Southeast Alaska Network freshwater water quality monitoring program: 2015 annual report

Sergeant, Christopher; Johnson, William

Freshwater water quality is an indicator of aquatic and terrestrial ecosystem health and one of twelve priority Vital Signs in the National Park Service’s Southeast Alaska Network (SEAN), which includes Glacier Bay National Park and Preserve, Klondike Gold Rush National Historical Park, and Sitka National Historical Park. Data collected under this program inform several management-relevant topics: • Assessing whether state and federal water quality standards are met • Measuring the natural quality of wilderness lands in Glacier Bay • Describing effects of a changing climate on the physical and chemical properties of park waters (For example, how do changes in glacial watershed coverage, wetland water filling patterns, or forest cover affect long-term water quality patterns?) This sixth annual report is intended to be a concise data summary and regular product for park staff, managers, superintendents, and other interested parties. All annual reports and data products are publicly available at the SEAN website: http://science.nature.nps.gov/im/units/sean/FQ_Main.aspx In 2015, hourly water temperature, specific conductance, dissolved oxygen, and pH data were collected in the Salmon River (Glacier Bay) from April 23 through December 2, and in the Indian River (Sitka) from April 27 through November 19. The same parameters plus turbidity were collected in the Taiya River (Klondike Gold Rush) from April 6 through November 19. No observations signaled obvious point source pollution or a change to the fundamental water quality of the three rivers. Water temperatures collected in 2015 from April through July were generally warmer than previous monitoring years 2010 through 2014, but not of concern. Daily mean temperature for the Salmon River ranged from 2.6 to 12.2°C, while the Indian River ranged from 5.1 to 11.2°C. Both rivers peaked in temperature on August 18. Daily mean temperature for the glacially influenced Taiya River ranged from 0.7 to 7.3°C and peaked on June 14 and August 18. Taiya River hourly turbidity measurements ranged from 0 to greater than 1,000 NTU and were synchronized with high flow events. Patterns in the medians and distributions of specific conductance, dissolved oxygen, and pH were generally similar to previously observed ranges for all three rivers. The critically low dissolved oxygen conditions of the Indian River observed during summer 2013 were not observed in 2015. On September 10, the Taiya River sonde recorded a pH spike of 8.8 (increase of 1.4 units) that persisted for several hours before dropping to more typical levels. Supporting data and environmental conditions during this period were reviewed closely, and it is believed that the data are accurate, but the specific cause of the spike is unknown at this time.

Southeast Alaska Network freshwater water quality monitoring program: 2015 annual report

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