By Kathe Malouf
Special to the Sun
Just as it does every year, the level of Isabella Lake is dropping rapidly. But this year, the diminishing water level can be attributed not only to weather, but to the Isabella Lake Dam Safety Modification Project.
The Army Corps of Engineers is hoping to begin work on the Borel Canal, an important piece of the Dam Safety Modification Project, sometime this fall. In preparation of that work, water started flowing out of Isabella Lake months ago.
According to Rick Brown, spokesman for the Army Corps of Engineers, the water level of Isabella Lake needs to be lowered to 72,000 acre feet by October 1 in order to work on the Borel Canal.
But before any work can begin, the Corps must first acquire the easement from Southern California Edison for the 1,300-foot section of the canal that runs under Auxiliary Dam.
And that hasn’t happened yet, although the Corps and SCE have been in negotiations over the easement acquisition since early 2016.
Isabella Lake peaked this year on May 15 at a level of about 261,000 acre feet, which is about 100,000 acre feet lower than last season.
With the relatively low lake level, the Corps decided to proceed with their plan to work on Borel this year. Shortly after the lake peaked, the Corps requested that the Kern River Watermaster increase the releases in order to drop the lake to the Corps’ targeted level of 72,000 acre feet by Oct. 1.
“In order to have the lake at an acceptable level for the Borel work and to make the best use of the water that was being released, we needed to begin that draw down process in May,” Brown said, adding that waiting any longer than late May to start the lake draw would have jeopardized the scheduling of the Borel easement work, which would have pushed the work back into the winter of 2019/2020.
Early this week, Isabella’s water level dropped below 94,000 acre feet.
“By completing the Borel work this winter, the Corps avoids postponing that piece of the project for a full year and running the risk of delaying the overall project as well.”
The easement grants the right to enter the land owned by SCE that holds the portion of the Borel Canal that runs immediately upstream, through and immediately downstream of the Auxiliary Dam.
Once the Corps acquires the easement from SCE, Brown said they will seal the existing Borel conduit through the Auxiliary Dam by filling it with concrete, and abandoning the sealed conduit in place. In addition, the Corps will demolish and/or fill in portions of the Borel Canal immediately upstream and immediately downstream of the Auxiliary Dam.
The Borel work is vital to the Isabella Dam Safety Modification Project.
“All of this work will address the significant seepage and seismic safety concerns along the conduit that could lead to a breach of the Auxiliary Dam if not corrected,” Brown said.
If all goes according to the current plan, work is expected to begin in October and will take approximately 4 to 6 months to complete. With work being completed by next April and weather permitting, Brown said lake levels would be allowed to rise again to the restricted pool of 361,250 acre feet. Brown noted that the Corps scheduled the work during the fall and winter months to minimize impacts to Isabella Lake recreation season.
Despite not yet having the easement from SCE, Brown said the Corps decided to move forward with the lake draw.
“If we did not start drawing down the lake at the end of May but reached an agreement with SCE later this summer, it would be too late to start the drawdown to 72,000 acre feet by October 1, and we would miss our window of opportunity to conduct the work this fall/winter,” Brown said. “It is a calculated risk, but one the Corps is comfortable with, keeping in mind our goal to not delay this part of the project for a full year.
Brown reiterated that work on the Borel Canal won’t happen until the Corps acquires the easement from SCE.
“We cannot and will not move forward without the easement from SCE,” Brown said, adding that negotiations with SCE continue.
Brown said that it is still possible that the Corps will not get the easement to perform the work this fall. Should that happen, the work will be delayed until next year – the fall/winter of 2019/2020.
“We remain optimistic that we can perform the Borel work this fall and winter,” Brown said.
The Corps identified the need to acquire and abandon the 1,300-foot easement in 2012, but at that time SCE planned to continue operations of the Borel Canal. In August 2014, SCE approached the Corps to reevaluate that plan and start negotiations for the acquisition of the easement.
If the Corps and SCE cannot come to an agreement, a new tunnel around the Auxiliary Dam would have to be constructed; something that would add cost and time to the Dam Safety Modification Project.