USGS team charts Yakima River flow (w/ gallery)

BENTON CITY -- Disregarding the "Boat Ramp Closed" sign, three men backed a truck into a parking lot in Benton City that was covered with a foot of water to launch a 16-foot aluminum jet boat into the churning Yakima River.

Armed with Doppler radar instead of steelhead rigging, the members of the U.S. Geological Survey planned to cruise the roiling rapids Thursday morning to measure how much water was coming down the flooding river.

Kevin Wright, supervisory hydrologic technician for the Kennewick field office, said the radar system hanging over the bow and into the water could measure water volume, depth, width and velocity, giving a flow rate in cubic feet per second.

"We measure six to eight times a year, and at major events," Wright said.

Thursday morning qualified as a major event, with the river running almost a foot over flood stage.

Thursday's measurements showed more than 20,000 cfs flowing at midday, but that was down from the night before, when the river flow peaked at approximately 22,000 cfs, as recorded by the Kiona stream gauge at Benton City.

Evidence of high water marks from Wednesday night showed the river had retreated more than 18 inches from its high point within 12 hours.

But the river still had plenty of hydraulic muscle to flex.

Thursday's float was more of a fight, with the boat having to battle upstream against a river moving an estimated 11 or 12 feet per second.

But the jet boat's rooster tail stood up against the Yakima as Dewey Copeland and Gabe Landrum piloted the Sea Ark more than a mile upstream past the Highway 225 bridge at Benton City.

Wright said that taking Doppler readings not only helps confirm gauge station measurements, but also aids in providing information useful for meteorologists in issuing flood warnings. It also can provide reliable whitewater rafting conditions and useful data for fishing conditions.

"The public uses our information a lot," he said.

Once in position, Copeland and Landrum lowered the Doppler bubble into the river, carefully keeping the bow aimed upstream as they slowly traversed the river from one side to the other and back.

Each pass provided radar readings that were relayed back to a ground-based unit.

Thursday's excursion was the latest in a half-dozen trips the Kennewick U.S. Geological Survey team has done in the past week, Wright said. They also took measurements on Mill Creek in Walla Walla County, on the Umatilla River in Oregon, and on the Klickitat, Yakima and parts of the John Day rivers.

Wright said his office tracks water flows at 49 stations across the state.

Thursday's high volume was notable, Wright said, because the highest peak flow recorded last year was 7,500 cfs. The lowest on record was 105 cfs in 1906, while the record peak was in 1933 with 67,000 cfs, Wright said.

The high flows this week are because of rain and melting snow caused by warm temperatures at high elevations.

By 5 p.m. Thursday, the gauge at Benton City was reporting a flow rate of 17,900 cfs, which was down about 10 percent from midday.