Rough Fire And El Nino Pose Problems For Pine Flat Lake

Jan 26, 2016

Last summer the Rough Fire grew so large that fire crews from around the world came to the Sierra Nevada east of Fresno to fight the blaze. Today the area is still feeling the effects of the 150,000 acre burn. And as FM89’s Ezra David Romero reports El Nino is bringing a whole new set of problems to the area

Pine Flat Lake was built in 1954. The artificial lake was originally built for flood control, but it's also used for irrigation, groundwater recharge and and recreation.
Credit Ezra David Romero / Valley Public Radio

Pine Flat Lake is rising about a half a foot a day.  Recent rain and snow are slowly filling it up.  

“The storms have been fairly regularly spaced and they’ve been bringing some much needed water into the lake,” says Pine Flat Lake Manager Jeromy Caldwell.

He and I are on a boating trip on the lake. With heavy storms in the forecast, Caldwell is expecting lots of water to flow in soon.  At the moment there’s only about 190,000 acre feet of water in the lake. But the reservoir has a capacity of a million acre feet.  That’s over 325 billion gallons of water.  With the water level rise comes a problem: debris and sediment from the burn area.

The US Army Corps of Engineers is worried that increased amounts of brush, logs and groundcover will flow into the reservoir. That debris can be harmful to people fishing or skiing on the lake. Caldwell says the Corps has a solution for debris.

"What happens in the burned scar area impacts everything downstream: sediment, water quality, ability to store water, how it's used downstream."- Steve Haugen
Pine Flat Lake sits in the foothills east of Fresno. The lake is used for fishing, boating and water sports. It also provides water to farms and municipalities in the Kings River watershed.
Credit Ezra David Romero / Valley Public Radio

“We have a floating boom and as you can see we’ve got some smaller debris now that is being caught,” says Caldwell. “The larger debris can cause hazards to boaters and it can also cause problems with the operation of the dam.”

The boom spans the width of the lake and is made out of 10-foot plastic buoys. Hanging from each orange buoy is a two foot metal grate stopping the flow of debris into the lake.

The boom was installed in late 2015 to prevent debris from flowing into the lake.
Credit Ezra David Romero / Valley Public Radio

ROMERO: “That’s a pretty big log right there.”

CALDWELL “It is pretty long. And so it could cause some problems for a boater that happened to hit it.”

"We won't know the full extent of that problem until probably five to 10 years out as that sediment makes it way down through the river system." - Steve Haugen

Sediment is the other problem. Fine particles dissolve in runoff as it flows through the watershed. Eventually sediment settles on the lake floor. All this mud could make the lake smaller.

“There is additional sediment expected to come into the lake because of the fire,” Caldwell says. “You can see some brown colored fine sediment that’s building up along the river.”

At this point there’s not much that can be done to stop the particles from coming into the lake. Steve Haugen is the watermaster for the Kings River Water Association. He says the consequences that come with the increased sediment from storms over a burn area are huge.

“Out of a 10 year storm we could get upwards of 2,000 acre feet worth of sediment coming into Pine Flat. That settles on the bottom and displaces 2,000 acre feet of water,” says Haugen.

And that’s just from one storm. El Nino is supposed to bring many storms. That may not seem like that much of a loss of water either, but with such low reservoir levels every drop matters. All that water is accounted for and a lower holding capacity in the lake means less water for farms and towns.

The Kings River flows into Pine Flat Lake. As it flows through the Sierra Nevada it picks up debris along the way.
Credit Ezra David Romero / Valley Public Radio

“What happens in the burned scar area impacts everything downstream: sediment, water quality, ability to store water, how it’s used downstream,” Haugen says.

Plus, once that sediment settles, it’s really hard and expensive to remove. Haugen also says the irregular increase in organic matter into the lake creates a problem for wildlife.

“As that organic matter decays it actually removes oxygen from the water that would be otherwise available to fish or other aquatic life,” says Haugen.

Even if California gets a bunch of heavy El Nino storms this year the problem with increased sediment flows doesn’t just go away next year.

“We won’t know the full extent of that problem until probably five to 10 years out as that sediment makes it way down through the river system,” Haugen says. “The consequences of these fires are long duration.”

Haugen says the sediment dissolved in the lake water eventually makes it out of the dam into grower’s fields and overtime can clog farm machinery and water pumps. But to what extent we won’t know for years to come.