Public Information Statement
National Weather Service Seattle WA
945 AM PDT Fri Nov 1 2019

...Notification regarding a change in the Flood Warning levels for
the White River...

The National Weather Service has adjusted the flood warning levels
for the river forecast points on the White River, effective today,
November 1, 2019. The flood warning level, called flood flow or
flood stage, is the river level at which a flood warning is issued
by the National Weather Service to warn of flooding impacts.

Flood mitigation efforts by local agencies have improved the
carrying capacity of the lower White River such that flood impacts
for the White River at R St. Bridge gage (WRAW1) in the vicinity of
the cities of Auburn, Pacific, and Sumner are no longer an issue at
the current flood flow of 5,500 CFS. High river flows in recent
years reached 7000 CFS multiple times without causing flooding. In
addition, LIDAR of the channel and subsequent flood inundation
modeling supports a higher flood level.  For the river forecast
point White River Outflow from Mud Mountain Dam (MMRW1), the flood
flow was 10,000 CFS back in 2009. When flooding first started to
occur around the City of Pacific with river flows below 8,000 CFS,
the MMRW1 flood level was lowered 8,000 CFS to account for that.
Once the river forecast point at R St. Bridge was established to
specifically cover the lower White River, the artificially low flood
level for MMRW1 was no longer needed.  The following new flood
levels on the White River have been coordinated with the Emergency
Management Divisions and Public Works Departments of Pierce and King
Counties, and the above cities.

The moderate and major flood flows remain the same at both locations
at this time.

Here are the new and old flood flows:

River Gage               New Flow       Old Flow

White River at R Street
Flood Flow/Minor Flood   6,500 CFS      5,500 CFS

White River below Mud Mountain Dam
Flood Flow/Minor Flood   9,000 CFS      8,000 CFS

If you would like more information about the National Weather
Service hydrologic services in the Seattle area, please contact
Brent Bower, Senior Service Hydrologist, at 206-526-6095.