Big Bear Dam not at risk

Big Bear Dam

Municipal Water District officials are not concerned about an event similar to Oroville happening in Big Bear.   Below is an article from Natalie Williams of the Big Bear Grizzly.

Big Bear Dam not at risk

Unlike the damage, flooding and evacuations at the Oroville Dam in Northern California, the dam on Big Bear Lake is in good shape.

“As far as dam safety and issues and concerns of flooding, we’re about half capacity right now, so we have a long ways to go, ” said Mike Stephenson, general manager of the Big Bear Municipal Water District.  As of February 1`, the dam was 13 feet, 4 inches from full.

Stephenson said the Big Bear Lake dam is not at risk of experiencing issues similar to the Oroville Dam in Northern California.  The problems with Oroville Dam began February 7 after a large hole emerged in a spillway after the region experienced heavy rains.  Evacuations for at least 188,000 followed February 12 after there were concerns of the spillway failing, according to The Mercury News.

The Big Bear dam can withstand an 8.3-plus earthquake and 3 feet of water over the top, Stephenson said.

When water is released from the Big Bear dam, it takes nine hours to travel from the Big Bear dam to the Seven Oaks dam.  “Seven Oaks is double the capacity of Big Bear and can never be more than half full, so it can take the entire Big Bear Lake and hold it behind it,” Stephenson said.  If there were a breach, Seven Oaks would be able to successfully capture the water.  There are a few campgrounds near the path of the water, which are unoccupied during the winter months, so Stephenson said there’s really no risk or danger.

“Our capabilities for release are incredible,” Stephenson said.  “And if we got into a situation where we saw an impending storm, and we’re a foot or two from full, we certainly would start a release, kind of like what Oroville is doing right now with what’s going on up there.”

To help with the safety, the MWD bolted some rocks to the side of cliffs near the dam and conducted a routing study a few years ago to see if there were erosion or overtopping concerns.

“The routing study, what it does is it kind of models the water going over the top of the dam and what potentially kind of erosion, like what happened in Oroville, could create,” Stephenson said.  “And there were no concerns.”

The east side of the dam has experienced some spalling, or erosion, of the concrete, but the MWD said it is damage caused to the original 1-foot archways.  In 2005-06 the MWD added a 2-foot thick dam behind that dam, so it is secure, Stephenson said.  “Our dam right now is a big blob of concrete, it’s 32 feet, it’s pretty damn strong, there’s no fear of it failing,” he said.

The MWD also has an operations plan from its engineer, Mike Rogers of Montgomery.  Watson and Harza, which instructs the district that if there is 12 inches of predicted precipitation and the dam is a foot from full, water needs to be released, Stephenson said.

“We have a pretty robust plan as far as any issue,” Stephenson said.  “It’s kind of funny the last conversation I had with reporters was drought, now we’re talking flood and the dam breaks.  And that’s how these things come.  Right now we’re actually hoping we get some of that rain up north.”

The MWD dam has approval from its engineer and experiences bi-annual inspections from the Division of Safety of Dams for the state of California, Stephenson said.  Right now, Stephenson still hopes to receive additional precipitation.

We’re certainly not out of the woods yet as far as drought and low lake level,” Stephenson said.

Recent Article about Damkeeper

I thought this was an interesting article on how the dam works, who controls it, and how they monitor it based on the precipitation we get from year to year. Article is courtesy of Kathie Portie of the Big Bear Grizzly.

Damkeeper uses computer technology in job
By Kathy Portie
Published: Wednesday, January 26, 2011 7:24 AM PST

The word damkeeper brings with it romantic notions of someone watching over a dam to make sure it doesn’t fail much the same way a lighthouse keeper keeps the light burning for ships that pass in the night.

But there’s more to being a damkeeper than plugging a hole with a thumb. Just ask Jim Weber, the damkeeper for the Big Bear Municipal Water District.

