It flows downhill
Mono County prepares for flood danger.
The potential Godzilla El Nino brings with it increased risk of flood, something Mono County is beginning to prepare for.
Chalfant Valley has already been hit with flooding in July and in October, the result of small yet powerful storm cells that produce a lot of water in a short amount of time. Post-fire areas of Swall Meadows and Round Valley are contenders for flooding, too. The small communities on the foothills of the Sierra Nevada have lost to fire many of the plants and roots that hold the soil together. Without those anchors, the soil can easily get swept away in running water. A stream quickly becomes a wave of debris and mud.
Mono County Supervisor Fred Stump, whose district covers both Chalfant and Swall Meadows, has been talking with local agencies trying to prepare for the mass precipitation potential. But there’s not just one or two agencies and bureaucracies to deal with, but many.
When the water flows downhill, it passes through several lands with different land managers. In Chalfant, for example, the flood water in October wasn’t the result of rainfall in the valley or on the highway, which is managed by Caltrans. According to the Climate Research Division of Scripps Institution of Oceanography, on Oct. 18, 0.45 inches of water fell between 4,000 and 5,000 feet elevation, on Los Angeles Department of Water and Power (LADWP) owned land. A little higher up the mountain, the 7,000 to 8,000 foot elevations, managed by the Bureau of Land Management (BLM), picked up 0.86 inches, while 1 to 1.4 inches fell at the 9,000 and 10,000 foot elevations, Forest Service managed lands.
Caltrans is currently working to make sure its culverts are cleaned and ready to accept water. The culverts were cleaned after the October storm. “We are also analyzing where the water is coming from and how to handle the flow along our right of way and make sure that the flow of water continues along its natural course down the valley,” said Caltrans Public Information Office Florene Trainor.
Stump added that Caltrans is bringing in a hydrologist to look into the matter.
“Due to the natural terrain of the area surrounding Chalfant, controlling flow water is very challenging,” said Amanda Parsons, LADWP Public Information Officer. “LADWP is willing to discuss flood control in the area with Mono County, but it would be necessary for the other agencies present in the flood plain to also participate, since storm flows are present on their lands as well.”
LADWP was on-scene in Chalfant, digging a trench to the east of the community in the hopes of diverting the water. But this is not a permanent solution, and there may not be one.
The Forest Service said there’s not too much it can do, as the land it manages is the peaks and upper elevations where the rain falls, not the flood plains. The Forest Service monitors and clears highly vegetated or choked creeks to reduce the potential for flash flooding, said Inyo National Forest’s Public Affairs Officer Deb Schweizer. She said no such choke points have been identified in the White Mountain range specifically above the Chalfant area.
The BLM said it will be working with the LADWP to see if there’s anything else that can be done, but, “to completely eliminate the risk would be a huge undertaking” said Dale Johnson, Natural Resource Specialist for the Bishop Field Office. There are so many natural drainages and water paths in the area’s complex topography, it would be difficult to try and cap or dam one or two hoping it would be the fix. Johnson said water will find a way down, no matter what’s in the way.
BLM’s Land and Reality Specialist, Larry Primosch explained how flooding is being mitigated at Manzanar Historic Site with new culverts and by cleaning out debris from existing culverts to keep the water in its original channel. Primosch said he didn’t think culverts would be a solution at Chalfant, referring to the massive canyons that can fill with water and rip down the side of the 10,000-foot escarpment of the White Mountains. Primosch said a moat could be built around Chalfant, but that’s still no guarantee it would stop a flood from coming in.
Another issue during the October flood was the lack of sandbags or sand in Chalfant. Stump said bags and sand are being placed in eight different areas in the county including Swall, northern parts of the county and the Tri-Valley area of Chalfant, Hammil and Benton.
Swall Meadows and Round Valley could face big waves of water this winter after the Round Fire in February burned down most of the plant life that keeps the soil in place. Schweizer said the plants and other flora in area have had an entire summer to root and will hopefully alleviate some flood problems, if any, this year.
