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Individual Highlight

Vulnerability of High Elevation Lakes of the Sierra Nevada to Atmospheric Acidic Deposition

Photo of Class I and II Wilderness areas and lakes evaluated for acidification vulnerability. Glen Shaw, USDA Forest ServiceClass I and II Wilderness areas and lakes evaluated for acidification vulnerability. Glen Shaw, USDA Forest ServiceSnapshot : In at least some years, hundreds of wilderness lakes are likely receiving acid loading in excess of their buffering capacity. The most vulnerable lakes identified in this study are in the Southern Sierra Nevada where nitrogen deposition is highest.

Principal Investigators(s) :
Fenn, Mark E. 
Research Location : California Sierra Nevada Wilderness Areas
Research Station : Pacific Southwest Research Station (PSW)
Year : 2014
Highlight ID : 680


Large areas of California forests and other ecosystems are exceeding critical deposition loads for atmospheric nitrogen inputs. Ecological effects of these excess atmospheric nitrogen inputs are most commonly related to "nitrogen as a nutrient" effects, or eutrophication responses. Because of the dilute waters of high-elevation lakes in the Sierra Nevada of California, the acid neutralizing capacity of these water bodies is very low. As a result, even low levels of nitrogen or sulfur deposition from air pollution results in vulnerability to acidification. Sixteen percent of the 208 lakes from Class I and II Wilderness areas studied were in exceedance of the critical load for acidification. The most vulnerable lakes were located in the Sierra and Stanislaus national forests. Atmospheric deposition inputs are projected to exceed the estimated critical loads of the more sensitive lakes and catchments in this area for the foreseeable future, even though nitrogen oxide emissions in California from the transportation sector have decreased dramatically in recent years.

Forest Service Partners

External Partners

  • Jim Sickman, UC-Riverside, co-author