Current Water Supply Conditions and Outlook
September 17, 2014
Our overall water supply situation and outlook is good.
Last week, 0.43 inches and 0.23 inches of precipitation were recorded in our Cedar and South Fork Tolt River watersheds, respectively.
Chester Morse Lake at the Overflow Dike is at elevation 1553.3 feet, about 0.9 feet lower than last week, and about 4.0 feet above its long term average (based on the years 1989 to 2005). Masonry Pool Reservoir at Masonry Dam is at elevation 1552.9 feet, about 0.9 feet lower than last week, and about 14.2 feet above its long term average. The South Fork Tolt Reservoir at the South Fork Tolt Dam is at elevation 1738.6 feet, about 2.2 feet lower than last week, and about 5.0 feet below its long term average. Water releases from reservoir storage are actively being managed for water supply and fish habitat management objectives for both the Cedar and South Fork Tolt Rivers.
Water consumption for the previous seven days averaged approximately 145 mgd. That is more than the 138 mgd consumed during the same period last year, and less than the average of 161 mgd used during the same period over the years 1999-2008.
This year’s migration of adult sockeye salmon through the Ballard Locks facilities is drawing to a close. The total count of upstream migrating sockeye this year is well below the preseason forecast. After passing through the ship canal, these fish move into the deep, cool waters of Lake Washington where they undergo final maturation prior to migrating into the Cedar River and other areas to spawn during the fall. Significant numbers of sockeye typically start to enter the Cedar River in early to mid-September. Most of these fish spawn from mid-September through mid-December.
Adult Chinook salmon are also moving upstream at the Locks. So far this year, counts are running well below the 10-year average counts. Adult Chinook migration at the locks increases during August, with peak counts usually recorded during the second half of the month. Chinook typically begin to move into the Cedar River in significant numbers by mid-September. Chinook spawning usually peaks in early to mid-October and continues through mid-November.
Adult summer-run steelhead are returning to the Tolt River basin. Most of these fish will move into the upper reaches of the South Fork Tolt where they hold through the summer and fall, then spawn during the following winter and spring.
View Current Water Supply Graphs (pdf)