Water quality and surface hydrology of freshwater flow systems in Southwest Alaska: 2009 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 field testing and modifying protocols for water quality and hydrology monitoring on high priority lake systems. In 2009, lake profiles were measured on Lake Clark, Naknek Lake, and Lake Brooks between the surface and 50 m for water temperature, pH, specific conductivity, dissolved oxygen, and water clarity. Water quality parameters were generally stable between sites throughout each lake except for water clarity. The spring eruptions of Mt. Redoubt and subsequent volcanic ash inputs into the Lake Clark system had a dramatic lake-wide effect on water clarity, greatly decreasing Secchi depth at all sites compared to 2008 observations. Continuous water temperature monitoring in Lake Clark has been ongoing since September 2006 while continuous temperature monitoring on Naknek Lake was initiated in August 2008. Water temperature data from both lakes depict temporary summer stratification followed by abrupt vertical mixing due to a strong wind events in late July. Water level and discharge measurements were continued on Naknek Lake and Lake Brooks in 2009. 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. Subsequent discharge measurements were used to refine rating curves. Continuous water quality and water level monitoring was conducted on Exit Creek during two-week deployment periods (late spring and mid-summer) to examine natural variation in water quality parameters due to diel glacial melting. Diel patterns were most obvious in water temperature and specific conductivity during low flow (spring / early summer) when ground water contributions to surface flow exceed runoff contributions comprising glacial and snowmelt runoff as well as precipitation events. Monitoring in 2010 will focus on applying all four aspects of freshwater flow system monitoring (lake profile monitoring, continuous water temperature monitoring, continuous water quality monitoring at select tributaries and outlets, and lake outlet level / discharge monitoring) on all four Tier 1 lake systems as well as incorporating lake profile monitoring on select Tier 2 lake systems.

Water quality and surface hydrology of freshwater flow systems in Southwest Alaska: 2009 annual summary report

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