Southeast Alaska Network freshwater water quality monitoring program: 2016 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: • Monitoring the frequency and magnitude of hypoxic events in the Indian River in Sitka • 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 • Assessing whether state and federal water quality standards are met This seventh 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 2016, hourly water temperature, specific conductance, dissolved oxygen, and pH data were collected in the Salmon River (Glacier Bay) from April 20 through November 21, and in the Indian River (Sitka) from June 6 through November 21. The same parameters plus turbidity were collected in the Taiya River (Klondike Gold Rush) from April 8 through November 9. No observations signaled obvious point source pollution or a change to the fundamental water quality of the three rivers. Daily mean temperature for the Salmon River ranged from 1.8 to 12.3°C (peaking on July 24), while the Indian River ranged from 4.1 to 11.1°C (peaking on July 18). Daily mean temperature for the glacially influenced Taiya River ranged from 1.3 to 7.1°C and peaked on July 11. Taiya River hourly turbidity measurements ranged from 2.8 to 1,035 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 levels in the Indian River observed during summer 2013 were not observed in 2016. For the second year in a row during mid-September, the Taiya River sonde recorded a pH spike of 8.3 that persisted for several hours before dropping to more typical levels (long-term median = 7.4). Supporting data and environmental conditions during these periods were reviewed closely, and it is believed that the data are accurate, but the specific cause of the spike is unknown at this time and deserves closer consideration in future analyses.

Southeast Alaska Network freshwater water quality monitoring program: 2016 annual report

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