Assessing the Benefits of USDA Conservation Programs in the Upper Klamath River Basin and Central Valley of California on Ecosystem Services
September 2011 - June 2015
- U.S. Department of Agriculture Natural Resources Conservation Service, Resources Assessment Division
Deteriorating water quality in Upper Klamath Lake has a negative effect on the entire Klamath Basin ecosystem. Annual cyanobacteria blooms dominated by Aphanozoamenon flos-aquae result in severe dissolved oxygen fluctuations, basic pH, elevated ammonia concentrations and increased levels of algal hepato-toxins. The upper Klamath Basin contains the largest remaining habitat for the federally listed endangered Lost River and shortnose suckers, as well as redband and bull trout. Declining lake water quality has been implicated with juvenile sucker mortality and occasional adult fish kills. Poor water quality in upper Klamath Lake also influences the lower Klamath River, impacting federally listed coho salmon, Chinook salmon and other fish species. Upper Klamath Lake receives over half of its inflow from the Sprague, Williamson and Wood Rivers. Reaches of the Sprague River are listed as impaired under section 303(d) of the Clean Water Act for degraded water quality, which may be associated with increased sediment and phosphorus loading. Although Upper Klamath Lake was historically eutrophic because of phosphorus-rich volcanically derived soils, today Upper Klamath Lake and adjoining Agency Lake are both hyper-eutrophic due to algal blooms from high nutrient loading. The drainage of 10,000 ha of former wetlands that historically surrounded the lake is thought to have contributed to eutrophication. A variety of restoration programs and projects have been implemented along the UKRB to improve the health of the ecosystem. These include Klamath Watershed Partnership assessments of site-specific riparian and upland conditions; USDA administered Wetlands Reserve Program (WRP), Conservation Reserve Program, and Environmental Quality Incentives Program; and USFWS-funded restoration of floodplain connectivity, fence construction for livestock management, and streambank stabilization. These efforts are believed to provide direct and indirect benefits to aquatic ecosystem health. However, their effectiveness at mitigating impacts to water quality and habitat have not been evaluated. In addition, quantification of restoration effects will provide important justification for continued financial and community support in the watershed. Regional climate change models forecast increases in air temperature and changes in precipitation and vegetation patterns in the Klamath River Basin in the future. Summer air temperature was predicted to increase 1.2 - 2.7 degrees C over the next 20-30 years and 3.2 - 6.6 degrees C by 2075. Changes in precipitation are less certain, however, snowpack is expected to decline and summers are expected to be drier than they currently are. The potential impacts to regional water quality and endangered fish populations from climate change are unknown. The objectives of this project are to use the Soil and Water Assessment Tool (SWAT) model to estimate reductions in soil and nutrient loading to Upper Klamath Lake that could potentially be achieved through WRP or other wetland restoration programs in the Upper Klamath River Basin.