Dale Knutsen, local weather spotter for the National Weather Service, stands by a locked gate, beyond which lies the Chester Diversion Dam. Photo by Stacy Fisher

Chester Diversion Dam diverts floodwaters from township

Directions to the dam
To visit the diversion dam, turn off Main Street onto Feather River Drive, adjacent to St. Andrews Academy, and drive 1.9 miles toward Warner Valley until you see a yellow sign nailed to a tree on the left hand side of the street shaped like an arrow with 50 W written on it.
Make a left turn onto a nondescript unpaved gravel road and continue about two-tenths of a mile until you reach the intersection; turn left and park near the locked gate. Vehicles cannot drive over the dam, but walking or biking across it is undemanding.
Photo by Stacy Fisher

Chester was officially established in 1912 and the town had been battered for decades by heavy flooding. Residents would maintain stores of food and supplies every winter in anticipation of the rainy season, hunkering down for weeks or even months, until the skies cleared and the waters finally parted.

What was needed was a way to divert the floodwaters away from downtown, but that was not to be for another 64 years.

Dale Knutsen, local weather spotter for the National Weather Service and contributor to the Chester Progressive with his monthly Precipitation Report, provided a guided tour of the Chester Diversion Dam on May 8 to highlight how critical the project was to protect Chester from flooding over the past several decades.

“Now that warm weather has melted off a lot of the nearby mountain snow, it’s once again possible to drive out to the diversion dam” to enjoy a day of recreation and sightseeing, he said.

The 40-foot high, 970-foot long earthen dam and flood control system, built in the mid 1970s near Stover Mountain, is rather unspectacular at first glance “until you realize that the dam complex protects downtown Chester from flooding without the need for gates, valves, controls or human intervention. It’s all a matter of elevation,” effectively diverting excess water into Lake Almanor, Knutsen explained.

The diversion dam was funded primarily by the federal government as part of the Chester Flood Control Channel, also known colloquially as the “Super Ditch,” which flowed robustly this winter after several substantial storms drop-kicked the drought from the region.

Before the diversion dam was constructed, Knutsen said he had heard from people living in the area tell him that downtown Chester was prone to massive flooding during the rainy season.

“The town was convinced that something needed to be done to prevent future floods,” he said.

The Chester Diversion Dam

Once visitors walk across the dam and come upon the intake structure, the clever design of the dam becomes clear.

A metal configuration shaped like a “V” features two floating cylindrical booms on tracks that move up and down with the water level to prevent debris from clogging the inlet.

Said Knutsen, “No one has to be out here to raise a gate or turn a valve; no human intervention is needed at all; it’s all automatic based on a simple design that allows water to bypass the town of Chester during the heaviest rains.”

The design of the dam allows a section to fill with water, entering the intake where it then pours into the Feather River on the opposite side of the structure, Knutsen pointed out.

Dale Knutsen points upstream across the intake structure, indicating where the Feather River approaches the dam site.

“When the amount of water arriving at the dam exceeds the desired flow capacity of the Feather River, it starts to back up behind the dam and rise.”

Shortly thereafter, “It reaches the elevation of the Chester Flood Control Channel and water begins to flow down the channel” diverting water away from town and into Lake Almanor, preventing flooding.

“When the water level declines, it no longer flows into the channel, instead it once again flows directly into the Feather River.”

There are some very pleasant spots on the east side of the dam, he noted, where people can picnic, fish for trout, take a short walk or day hike along the Feather River.

During the spring through fall seasons, there are plenty of opportunities for visitors at the dam to see geese and other bird species, as well as the occasional otter or even the rare beaver sighting downstream constructing its own diversion dam, said Knutsen.

Knutsen mentioned that Plumas County Search and Rescue, and the California Rescue Dog Association also use the area for training purposes.

There are nearby campsites a few miles farther up the road from the dam, including High Bridge, Domingo Spring and Warner Valley campgrounds.

History

Investigation of the flood situation in the town of Chester was first authorized by a resolution and adopted by the U.S. House of Representatives Committee on Public Works in June 1956, but the actual investigative work wouldn’t begin until February 1964.

A public hearing on plans for flood control was announced and published in the April 21, 1966 edition of the Chester Progressive. Representatives from the Army Corps of Engineers, including federal, state, county and municipal agencies, together with property owners set a May 11 date for discussion of the plan, which was held in Chester Memorial Hall on Gay Street.

