Determination of Instream Flow Needs for the Okanagan Basin
Okanagan Basin Water Board
The Okanagan Basin Water Board (OBWB), along with the Province of British Columbia, First Nations and other Federal and Provincial agencies, is currently undertaking an Okanagan Basin Water Supply and Demand Study (OBWSDP). The goal of this project is to update work completed in the 1960s and provide a best estimate of present and future water use and availability in the Okanagan Basin, taking into account population growth, climate change, land use change, environmental requirements, and other factors. The focus is on developing a credible scientific water budget to quantify future water availability and demands in the basin. Water balance information is the critical input to any rationale water policy decision-making process, including water licensing meant to support future economic, ecological, and domestic needs.
In addition to conducting a User Needs Assessment and developing the project’s overarching data management platform (Okanagan Water Database), ESSA was contracted to determine baseline ecological instream flow needs (i.e., ecological demand) throughout the Okanagan Basin, given the absence of detailed stream-by-stream studies. Typically, instream flow requirements are one of, if not the most significant components in any water budget. This information will be used to inform questions around surplus water availability and risks for responsible allocation in a scientifically defensible manner.
ESSA’s specific project tasks were:
- completion of a comprehensive review of all previous methods used for evaluating instream flow requirements for the Okanagan Basin;
- development of practical methodologies based on naturalized streamflows for determining instream flow requirements for fish and other key indicator species in Okanagan streams;
- estimation of weekly instream flow needs for stream nodes identified for the Okanagan Basin;
- acknowledge different risk levels embedded in the instream flow guidelines; and
- upload of data and related metadata from this study to the OkWater Database.