To be more accurate, Weber’s official job title with the MWD is mechanical and facility technician for Lake Patrol. He’s a welder by education and a mechanic by trade. Weber keeps the Lake Patrol boats afloat.

But one of Weber’s duties is the district’s damkeeper. That particular duty became a priority during the December 2010 storm that saw the lake rise more than 3 feet and trigger one of the largest lake releases in district history.

“It’s a 24-seven, 365 days-a-year job,” Weber says. “We always have to release some flow into Bear Creek.”

A lot of that time is spent testing equipment and instruments to keep them in working order. “It’s a lot of ready and wait,” Weber admits. Other duties include monitoring the flow of water into as well as out of the lake.

Weber says the job as damkeeper kind of fell into his lap. Weber is one of the longest-active employees at the MWD, having started his mechanic’s job in 1987. “In 1987 I monitored cracks and flows, but typically back then we released water to Bear Valley Mutual (Water Company),” Weber says.

In the 1990s Weber’s job expanded to include monitoring Bear Creek because of the trout issue. He built weirs, or monitoring stations along the West Cub and East Cub creeks that feed into the main Bear Creek, which begins at the end of Big Bear Lake at the dam. The job has since grown to include environmental monitoring of the TMDLs (total maximum daily loads) of nutrients and sediments flowing into the lake.

In the old days, damkeepers lived near the dams they watched over. The skeleton of the damkeeper’s house, completed in October 1890, can still be seen keeping a ghostly vigil over the dam just above the framework of the new bridge road. An original damkeeper’s log house was closer to the dam in 1887. It burned in February 1890. The house preceded a roadway over the dam. Access to the home was by boat or by traveling the road from the east until 1924.

The damkeeper needed to be nearby to adjust releases sent downstream to irrigate orange groves.

More than 100 years later Weber has the luxury of modern technology to do the same job. He’s able to adjust flows out of the lake by remote computer. He can check flows at eight weir stations at Snow Summit, Bear Mountain Golf Course, Boulder Creek, Metcalf Creek, Grout Creek, as well as other locations. He can also receive alerts at home on his home computer.

“It’s very important when releasing water from the dam that we need to know what’s going into the lake so we can maintain what’s going out,” Weber says. “Back in the old days, they sat up at the dam, waiting to adjust the flow. Typically that’s all they did. Now, from our desk, we can monitor what is happening and make adjustments.”

Weber says big flows like the major release at the dam in December, are still done on site for safety reasons. “In December you (usually) don’t see it a foot from the top,” Weber says about the lake level. “This is the most unique time right now in my 24 years at MWD. We’re monitoring things very closely.”

Where December was one of the wettest months on record with 30 inches of precipitation, January has been the opposite. “We’re getting a lot more evaporation,” Weber says.

Lake Manager Mike Stephenson says it’s not only the warmer temperatures, but the wind that is stepping up the evaporation.

Being a damkeeper is not something the average person can just study to become, Weber says. “I don’t know if there’s a class for it,” Weber says. “It’s not something you can walk into and know it.”

Stephenson agrees. “Lakes are like snowflakes, they all have different characteristics,” he says. “Every dam is unique in what’s downstream.”

Whether the MWD has to do another major release this spring depends on the weather. “A lot has to be taken into account,” Weber says. “The average we get back into the lake is 3 feet a year. If we get 3 feet back this year it’s more than the 1 foot below full we have now. We’re anticipating more water, but we’ve been in a drought now for about three weeks. The evaporation is baffling.”

With the ever-changing ebb and flow of precipitation in Big Bear Valley, the damkeeper and the rest of the MWD staff must continuously adjust their estimates. “We’re always looking at what the future precipitation may be,” Weber says. “There’s so much to prepare for.”

“So much at stake,” Stephenson adds.

Like all damkeepers before him, Weber is keeping watch, just in a different way. “Used to we had to go down there,” Weber says. “We sleep a lot better now.”

Big Bear Valley can sleep better, too.