This is a press photo from 1937 showing Main Street flooding and washed out paving from under several vehicles. Rainbow Court Lodge is on the left. Photo courtesy Chester-Lake Almanor Museum

“The town has been flooded every three to four years,” the article declared. “Plans show that a levee and channel project could economically alleviate the flood problem.”

The article went on to state that approximately 500 acres of land would be needed for all the features of the proposed project, at an estimated cost of  $1,690,000, although over the next several years dollar estimates would go as high as several million.

However, by 1974, the cost estimate for the Chester Flood Control project had settled at $2.853 million, which would include a 2-mile overflow channel, two levees and the relocation of three bridges.

Groundbreaking was planned for late June 1975, according to a June 12, 1975 article in the Chester Progressive. The winning bid went to Sacramento-based R. and D. Watson Construction, Inc.

A work crew of just 30 men were involved in the project, including carpenters from Chester, with a weekly payroll for all employees totaling $28,000.

Twenty-six large earthmoving and construction machines were utilized in the venture.

The flood control project was completed by mid-August 1976, which included the construction of a control building atop the dam structure.

Directions to the dam

To visit the diversion dam, turn off Main Street onto Feather River Drive, adjacent to St. Andrews Academy, and drive 1.9 miles toward Warner Valley until you see a yellow sign nailed to a tree on the left hand side of the street shaped like an arrow with 50 W written on it.

Make a left turn onto a nondescript unpaved gravel road and continue about two-tenths of a mile until you reach the intersection; turn left and park near the locked gate. Vehicles cannot drive over the dam, but walking or biking across it is undemanding.


Marilyn Quadrio, local historian and director of the Chester-Lake Almanor Museum, compiled this brief flood history of the town of Chester, a major problem for residents and businesses until the diversion dam and flood control system was completed in the mid 1970s.

Historically the Almanor Basin flooded every three or four years, with about one major flood per decade, after several feet of snow had fallen, followed later by a huge warm front that dropped a lot of rain, causing a major snow melt. Roads and bridges would be washed out isolating residents, which wasn’t such a problem in the early period since the winter residents expected to be isolated and had laid in food stores and supplies to last the winter.

That changed in the 1920s-30s with major population growth and increasing dependence on groceries being trucked into the area, particularly with the 1937 flood.

The new Highway 36 realignment, with a new bridge built over the Feather River extending Main Street for miles on the west side in 1936 and with brand-new asphalt paving that replaced dirt road had made local residents proud.

The massive flood of 1937 washed the new paving out of town into the pastures along the causeway, while washing huge pockets out of the highway.

After the massive flood of 1956, the U.S. Army Corps of Engineers came in and literally bulldozed a new channel for the Feather River through Chester, widening and deepening the channel.

The engineers also had a deep flood control ditch built from the river through the west side of Chester, running alongside the then Lassen Drug Store, under Main Street, along Willow Way beside Ayoob’s Hardware, the courthouse and jail out to the river on the other side of First Avenue. That ditch was proven utterly ineffective in the December 1964 flood.

The 1964 flood washed out the Main Street bridge by the Chester Theatre, and precipitated the construction of the current flood control ditch, which carries high water from the river into the lake before it reaches town.

2 thoughts on “Chester Diversion Dam diverts floodwaters from township

  • June 2, 2017 at 1:20 pm
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    Very interesting article and photos. It kind of makes one think about all the warnings and arguments about global warming. History proves this was happening long before CO2 industrial emissions were ever considered as we can see evidence of many floods in the past and how the town of Chester had to deal with the frequent damage. Keep up the good work!

  • June 2, 2017 at 11:21 pm
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    I’d say The Diversion Ditch has really been a savior for Chester. I’ve owned property right on the Feather there in Chester and moved here to fish that river going back many years as i child in the 1960’s. Without that Diversion, my land might well be stream bed by now. If not for the more regulated flows that Dam allows, a year like this year would be disastrous. It really is a Town saver, a wonderful thing!

    The only negative might be, I’ve seen it myself many times thru many years, mature fish stacked up directly below in the current release that the Dam does not divert down into the Ditch. These fish appear blocked by the Dam, can go no further upstream, and i’ve been told that they were effectively blocked by clogs of woods trash on the upstream side. If free to do as they wish, many of them would annually make the trip from Lk Almanor all the way up to the many spring Creek gravels and propagate their kind.

    So i hold that and that alone against the Dam. I feel a part of that River.

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