Klamath Water Users perspective on
functions of Klamath River dams, and consequences of dam removal
A River "Upside Down" – PacifiCorp Model Provides a Klamath Reality Check
Recent water quality modeling developed by PacifiCorp provides a glimpse into Klamath River dynamics that may force policy makers to take a whole new look into how the system can be managed. The Klamath Hydroelectric Project (Project) consists of seven mainstem hydroelectric developments on the upper Klamath River and one tributary hydroelectric development. PacifiCorp owns and operates the Project under a single license issued in 1956 by the Federal Energy Regulatory Commission (FERC). The 50-year license (FERC Project No. 2082) expires on March 1, 2006.
PacifiCorp has developed flow and water quality models for the Klamath River, specifically from Link Dam to Turwar, California. The models developed by PacifiCorp can analyze water quality from Link Dam to Iron Gate Dam and below, and show how the PacifiCorp facilities contribute to or control water quality conditions in and downstream of the dams. The models can address questions related to PacifiCorp operations including (1) whether and how operations might contribute to water quality conditions, and (2) whether and how operations might feasibly contribute to water quality improvements.
Utility Of Maintaining Dams In Place
According to the modeling, the PacifiCorp dams in the Middle Klamath are serving important functions. Some of those functions are attributable simply to the fact that they create a series of lakes. Turbidity, for example, diminishes as water moves through the system; turbidity can be a surrogate for particulate matter, including dead algae and other nutrients.
Particulate organic matter that originates, or is a result of nutrients released from Upper Klamath Lake, agricultural return flows, and municipal and industrial inputs in the Klamath Falls area is to a large extent trapped by system reservoirs (settles out), reducing the overall nutrient load to the reaches below Iron Gate Dam. All of the reservoirs are "productive," and organic loads are elevated in all of them; however, Upper Klamath Lake is in general several times as "productive" as Iron Gate and Copco reservoirs. Further, Upper Klamath Lake is a much larger body of water with a large surface area, and can produce appreciable organic inputs to the Klamath River. Comparatively, Iron Gate and Copco reservoirs have much smaller surface areas and, although productive, do not yield the same loading potential as Upper Klamath Lake. These reservoirs thus have a considerably smaller impact on releases to the Klamath River than Upper Klamath Lake.
Consequences of Dam Removal
PacifiCorp’s findings suggest that, under current conditions - even if all the dams were removed below Link Dam - the resulting river reaches could not assimilate or retain anywhere near what the dams now assimilate or retain. Without the dams, there is potential for water with substantially impaired water quality to flow downstream to the middle Klamath River reaches. Without the current impoundments in place, water would reach the area of Iron Gate Dam in two to three days versus six to eight weeks. The dams are beneficial for water quality, because upstream water quality is impaired, and the reservoirs trap appreciable amounts of matter, thereby reducing the load to downstream reaches.
If Iron Gate Dam were removed, PacifiCorp modeling suggests that the river below Copco I and II developments would be slightly warmer than the river below Iron Gate Dam because Copco is smaller and has a smaller cold water pool. There would be unknown silt impacts downstream of Iron Gate Dam upon removal. There would still be "thermal lag," even without Iron Gate Dam, since the Copco Dam would continue to have a thermal lag effect. Finally, cold water in Iron Gate Dam is a source of water for the fish hatchery, so removal would result in no cold water supply for the hatchery. Removing Iron Gate Dam would restore approximately eight river miles, with resultant increase in mainstream reaches, and some spawning habitat.
The habitat quantity and quality outputs from another model are being used to focus on dam and reservoir passage efficiencies so that passage options can be assessed. The model incorporates both habitat data and fish passage survival through Klamath Hydro Project structures to estimate fish production in specific reaches or areas of the basin. The model can explore how different assumptions affect model results; this model is being used primarily as a "gaming" tool to assess the effects various fish passage options have on fish production. KWUA will continue to gather further information on this model, which may prove to be a useful tool to evaluate watershed-wide actions that can benefit water quality and fish habitat.
Participants in recent PacifiCorp modeling presentations have noted that the Klamath River behaves as if it is "upside down", with characteristics that differ from other river systems.
– Source:2/5/04 PacifiCorp Briefing Material -
Klamath Water Users Association
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