Central Oregon water managers and first responders were keeping close eyes Monday on river gauges along the Little Deschutes and Deschutes rivers, as the Little Deschutes near La Pine continued to flow at the highest levels in 17 years, raising the potential for flooding downstream in the Tumalo area.
Monday’s peak at the measuring station on the Little Deschutes actually was a little higher than on Sunday, at 1,400 cubic feet per second (cfs), said Deschutes Basin Watermaster Jeremy Giffin of the Oregon Water Resources Department.
Late Monday afternoon, the National Weather Service in Pendleton issued an urban and small stream flood advisory for Deschutes County through 3:30 p.m. Tuesday for rain and melting snow, noting minor flooding on the Little Deschutes between Sunriver and La Pine.
"There is also a concern that more flooding could occur when the water reaches the Tumalo area in the coming days due to the flatter terrain which is more prone to flooding," the advisory said.
Monday night, the NWS also issued a new wind advisory for the region from 1 p.m. to 10 p.m. Tuesday, warning of more sustained winds of 25-35 mph, gusting to 45-55 mph.
Driving through areas such as Lazy River to see the high-water impacts, Giffin said, “It’s a high flow – pretty impressive. I saw a lot of homes with water surrounding them but apparently not doing damage.” He said area residents have grown accustomed to high water at this time of year, but “this is bigger.”
The closest watch is being kept on the gauge for the main Deschutes River at Benham Falls, several miles downstream from where the Little Deschutes flows into it. So far, as of Monday afternoon, it was not showing a rise, and “all of us our scratching our heads,” Giffin said.
You can see the data at http://www.usbr.gov/pn-bin/dfcgi.pl?cfg=co_rivers -- when the Benham Falls flow, at above 800 cfs Monday afternoon, rises above 1,500, "then we start to get a little nervous," Giffin said.
“History could repeat itself,” he said. The last time there were such high flows, during flooding in early January 1997, “a couple days later, we were sandbagging all of Tumalo.”
But Giffin isn’t sure enough – yet – on the downstream impacts, and he doesn’t want to sound an alarm that doesn't pan out and be the boy who cried wolf, if it turns out the flood threat doesn’t arise as it might.
So “we’re in a holding pattern,” Giffin said, adding that there were discussions under way with irrigation districts about possibly opening some canals to relieve the downstream threat.
But that too is a balancing act, he said – not only is Giffin and other state water officials not legally allowed to operate the basin’s reservoirs for flood control, irrigation customers who are out of town, for example, could face big problems if an unscheduled rush of water comes through an open head gate, for example.
“I can’t make them turn the canals on,” he said – but discussions are taking place.
Then there are the reservoirs. Giffin said they are storing at or near maximum levels at Crescent Lake and Wickiup Reservoir.
“If I weren’t storing in the reservoirs and letting the natural flow go through, this would be many times worse,” he said.
Because Wickiup is close to capacity, Giffin said he’s likely to release more in a few days – it’s now at 39 cfs – but he’s trying to put it off until the flood threat eases.
And there’s good news in the weather forecast, in one respect: “It looks like the storms coming in are cold enough that they won’t make the situation worse, Giffin said.
Giffin was alarmed Sunday morning to see the automated Little Deschutes gauge along a private bridge off Burgess Road reading 2,000 cubic feet per second (cfs). He traveled with a fellow state Water Resources Department worker to the scene to take a manual reading and verify the actual streamflow.
Giffin said they found chunks of ice some 20 feet tall smashing into the flagged-off private bridge where the gauge sits.
“It’s shaking – ice is jammed against it,” he said.
The river, normally about 20 feet wide, was a quarter-mile wide Sunday and “looks like a lake,” Giffin told NewsChannel 21.
At that 2,000-cfs streamflow, Giffin feared “devastating” flooding, to the level of the major floods that hit much of the state in 1964.
His fears relented somewhat later, as their manual measurements found the Little Deschutes apparently had peaked at about 1,340 cfs – still the highest flow seen since flooding hit the area on Jan. 4, 1997.
The Little Deschutes is nearly 100 miles long, “so it really takes a long time for the flow to come out of the mountains,” the watermaster said, as compared to the seven or eight hours for a rain event to send higher flows from the Bend watershed down the Deschutes.
His concern is after that water enters the main Deschutes – where the summer flow through Bend is often 2,000 cfs, but farther north (downstream) “after the Riverhouse, none of that can handle it.” He noted irrigation canals are not turned on, so “the river down there can only handle about 1,300 cfs.”