Aquatic Ecosystems Value

The Interim Assessment Protocol for Aquatic Ecosystems in British Columbia is based on a scientific understanding of watershed processes. It is intended to provide the initial foundation for a consistent approach to province-wide watershed assessments employing standardized GIS-based methodologies and consistent data sources. 

In some regions, modifications to this protocol or alternate assessment methods have been used to generate cumulative effects assessment reports.


Watersheds are the geographic areas that channel drainage into a river or stream system. They are defined by topographic boundaries and might encompass complex natural ecosystems, highly urbanized landscapes, or elements of both. Watersheds have three distinct characteristics: (1) upland zones that intercept, infiltrate, and transport rain as groundwater and surface water flow, (2) riparian zones that border surface water bodies, filter surface water runoff, and provide shade that can lower water temperature, and (3) surface water bodies, such as rivers and lakes, that provide habitat, food, and water to aquatic and terrestrial species. Naturally functioning watersheds can also provide migratory corridors and habitat connectivity for birds and mammals. Maintaining properly functioning watersheds is an important management objective for British Columbians.

The term “watershed processes” refers to the dynamic suite of physical, chemical and biological interactions that form and maintain landscape functions on the scale of an entire watershed. Human development activities have the potential to impact the natural state of these processes by altering the timing and intensity of peak flows, accelerating surface erosion, degrading the condition of riparian zones, and/or triggering mass wasting events. Impacts can influence water quality and quantity and affect aquatic habitats.