By Deb Murphy
The 500 cubic feet per second flows scheduled for the Owens River Gorge in late June have been postponed until later this month. But the impact of flows 10-times greater than what has been released hasn’t been postponed. What about the fish and their habitat?
According to California Fish and Wildlife biologist Steve Parmenter, the penstock between the Middle and Lower Gorge Power Plants has to be dried up for safety reasons as Los Angeles Department of Water and Power fix a mechanical problem. All this precedes the construction of a flume, scheduled for September, to begin restoring flows in the length of the gorge.
Parmenter is the go-to guy for trout in the Gorge; he’s been around since the litigation in 1991 that resulted, 24 years later, in putting water back in the once bone-dry Gorge.
“Brown trout need three things,” he said in a phone interview. “Cool, clean water, deep pools, more than three feet and gravel riffles,” providing a smorgasbord of aquatic insects. All of the above could improve with the planned flows.
That assumption isn’t theoretically. According to Parmenter, back in 2003, LADWP ramped up flows to 700 cfs in the Gorge over a period of a few days.
Once deep pools had filled in with sand, the riffles had become sand clogged. All that changed with the high flows. “The pools were scoured out,” said Parmenter. “The flows turned over the gravel and flushed out the sand.” He called the comparison between the 2003 flows and the proposed July flows as good, but not perfect.
The duration of this year’s flows is far longer, roughly two months compared to a few days. But, the mathematics of stream power indicates the proposed 500 cfs flows don’t have near the power of those in 2003, according to Parmenter.
“Big flows for months down a channel are good for habitat,” he said. “That’s not scientific, that’s anecdotal.”
So much for trout habitat, what about the trout?
“Fish do a pretty good job taking care of themselves,” Parmenter said. “The flows are high, but not out of the natural range. Fish hunker down and weather the storm.”
“With stabilized flows, the river loses its structural diversity,” he said, “holes fill in, flows across gravel riffles are slower.”
Parmenter noted the gorge has been either dry or subject to low flows for decades. There’s an obvious comparison to the Lower Owens River where efforts to restore an actual river have been stymied by controls.
Again, anecdotal evidence says the fishing experience could improve after the high flows. A few years after the 2003 release, Parmenter got a calls from anglers asking “what did you do, the fishing is great” in the Gorge.
Not everybody is convinced, however. Phillip Anaya’s concern has to do with the trout’s food source. “A big release will disrupt the hatch,” he stated in an e-mail, “washing out the hatch, limiting the food the trout eat.” Anaya and others want to see an environmental analysis done before the Gorge ramps up to 500 cfs.