Using Watershed Ecological Risk Assessment for Protecting Drinking Water

Objective/Intended Use

This effort describes how watershed ERA can be applied to protecting drinking water through watershed and reservoir management.

Abstract

The first manuscript describes the application of watershed ERA principles to the development of a strategic watershed management plan for Victoria, British Columbia, Canada, where the primary focus was on the protection of drinking water quality, a concern typically addressed by human health risk assessors. The approach emphasizes adaptations to the problem formulation phase of ERA (defining assessment endpoints, developing conceptual models and an analysis plan) suitable for watershed management planning in a multi-objective, multi-stressor context. Physical, chemical and biological attributes were selected for primary drinking water quality assessment endpoints, and coupled with additional assessment endpoints relevant to other environmental and social management objectives. Conceptual models helped the planning team to better understand and communicate the myriad of natural and human stressors in the watershed and the causal pathways by which they affected drinking water. The paper provides an example of the types of adaptations that can make ERA principles more suitable to watershed management, and illustrates the efficiency of integrating health and ecological assessments. The second paper presents an example of the integration of ecological risk assessment with decision analysis in the development of a watershed management plan for the Greater Vancouver Water District in British Columbia, Canada. Assessment endpoints were developed, ecological inventory data were collected, and watershed models were developed to characterize the existing and future condition of three watersheds in terms of the potential risks to water quality. Stressors to water quality include sedimentation processes (landslides, streambank erosion) and forest disturbance (wildfire, major insect or disease outbreak). Three landscape-level risk management alternatives were developed to reflect different degrees of management intervention. Each alternative was evaluated under different scenarios and analyzed by explicitly examining value-based trade-offs among water quality, environmental, financial and social endpoints. The objective of this paper is to demonstrate how the integration of ecological risk assessment and decision analysis approaches can support decision makers in watershed management.

Project Status

Project funded. Work is on hold pending completion of other projects.

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