It could be said that seasonal flooding is a way of life in Western Washington State.

Flood fighting is certainly a way of life for Seattle District.  Hit by the second flood in just two months, the district provided flood fighters to seven different river basins in Western Washington, and the Yakima River basin in Eastern Washington.  It also provided emergency flood operations for two municipal dams, and record-level flood control with Howard Hanson and Mud Mountain dams, along the Green and White rivers.

Beginning Jan. 6, an intense storm hit Seattle District’s Western Washington Region, dumping up to 20 inches of rain in 24 hours.  The rivers swelled and, even with dams and levee systems in place in many areas, flooding still occurred.  Besides two days of heavy rainfall, warmer temperatures added snow melt to the run-off and tributary stream flooding.

Although the rain stopped on Jan. 9, it was only a lull.  The weekend brought more precipitation, further taxing already saturated levees and dams.  The district deployed levee inspectors to walk the levees, especially around the Green River, for an eyes-on watch almost around the clock.

Fortunately, damage to levees was minimal.  The U.S. Army Corps of Engineers assisted the town of Orting, Wash., with repair to one of their levees, and closed up a non-federal levee per local request in Snohomish County.

The district deployed more than 60 flood fighters.  In the Olympic Peninsula the team used more than 6,000 tons of rock in a 35-hour nonstop effort to build a berm more than 1,320 feet long to help protect the Quileute Tribe property in La Push, Wash.

"The Quileute tribe was extremely happy with our work,” said Steve Horne, flood-fight team member for the Olympic Peninsula.  “Many tribal members thanked us for building the berm.”

More than 200,000 sandbags were distributed to communities, and USACE provided almost $2 million worth of assistance, including four pumps to divert water from Interstate 5 at the cities of Centralia and Fife, Wash.

Howard Hanson Dam on the Green River received peak inflows of 30,500 cubic feet per second (cfs), and USACE held outflow to zero during the flood.  Without the operation of Howard Hanson Dam, floods on the Green River at the city of Auburn, Wash., would have been greater than 72 feet.  The reservoir at the dam reached a record pool level of 1,189 feet, and it held there for nearly 48 hours.

This record-breaking effort seems to have damaged the dam, and engineers are now assessing a six foot deep, 10 foot wide depression in the dam’s right abutment.  Engineers are now making assessments and running tests to determine the level and cause of the damage.

“The damage could be caused by many things, and that's what we're investigating,” said Richard Smith, hydro-geologist with Seattle District.

Meanwhile, Mud Mountain Dam’s flood control efforts were just as impressive.  This dam sits on the White River that feeds into the Puyallup River, a valley that is home to more than 400,000 people and millions of dollars of businesses and industry.  Mud Mountain Dam reduced the flood stage in the Puyallup River by more than three feet.  Peak inflows to the dam were measured at 30,500 cfs, while it reduced outflows during the storm to zero, keeping flows in the Puyallup from reaching 70,000 cfs, which would have overwhelmed the valley with a wall of water.

Even with that, Pacific, Wash., on the White River sustained some damage.  The reservoir reached 80 percent and the forecast called for yet more rain, so releases from the dam were necessary.  Similar releases in previous storms had not flooded Pacific, but the White River had apparently shifted.  That, coupled with new sediment levels and the release flows, pushed the White River over its banks at Pacific.

“We deeply regret the flood damages in the town of Pacific,” said Col. Anthony Wright, Seattle District commander, to residents of Pacific during a town hall meeting.  “We will work with the local community and county to prevent this from happening again.”

During the storm and ensuing floods, Seattle District’s Reservoir Control Center regulated the locally-owned Upper Baker and Ross dams in the Skagit River Basin.  The Skagit River at Concrete, Wash., peaked at 62,500 cfs and the district held the outflows to minimum, reducing the flood stage downstream at Concrete by about two feet.

The district also took over operations temporarily at the Wynoochee Dam to keep flows on that river down to three feet.

(Andrea Takash contributed to this article.)