The Southwest Alaska Network (SWAN) monitors freshwater systems in five national park units: Alagnak Wild River (ALAG), Aniakchak National Monument and Preserve (ANIA), Katmai National Park and Preserve (KATM), Kenai Fjords National Park (KEFJ), and Lake Clark National Park and Preserve (LACL). The metadata included in this file supplement water quality data from vertical lake profiles taken between 2008 and 2023 in KATM, LACL, and KEFJ. Vertical lake profile sampling was initiated in high priority “Tier 1” lakes in LACL in 2008 and expanded to other parks and lakes in subsequent years. At present, there are 105 total sites. Of the 31 Tier 1 sites in LACL, there are ten sites in each of three basins of Lake Clark and one on Kijik Lake. Of the 41 Tier 1 sites in KATM, there are ten sites at each of four basins of Naknek Lake and one on Lake Brooks. There are 33 lower priority “Tier 2” sites: 15 in LACL, 16 in KATM, and two in KEFJ. Tier 1 lakes are sampled annually in LACL and KATM, while Tier 2 lakes are sampled less frequently on a rotating basis.

Vertical lake profiles are taken during the mid-summer index period when thermal stratification is most pronounced. Profiles are conducted using a water quality meter (or “sonde”) that simultaneously records multiple parameters: temperature, pH, dissolved oxygen, specific conductivity, and, beginning in 2014, turbidity. Sampling is conducted at 15 depth categories to a maximum depth of 50 m. Specifically, data are recorded at every meter from 0 to 5 m depth, and then at 5 m increments between 5 m and 50 m or the lake bottom, whichever is reached first. This method creates a vertical profile of each water quality parameter at each site. Additional measures of water clarity via Secchi disk are made in conjunction with each vertical lake profile. Other metadata include specifics about personnel, location, timing, equipment, and weather.

The vertical lake profile data that accompany the metadata in this file can be accessed and downloaded from the public AQUARIUS Water Data Portal (https://irma.nps.gov/aqwebportal/).