Written by by Juliet Grable at opb.org
Iron Gate, the lowest of the Klamath dams, was breached first on Jan. 9, followed by J.C. Boyle in Oregon, and finally, Copco 1. Draining the three reservoirs marks another milestone toward the removal of dams in the Lower Klamath Project.
“A lot of sediment mobilized and moved through the system, exactly according to our plans and our projections,” said Mark Bransom, CEO of Klamath River Renewal Corporation, during a press conference on Thursday morning. “We’re very pleased with the progress that has been made on the drawdown.”
In total, KRRC expects 5 to 7 million cubic yards of sediment — the same amount that the Klamath River would normally drain in a single year — to wash downstream over a short period of time. The material, composed mostly of very fine silt and dead algae, has imbued the river with a dark coffee color.
For several days last week, dissolved oxygen levels in the first 20 miles below Iron Gate dam hovered close to zero. Decomposing algae rob water of oxygen, as do oxidizing minerals. As the last of the reservoirs drained, they released oxygen-poor water, as well.
“The bottom of reservoirs have this anoxic layer — this layer of water that basically doesn’t have any oxygen in it,” explained Desiree Tullos, professor of water resources engineering at Oregon State University.
The river becomes re-aerated as it tumbles over rocks; major tributaries like the Shasta River also bring in oxygenated water to the mainstem of the Klamath River. “The farther away you get away from the reservoirs, the less and less impact you’ll have,” said Tullos.
Experts expected oxygen levels to dip, which is why drawdown was initiated in the winter months.
“We don’t have adult salmon in the river system, and most of the juveniles are up in the tributaries and have not yet started their out-migration to the ocean,” said Bransom.
The draining of the reservoirs has left behind large “mudscapes,” especially in the broader Copco Lake footprint. In late January, nearly a dozen deer became entrapped in the mud and perished around the former reservoir. California Department of Fish and Wildlife has since installed fladry — strings of small flags that flap in the breeze to dissuade animals — at several locations.
Thousands of fish that inhabited the reservoirs have also died. These are mostly non-native species, including yellow perch, crappie, and bass that thrive in calmer, warmer water.
“It was always expected that these species would not persist,” said Dave Coffman, geoscientist for Resource Environmental Solutions, or RES, during the press conference.
Concerns over water quality
During a tense and lengthy public meeting on Feb. 13, several area residents expressed concerns about the entrapped animals and scores of dead fish, wells that have gone dry in the Copco Lake community, and the possibility of contaminated sediment being exposed and making its way downstream.
William Simpson, founder and CEO of the nonprofit Wild Horse Fire Brigade who lives near Yreka, California, referenced test results of a sample collected by one of his neighbors in late January that revealed elevated levels of several metals, including chromium.
“It’s shocking that you even bring up the whole idea of water quality when the only testing really going on is turbidity, flow and oxygen, when you have all these other things that need to be considered, which we know are in the sediment,” said Simpson, who has been publishing strongly worded op-eds in Siskiyou News criticizing KRRC and dam removal.
Coffman cautioned against jumping to conclusions about Simpson’s water test results without knowing more about how it was collected, how it was taken care of, and whether or not it was filtered.
“There’s not enough information associated with it for it to be useful,” said Coffman, adding that more than a decade of work went into evaluating the effects of dam removal on state waters. “That [work] included a lot of sediment and water quality testing on the stuff that’s impounded within the reservoirs.”