John C Boyle Reservoir
- Klamath County)
(From Atlas of Oregon Lakes, Johnson et al. 1985) John C. Boyle Reservoir is a large hydro-electric project which was built in the late 1950s by Pacific Power and Light Company. Known originally as Big Bend Reservoir, for a large meander in the Klamath River, it has since been renamed in honor of the chief engineer of construction. Most of the water resource development in the Klamath Basin has been for irrigation and there is a large network of dams, reservoirs, and delivery systems for this purpose. In contrast, John C. Boyle Dam and Reservoir and the Link River Dam at the head of the Klamath River were constructed primarily for power production.
The John C. Boyle powerplant, located five miles downstream from the dam, has an 85,000 kilowatt capacity. Streamflow through the reservoir is regulated primarily by outflow from Upper Klamath Lake and there are diversions upstream for irrigation. Large diurnal fluctuations in water level are caused by operation of the powerplant upstream at Link River Dam and downstream at the John C. Boyle powerplant.
The shape of the reservoir is elongate, with a narrow southern end which reaches depths greater than 40 feet behind the dam, and a much wider northern end with depths of 10 feet or less. The reservoir receives the discharge from Klamath Lake and therefore shares many of the same chemical and biological characteristics. There is also a considerable contribution from groundwater which dilutes the Klamath River water. This seepage averages 10 to 25 percent of the flow on an annual basis, but can contribute as much as 25 to 50 percent during the summer low flow period. The concentrations of major ions and conductivity are very high. The concentration of phosphorus and chlorophyll are also very high, and indicate highly eutrophic conditions (nearly hypereutrophic). Water transparency is very limited and is a further indication of eutrophic conditions. The short retention time noted here is probably not representative of circulation throughout all segments of the reservoir, as indicated by the extensive growth of rooted macrophytes in the shallow areas.