Water Quality Markedly Improves Post Dam Removal
- The Yurok Tribe
- 14 minutes ago
- 3 min read
Klamath River Sees Major Decrease in Toxic Algae, Heavy Metals & Nutrients
Water quality in the lower Klamath River has significantly improved since the removal of four upper Klamath dams, according to preliminary results collected by the Yurok Tribe Environmental Department.
Reductions in the concentration of heavy metals, algae-derived toxins, nutrients, and suspended sediments have all been measured in the two years since reservoir drawdown.
Before dam removal, algae that bloomed behind Iron Gate dam produced high levels microcystin, a powerful liver toxin which is harmful to people and wildlife downstream. As a result, the Klamath mainstem was routinely posted with warnings to avoid human contact.
“We’ve seen a significant decrease in the levels of microcystin throughout the Reservation since dam removal,” said Yurok Tribe Environmental Department Water Program Manager Josh Cahill said. “People no longer need to worry about health effects from direct contact with river water with regard to microcystin.”
Environmental analyses leading up to the dam removal project predicted short-term effects to many Klamath River water quality constituents during the deconstruction process as sediment was released downstream followed by longer-term benefits as the river recovered. These included estimates of turbidity, phosphorous and nitrogen downstream.
As predicted, the release of dam-held sediments increased the concentration of certain less-toxic metals such as iron and aluminum, and some dissolved oxygen decreases were detected. However, after dam removal, the Yurok Tribe Environmental Department has measured reductions in heavy metals, including mercury and aluminum, total phosphorous and total nitrogen levels, as well as turbidity, which is a measure of suspended fine sediment.
“Measured concentrations of all analyzed metals on the Reservation are presently reduced compared to pre dam removal levels,” Cahill said.
Klamath River water quality continues to be impacted by many factors including current and historic logging practices, agriculture, the legacy of the mining industry, and the amount of water in the watershed any given year, but the improvements in the short time following dam removal show the positive effects of dam removal.
In addition to water quality improvements, coho and Chinook salmon, steelhead, and lamprey have repopulated the stretches of the Klamath upriver of the former dam footprint. Located in Oregon, this includes tributaries such as the Williamson, Sprague and Wood Rivers near the top of the watershed, located in the ancestral territory of the Klamath Tribes. This repopulation of up to 420 stream miles upriver from the location of the dams that were removed has exceeded even the most optimistic short-term predictions of fisheries experts. Although a promising start, the Klamath still faces a long road to large-scale ecosystem restoration success.
With improved water quality and access to formerly blocked habitats following dam removal, populations of salmon, steelhead, Pacific lamprey, and other native fish such as sturgeon are expected to increase gradually over time. As with the recovery of at risk fish stocks on other rivers, increases are expected to unfold unevenly due to the numerous factors that affect run size, including annual precipitation, diversion levels, ocean conditions, and prevailing weather patterns.
As the Environmental Department continues to monitor and collect data, it will get a better understanding of the full impacts of dam removal on water quality.
The Yurok Tribe Environmental Department has 20 years of pre-dam data to draw from. The data used in this story was derived from Water Division’s four water quality monitoring stations on the mainstem Klamath River. They also operate six water quantity monitoring stations on Klamath tributaries Trinity River, Blue Creek, Pecwan Creek, McGarvey Creek, and two stations on Terwer Creek. There is also a gaging station in the Estuary at Requa and in upper Klamath wetlands, which are headwaters to streams that some communities rely on for drinking water.
This sampling aligns with results that have been collected by the Karuk Tribe Water Quality Department further upriver since dam removal.
The Yurok Environmental Department also has plans to add monitoring capabilities in 15 additional tributaries with the goal of assessing and improving drought resilience for the Tribe.
“The Environmental Department’s purpose is to monitor and protect water resources of the Klamath River, its tributaries, and its wetlands,” Cahill said. “The main objective is to make sure Yurok lands and waters, culture, and people are protected in perpetuity.”
Cahill has worked in water quality monitoring for the last five years. Previously, he had worked as a fisheries biologist. “I thought that I was going to go back to fisheries but I really liked water quality and the social component of this job so I decided I wanted to stick it out. The community impact means more to me than I thought. What we do affects the community day to day.”
YUROK TRIBE
190 Klamath Boulevard • Post Office Box 1027 • Klamath, CA 95548
FOR IMMEDIATE RELEASE
Contact:
Yurok Tribe - Matt Mais
(707) 954-0976
