Report addresses effects on groundwater

“Current studies indicate that the sediment stored behind the dams is not contaminated and would have no negative impact on downstream waters beyond elevated total suspended sediment (TSS) when the dam is breached, but further studies using a representative sampling program are necessary to examine sediments,” the report states.

Additional strategy regarding groundwater includes determining whether septic systems are used in the Klamath Basin and how they might be affected by changes in groundwater.
The final physical liability discussed in the report is the possible effects of dam removal and decommissioning on water quality in the Klamath River.

The water quality has been demonstrably poor in recent years, which is cited in the report.
“The water quality in the Klamath River from Upper Klamath Lake to the California state line is impaired due to pH levels, ammonia and nutrient concentrations, temperatures, dissolved oxygen, and chlorophyll a.”

The report states that water quality is “overwhelmingly influenced” by releases from Upper Klamath Lake and includes that several groups have suggested that removing the dams will improve water quality.

Liabilities related to water quality are listed as “Seasonal shifts in water temperature, with potential spring and early summer temperatures higher after decommissioning than current conditions; long–term elevated levels of TSS in the water column following dam removal; short–term water quality degradation during reservoir drawdown, with high TSS, low dissolved oxygen, and high nutrient concentrations; long–term water quality changes due to dam removal and restoration of natural stream conditions; environmental/regulatory compliance and permitting; and potentially contaminated sediments.”

The seasonal shift is assumed in the report to be a low liability because removing the dams will presumably return the river to pre-project conditions.

The report states that sediment erosion after dam removal would result in heightened levels of TSS in the water column and could also result in contaminant transport if in fact the sediment contains contaminants.

The report also claims that water quality would likely be degraded immediately downstream from the dams in the form of low dissolved oxygen and high TSS, which would likely affect aquatic life and other water users downstream. One other potential liability discussed is the influence of the Keno Reservoir and Upper Klamath Lake on water quality in the Klamath River after the dams are removed.

“Most modeling efforts predict improvements in water quality conditions following dam removal, however some indicate significant water quality impacts following dam removal due to the quality of water in the Keno Reservoir.”

The report states, “Many studies have addressed water quality in the Klamath River and within the reservoirs, and much data has been collected for the area covered by this report. Several water quality models have been developed for these reaches.”

The report’s authors, however, list in the data gaps “Limited water quality data exists to build existing models,” stating that the solution would be to “Develop a sampling plan designed specifically for model development.”

Other recommended actions include developing a refined water quality model that will allow an assessment of immediate and short-term impacts from sediment release and high TSS and also the development of a model to predict the long–term impacts on water quality below Keno Dam.