Success Lake near Porterville might be allowed to fill up again now that the Army Corps of Engineers has ruled that the dam is unlikely to collapse in an earthquake.
The Corps came to that conclusion in November.
In February, it will announce to farmers how much water can be stored in the lake this year after several years of keeping the lake low on purpose.
Since 2004, the Corps has kept Success Lake low for fear an earthquake might rattle the earthen dam so badly it would start falling apart, potentially sending a flood down the Tule River toward Porterville.
But after drilling bore holes to test soil and doing earthquake damage analysis, the Corps is confident the dam won’t slump in an earthquake, said Corps project manager Darren Suen, a civil engineer.
And water seepage has been ruled out as a problem, he said.
The main risk is “overtopping” in which an earthquake could cause water to spill over and start washing away the dam, Suen said. Later this year, the Corps will release an assessment of the risks and what can be done about them.
Importantly for farmers, the report will recommend how high the Corps should keep the lake from now on.
With catastrophic seismic fears put to rest, the Army Corps’ “body language” hints at increased storage, said Dan Vink, manager of the Lower Tule River Irrigation District.
The dam, built in 1960s, can hold 82,000 acre-feet of water. Last year, the Corps allowed only 65,000 acre-feet in the lake.
“I’m cautiously optimistic” that dam operators will fill the lake or at least go higher than last year, Vink said.