Water quality and surface hydrology of freshwater flow systems in Southwest Alaska: 2008 annual summary report

Shearer, Jeff; Moore, Claudette

The Southwest Alaska Inventory and Monitoring Network monitors freshwater systems in five national park units: Alagnak Wild River, Aniakchak National Monument and Preserve, Katmai National Park and Preserve, Kenai Fjords National Park, and Lake Clark National Park and Preserve. To date, most of our efforts have focused on protocol testing for water quality monitoring on Lake Clark and hydrologic monitoring on Naknek and Brooks Lakes. In 2008, 30 randomly selected, spatially balanced lake profile sites on Lake Clark were measured monthly from June through August between the surface and 50 m for water temperature, pH, specific conductivity, dissolved oxygen, and water clarity. Water quality parameters were stable between sites and months throughout the lake although water clarity decreased with proximity to glacial tributaries and as summer progressed, reflecting increased glacial melting due to increased air temperatures and solar radiation. Continuous water temperature monitoring in Lake Clark has been ongoing since September 2006. Water temperature data depict summer stratification and reverse stratification during winter, but there have been no indications of thermocline development. Water temperature monitoring was expanded to Naknek Lake in August 2008 but data were not available for analysis during the preparation of this report. Water level and discharge measurements were continued on Naknek and Brooks Lakes in 2008. Water level measurements were converted into estimated lake discharge based on stage discharge rating curves developed in 2006-07 by the U.S. Geological Survey while discharge measurements were used to refine rating curves. Continuous water quality and water level monitoring was conducted on Exit Creek from June 9, 2008 to September 30, 2008 to examine natural variation in water quality parameters due to diel glacial melting. Little variation in water quality parameters was observed that could be attributed directly to diel glacial melting. Early to mid-September precipitation events, and subsequent increased stream flow, was responsible for much of the variation observed within the data set. Monitoring in 2009 will focus on incorporating water chemistry analytical methods and tributary monitoring with lake profile and continuous water temperature monitoring to develop a more comprehensive approach to examine large freshwater flow systems (e.g. large lakes and their corresponding components – tributaries, outlets, and contributing lakes).

Water quality and surface hydrology of freshwater flow systems in Southwest Alaska: 2008 annual summary report

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