Sediment flowing down the Klamath River from dam removal prompted officials in Siskiyou County, California, to declare an emergency last week over water quality.

“It is hereby proclaimed that a local emergency now exists throughout Siskiyou County as a result of impacts to Klamath River water quality and potential impacts to air quality related to Lower Klamath Dam Removal activities,” the County Board of Supervisors stated in a proclamation approved by a 4-1 vote Tuesday.

Three dams on the river are being removed this year, while a fourth was removed last year, in order to improve fish passage and water quality. Iron Gate Dam, downriver of the other three dams, is about 23 miles southeast of downtown Ashland. Sediment that had backed up over the decades in reservoirs behind the dams has flowed downriver since lake levels were lowered in anticipation of dam removal this year.

Sediment flows muddied the river, prompting concerns from the public.

The county declaration now will go to the California Office of Emergency Services and Gov. Gavin Newsom, asking them to “make available any Federal or State assistance for the recovery from this disaster.”

The board is asking the state to monitor air quality, water quality and residential well-water quality for the duration of the project. Commissioners had concerns that sediments left behind in dry lake bottoms would dry and become airborne.

Requests for comment from communications personnel with the state emergency services office and Siskiyou County were not returned.

County sampling of river water in late January and afterward found arsenic and lead levels exceeding drinking water standards at four of six sites downriver of the dams. The sampling also found concentrations of arsenic, lead, aluminum, chromium and nickel exceeding baseline readings that were taken before the drawdown of water behind the dams carried sediment downstream.

The proclamation stated that “it is not safe to consume the Klamath River surface water, and it is advisable to stay out of the Klamath River.”

The company removing three dams on the river, the Klamath River Renewal Corp., and the California State Water Resources Control Board have responded to concerns.

“Before dam removal plans were approved, state and federal agencies engaged in a rigorous evaluation of the sediment chemistry in the reservoirs,” the company said in a written statement issued last week. “The results of a variety of analyses indicated that, when released, the impounded sediments from the three reservoirs do not contain significant toxins and would not pose a significant threat to downstream communities or the environment.

“There are presently no drinking water sources that pull directly from the Klamath River, and constituents in mobilized reservoir sediment are not expected to leach into groundwater wells.”

The water board has issued an updated statement addressing frequently asked questions about the project.

“Based on current conditions and available water quality data … it is unlikely that recreational activities in the Klamath River will lead to adverse health effects from dam removal related sediment in the water,” the agency stated. “Nonetheless, as a general rule, ingestion of untreated river water should always be avoided and water safety should be observed.”

The agency stated that only one public drinking water system, at the Interstate 5 Collier Rest Area near Hornbrook, had been drawing from the river, but that replacement water was being made available.

“Public drinking water systems are not being affected by the temporary water quality issues in the Klamath River,” the water board stated. “Additionally … the sediment release is not anticipated to compromise downstream groundwater wells.”

The agency stated that river conditions have been significantly impacted, but that water quality is expected to improve over past conditions.

“This temporary impact to the river is outweighed by the substantial long-term benefits for water quality, fish and other aquatic resources that the removal of the dams will bring,” the water board stated. “Modeling indicated that, even in the worst-case scenario, temporarily increased sediment levels would result in less than 10-percent fish mortality.”

The drawdown of water from the lakes behind the dams, and the resulting release of sediment, was timed to minimize impacts to coho and Chinook salmon populations, with winter river flows expected to help flush sediment to the Pacific Ocean. In the meantime, river tributaries can provide refuges for salmon.

Prior to the drawdown of lake levels, fish rescue and relocation actions took place in the river.

An estimated 5.5 million cubic yards or more of silt, clay and sand will be released as a result of the project. While the finer elements are expected to be washed out to the Pacific Ocean in the first half of this year, coarse material might take longer and might settle in some locations, with sediment concentrations higher than normal for up to two years.

The project removed Copco No. 2 Dam last year, to be followed by the removal of Copco No. 1, Iron Gate and JC Boyle dams this year. Copco No. 1 was built in 1918; Copco 2 was built in 1925; JC Boyle was built in 1958, and Iron Gate was built in 1962. All are hydroelectric. All blocked fish passage. All are in California except for JC Boyle, which is in Oregon about 15 miles southwest of Klamath Falls.

PacifiCorp, the former owner of the dams, gave them up rather than seek relicensing and take on the associated cost of providing fish passage. The removal of the dams and completion of related work is funded with $200 million from PacifiCorp and $250 million from the state of California.

To view the county proclamation, visit co.siskiyou.ca.us. To view the water board’s questions and answers, visit bit.ly/3vzr2XP.