Army Corps installs pump to handle unexpected seepage from Isabella Dam

October 9, 2023
by Lois Henry
A temporary pump to move excess seepage over the Isabella Auxiliary Dam back into the lake. COURTESY: Army Corps of Engineers
Lois Henry

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For the first time in six months, Gerald Wenstrand doesn’t have a river flowing through the pasture at his ranch situated just below the Auxiliary Dam at Lake Isabella.

The Army Corps of Engineers, which owns and operates Isabella Dam, finally installed an extra pump to move seepage coming through the base of the dam back into the lake. The pump system it had installed as part of the $300 million dam reconstruction project was too small to handle the amount of water coming through the earthen dam.

The fix comes six months after residents first began complaining to the Army Corps that the seepage as causing sinkholes near homes, damaging septic systems, eroding land and causing massive weed growth and mosquito infestations. The Army Corps had initially told residents another pump wouldn’t likely be installed until December, according to what residents told SJV Water.

One resident who has had to have her septic system pumped four times since April, said it’s great that the Army Corps has contained the seepage but groundwater levels are so high now that her leech field is shot.

“Because the water table is so high, they have do to an engineered septic and the estimate for a new septic and leech field is over $40,000,” said Julie Chapman, who’s lived in her home on Perdue Avenue since 1998 and has never seen the water situation this bad. “That’s not something I can afford.”

She hasn’t had time to look into filing a claim yet. Wenstrand said he was told by an Army Corps spokesman that claims must be verified by two independent, third-party experts.

“That’s all out of pocket money,” to the residents making any claims, he texted.

Chapman was frustrated by that. “It’s sad we have to work so hard to be compensated for something that they did,” she said.

Aerial view of seepage running west from the Auxiliary Dam taken in September. Courtesy: Joanie Etcheverry

Joanie Etcheverry, whose family owns land below the dam, said it’s hard to even contemplate filing a claim at this point because the damage is still ongoing.

“Here we are and it’s almost winter and the ground’s still wet so nothing’s going to dry out for a while,” she said.

Like the other residents, she’s happy the seepage is being contained but wondered why it didn’t happen sooner.

“It’s irritating,” she said. “They could have stopped this right at the beginning. Why flood us all out when they could have fixed it?”

The fix, though, is just temporary with no date for a permanent one, according to an Army Corps press release issued Oct. 6. Questions emailed to an Army Corps spokesman were not responded to in time for this article.

“After further evaluation, we plan to install a more permanent solution within six to twelve months,”  Henri Mulder, a geotechnical engineer with the Army Corps, who works out of the Isabella office, is quoted in the press release.

Though the Army Corps states it did extensive modeling on inflows to the lake, it blames the excess seepage on the fact that Isabella filled up faster than anticipated during this year’s record wet winter.

That didn’t make a lot of sense to residents. At some point, the lake was going to fill, which should have been factored into the seepage planning.

“They built this dam to be able to withstand a 1,000-year flood but didn’t put in a proper sized pump to handle the seepage?” Wenstrand said previously.

One of the main reasons the Army Corps rebuilt Isabella Dam in the first place was seepage through the Auxiliary dam that was causing erosion.

The Army Corps has stressed that the current seepage is not causing erosion and poses no dam safety threats.

SJV Water is an independent, nonprofit news site dedicated to covering water in the San Joaquin Valley. Get inside access to SJV Water by becoming a member.


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