Who manages lake levels?
Lake levels in the Okanagan are managed by the Government of B.C. using a series of dams and other structures located on major lakes and the Okanagan River between Penticton and Osoyoos. The system was constructed by the federal and provincial governments in the 1950s to control flooding and (secondarily) to provide water for irrigation. A comprehensive water study in the early 1970s led to the Okanagan Basin Agreement, which recommended target lake levels and river flows to achieve several
other benefits in addition to flood control. Those recommendations formed the basis for the lake level operating plan that is still in use today.
Why does lake level management need to be improved?
It is becoming increasingly challenging to manage the level of Okanagan Lake because of the intensity and frequency of floods and droughts brought on by climate change. The worst flooding in living memory occurred in 2017, and the lake was near the lowest level in its written historical range in 2021. In addition, the dam infrastructure is reaching the end of its operational lifespan.
Improving the lake level regulation system will also provide an opportunity to reflect societal priorities and values that have changed since the 1950s. Environmental protection is much more important than it was half a century ago. While the lake level regulation system has provided significant benefits to society, its construction drastically altered the Okanagan River to a mostly straight and narrow engineered channel, significantly impacting natural river and floodplain processes. In addition, the
system was designed and constructed without consultation with or the approval of the syilx people, and its impacts on syilx society have not been thoroughly documented. Indigenous rights and title must now be considered, and Indigenous leaders and technical staff must be included as equal partners in planning processes.
What studies need to be completed to guide improvements?
A 2021 report commissioned by the OBWB and the Government of B.C. provides a road map for modernizing Okanagan lake level management and the Okanagan Lake Regulation System (OLRS). The ‘Plan of Study’ report was developed through review of historical and recent scientific and engineering work, in consultation with an advisory group of federal, Indigenous, provincial, and local governments with responsibility for Okanagan water. The report calls for 17 studies to be completed over approximately 7 years to feed information into a final plan on how to proceed in a coordinated and well-thought-out manner.
Click to expand the studies below.
> Study 1: CREATE LINKED OKANAGAN-SIMILKAMEEN HYDROLOGIC MODEL (complete)
> Study 2: IMPROVE OLRS OPERATING PLAN DOCUMENTATION
> Study 3: CREATE INTEGRATED HYDRAULIC MODEL FOR OKANAGAN MAINSTEM
> Study 4: IMPROVE LAKE INFLOW FORECASTING MODELS AND ACCOUNT FOR UNCERTAINTY
> Study 5: EXPAND GROUNDWATER KNOWLEDGE IN SUPPORT OF OLRS MANAGEMENT
> Study 6: REFINE FISH WATER MANAGEMENT TOOL INPUT DATA AND MODEL
> Study 7: REFINE MAINSTEM LAKE BATHYMETRY (complete)
> Study 8: STATE OF THE OKANAGAN MAINSTEM LAKES AND RIVER BEFORE EUROPEAN SETTLEMENT
> Study 9: OLRS HISTORY, BENEFITS, AND RETROSPECTIVE IMPACT ASSESSMENT
> Study 10: FLOOD LEVEL IMPLICATIONS OF NOT CHANGING THE OLRS OPERATING PLAN (complete)
> Study 11: OKANAGAN MAINSTEM FLOOD RISK ASSESSMENT
> Study 12: OKANAGAN MAINSTEM DROUGHT RISK ASSESSMENT
> Study 13: IMPACTS OF CLIMATE CHANGE AND OPERATING PLAN CHANGES
> Study 14: OLRS LIFECYCLE ANALYSIS AND REPLACEMENT COST ANALYSIS
> Study 15: OPPORTUNITIES TO RESTORE LOST OLRS BENEFITS
> Study 16: FEASIBILITY OF RE-NATURALIZING AND RESTORING THE MAINSTEM SYSTEM
> Study 17: GOVERNING CONDITIONS FOR MODERNIZING THE OLRS
> Study 18: DEVELOP A PLAN FOR MODERNIZING THE OLRS
These figures show past and projected lake levels at Okanagan Lake under the current regulation system (top) and a possible modified regulation system (bottom). The 2017 flood event (orange line) appears to be a rare and extreme event in the historical record. However, the event becomes continually more common into the future. According to the model, a modified regulation system can help mitigate flooding from future high lake levels.