Planned water releases from a flood-control dam in the upper Green River watershed will lead to increased flows downstream – including some minor flooding in the middle reach of the Green above Auburn Sunday evening. As of Sunday afternoon, the Tolt River had reached a Phase IV flood alert level, with major flooding possible in the Carnation area.
The King County Flood Warning Center, which has been monitoring river flows since 2 a.m. Sunday, has issued a Phase II flood alert level for the Green River, which is expected to be flowing at 7,000 cubic feet per second (CFS) at Auburn by 10 p.m. Sunday.
The targeted 7,000 CFS flow is a combination of planned releases from Howard Hanson Dam, plus the natural inflow from streams that empty into the Green River between the dam and the City of Auburn.
At this flow, very minor flooding could be expected in the largely rural and sparsely populated agricultural area of the Green River Valley upstream of Auburn. No river flooding is expected farther downstream, including in the cities of Auburn, Kent, Renton or Tukwila.