The Cedar River is running at unusually high levels for this time of year as the City of Seattle opens up space in the Chester Morse Reservoir in the Cascades to store runoff from a huge mountain snowpack.

A fast and cold river means that its closure by the King County Sheriff’s Office to recreational uses last weekend will likely continue into next week.

The Green River, where a kayaker and raft went missing and were presumed drowned last weekend near Flaming Geyser State Park, also was closed by Sheriff Sue Rahr.

Seattle Public Utilities, which owns and operates the reservoir and its Masrony Dam, has been increasing the outflow in recent days to increase storage capacity.

Then, on Wednesday, Seattle ramped up those discharges that brought the flow of the Cedar River to just below a Stage 2 flood alert, according to Tom Fox, the water resources manager for Seattle Public Utilities.

However, such an increased flow will not cause flooding, although City of Renton officials expect to to have to close parts of the walkway along the river because of the higher water.

The higher release from Masonry Dam at the reservoir was to start roughly late Wednesday morning and take five to six hours. The goal was to increase the outflow by about 600 cubic feet per second, which would bring the river level in Renton to about 2,900 cubic feet per second.

The dam’s floodgate opened a 10th of an inch at a time until the outflow reached the additional 600 cubic feet per second.

The median flow for the Cedar in Renton this time of year is between 700 and 800 cubic feet per second, according to Fox.

The river rose slowly over the next 10 hours or so, peaking about 15 hours later.

But Fox said the river is being managed to avoid flooding.

“We are trying to avoid any type of situation like that,” he said.

The level of the Chester Morse Reservoir is about four feet above what’s normal for spring, Fox said. This is the time, he said, when operators want to keep the reservoir level down to accommodate the runoff later.

“This is a fairly unusual situation,” Fox said, given the time of year. The weather played a role.

The Cascades already had a “very unusual snowpack,” and then it rained before the weather turned hot and then rained afterward, he said.

Because of the big snowpack, releasing extra water now won’t affect the ability to refill later and provide water to Seattle residents and to the city’s suburban customers later this year, he said.

“We still have a lot of snow

to melt,” he said. “I don’t see a problem.”

Fox said he doesn’t know for sure how long the high water levels will persist; the weather is the big factor, he said.

According to King County, the Cedar River has not been at this level in May since 1956.

When the Sheriff’s Office lifts the ban on recreational use of the Cedar and Green rivers also depends on when the river levels drop.

As feared, last weekend’s hot weather meant a deadly day on the rivers.

A kayaker from Seattle and a rafter from Federal Way are presumed drowned in the Green River after they went missing Saturday, according to sheriff’s spokesman, Sgt. John Urquhart. The Sheriff’s Office searched until Sunday night, but was waiting to resume the search until the river lowered.

“Everyone was anticipating a death at Flaming Geyser (the state park),” said Judy Fillips of Renton, the chair of the state River Safety Council. “It’s a sad situation for some families.”

She – again – made the point about wearing a lifejacket and the importance of enforcing the law requiring lifejacket use.

“I wish they would get out there and enforce the lifejacket law,” she said.

The City of Renton has discouraged recreational use of a stretch of the Cedar River down river from the old Elliott Bridge where a massive landslide during the Nisqually earthquake in 2001 partially blocked the river.

The log jam creates hazards for river users.

“We would continue to discourage recreational use of that stretch of the river,” said Gregg Zimmerman, the city’s public works director.

Zimmerman said the city has received no reports that logs or other debris have been dislodged from the log jam and are moving toward downtown Renton.

The sheriff last closed a river on June 28, 2006 – the middle fork of the Snoqualmie River, Urquhart said.

Large orange signs are posted when a river is closed, at normal entry points, he said.

Still, there were people floating the Cedar River in front of Fillips’ house, including an inflatable raft filled with young men and their beer.

The high water level may have some impact on juvenile Chinook salmon and sockeye redds, or nests, according to Steve Foley, a biologist with the state Department of Fish and Wildlife.

The high water could push the young Chinook into salt water sooner than they’re ready and could scour out nests, he said.

Dean A. Radford can be reached at 425-255-3484, ext. 5050.