How do you clean a massive fish screen that is larger than two school buses parked end to end? You can't use Comet, Lysol or steel wool pads.
It is a specialized project undertaken each year by the staff of Woodbridge Irrigation District.
The screen is installed just south of the district office on Lower Sacramento Road in Woodbridge. It allows Mokelumne River water to flow into district pipelines without bringing fish or river debris along for the ride.
The first step is to drain all 1,200 acre-feet of water in of Lodi Lake.
The district announced at a board of directors meeting on Thursday that the lake will be an expanse of mud from Feb. 1 until at least Feb. 21. The river channel from the lake to Woodbridge Dam will still hold some water. The city of Lodi will stop taking water for the surface water treatment plant during that period.
What about the actual cleaning job?
"The job is basically done with brooms and scoop shovels," said district manager Andy Christensen.
Mud, bits of leaves and varied other bits of organic matter build up on the screen as river water rushes through it throughout the year. That silt is scraped off of the 100-foot screen with a big push broom that looks something like an oversized squeegee. Then workers scoop it out by hand into a waiting dump truck and haul it away.
Next, workers will bring in a power washer and aim the spray at the fine mesh of the screen, like using a fire hose to clean a residential driveway. Nothing that isn't bolted on will remain.
This is the best opportunity district employees have to check the screen's mechanisms.
Christensen said the team has completed a brief pre-inspection and the to-do list is shorter than usual.
"We have a little more experience now at checking the system," he said. "We'll make any small repairs we need to. I don't know what they are yet; it's been underwater for 12 months."
The district will complete dam maintenance work at the same time.
The fish screen has been in place since 2007, and the dam was finished in 2005.