediment quality