Osoyoos Lake Summer Conditions Update
Photo: Town of Osoyoos Boat Launch June 16, 2026. Credit: Tyler Madsen.
The International Osoyoos Lake Board of Control (the Board) is providing an update on current lake levels and ongoing drought-related water-management actions for Osoyoos Lake. The Washington State Department of Ecology (Dept. of Ecology) operates Zosel Dam and manages lake levels within the ranges established under the International Joint Commission (IJC) Orders of Approval. The Board oversees the Dept. of Ecology’s compliance with the Orders.
Current Lake Levels and Operations
For the last few weeks, Osoyoos Lake levels have been held just below 912.5 feet, which is the upper limit of the allowed summer range during drought conditions. Levels have now begun to gradually decline. This decrease is expected to continue as the Dept. of Ecology works to balance multiple needs: maintaining instream flows to meet water rights obligations and support fish, and storing water in the lake for later in the season.
The Dept. of Ecology continues to operate under the drought rule curve (red dashed line in Figure 1) outlined in the IJC’s 2013 Supplementary Order of Approval, which provides additional flexibility for managing the lake during dry years.
Lakeshore residents and recreationists should expect lake levels to keep dropping and plan accordingly. Real-time lake level information is available on the USGS Osoyoos Lake water data page.
The Board will continue to track Osoyoos Lake and Okanagan River conditions and provide updates as conditions change over the summer.
Figure 1: Water year 2026 (bright green) and water year 2025 (dark green) Osoyoos Lake Levels, along with allowable range under the normal rule curve defined by the International Joint Commission Orders of Approval for Osoyoos Lake (solid black). Expanded drought Conditions rule curve (red dashed). For the period of record from 1987-2025, the mean daily lake level is shown as a black line, and the historical gauged minimum, 10th, 25th, 75th, 90th, and historical gauged maximum lake levels are shaded grey (USGS, IOLBC 2026).
Short Exceedance of the 912.5-Foot Limit
On May 29, lake levels briefly exceeded the 912.5‑foot limit due to an unforeseen combination of strong northerly winds, which pushed water toward the south end of the lake, and heavy rainfall, which temporarily increased inflows.
The Dept. of Ecology quickly increased releases through Zosel Dam, bringing lake levels back within the allowable range. Operators will continue monitoring conditions closely to help prevent further exceedances.
Regional Drought Conditions
The Okanagan/Okanogan region continues to experience drought:
British Columbia has designated the Okanagan Basin at Drought Level 3.
Washington State remains under a statewide drought declaration, and the U.S. Drought Monitor listing the Okanogan Basin at D1- Moderate Drought.
Local, regional, and Indigenous governments across the basin have enacted additional drought declarations to manage water supplies and reduce community impacts.
These conditions underscore the importance of proactive, collaborative binational water management.
Quick Facts
The International Osoyoos Lake Board of Control oversees the operation of Zosel Dam to manage water levels in Osoyoos Lake, which crosses the British Columbia-Washington border.
Annual public board meetings alternate each year between Osoyoos, B.C., and Oroville, WA. The next meeting will be held September 23, 2026, at 6:30-8:00 PM in Oroville, WA. Watch for future News Releases for more information.
To learn more about the board, visit its “Frequently Asked Questions” page.
Stay in touch and subscribe to receive email news updates from the Osoyoos board.
Contacts
Sarah Dunn, U.S. Secretary
Martin Suchy, Canadian Secretary
To contact the board by email, use the Contact form on the board’s website.
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