PARENT SESSION
TP7 - Water Quality Criteria
Chair: Canton, Steve1, 1 Chadwick Ecological Consultants, Littleton, CO
2:10 PM to 5:30 PM - Tuesday, 19 November 2002
Room Ballroom A
(461) Developing Site Specific Water Quality Benchmarks using Species Sensitivity Distributions.
Ramesh, Geetha*,1, Himbeault, Kevin1, Swanson, Stella1, Digel, Mark1, Johnstone, Robin1, 1 Golder Associates Ltd., Calgary, Alberta, Canada
ABSTRACT- Species Sensitivity Distributions were used to develop site-specific water quality benchmarks for the Environmental Assessment of De Beers Canada Mining Incorporations Snap Lake Diamond Project in the Northwest Territories, Canada. Development of the species sensitivity distributions requires three primary steps which include selection of a toxicity database; statistical analysis of the toxicity data; and interpretation of the output. Following the development of the toxicity database, resident species screening was done for inclusion or exclusion based specifically on the relevance of the test species to a northern waterbody. This screening involves certain rules for using a subset of toxicological data. The statistical analysis of the data consists of development of species mean values to summarize available data for a species; determination of the cumulative probability or percent of community affected; and development of a statistical distribution to the available data set. Logistic regression models were fit to the chronic species sensitivity distributions. The resulting sigmoid curves were fit to the data that provided a model to calculate community effects from specified concentrations or potentially affected fractions (PAF) of the community were estimated. Following the development of an appropriate regression model, hazard concentrations related to 5, 10, and 20 percent effect levels were determined as site-specific water quality benchmarks.
Key words: Species , Sensitivity, Distribution, Criteria