Southeast Alaska Network freshwater water quality monitoring program: 2011 annual report

Sergeant, Christopher; Johnson, William; Moynahn, Brenden

Freshwater water quality is an indicator of ecosystem health and one of twelve priority Vital Signs monitored in the National Park Service’s Southeast Alaska Network (SEAN). In 2011, hourly water temperature, conductivity, dissolved oxygen, and pH data were collected in the Salmon River (GLBA) from May 31 through September 30, and in the Indian River (SITK) from June 28 through September 27. The same parameters plus turbidity were collected in the Taiya River (KLGO) from April 25 through July 25 and September 14 through November 14. In future years, data collection is planned to regularly occur from May 1 through October 31 as ice conditions allow. Annual reports are concise but thorough summaries of the previous season’s data that establish a regular product for park staff, managers, superintendents, and other interested parties. This is the second annual water quality report from the SEAN, representing the continuation of a sustained effort to collect long-term, high resolution water quality data in Southeast Alaska National Parks. This document analyzes the second year of data from GLBA and SITK, and the first year for the Taiya River at KLGO. All annual reports and data products are available at the SEAN freshwater water quality website: http://science.nature.nps.gov/im/units/sean/FQ_Main.aspx The Salmon and Indian Rivers demonstrated similar seasonal temperature trends to 2010. 2011 daily mean water temperature in the Salmon River ranged from 5.8 to 10.7°C, peaking on July 23, while daily mean water temperature in the Indian River ranged from 6.6 to 10.0°C, peaking on August 20. The Salmon and Indian Rivers have non-overlapping seasonal medians for conductivity, dissolved oxygen, and pH, but patterns within each river for these parameters were similar between 2010 and 2011 monitoring years. Due to the strong influence of glacial meltwater, the Taiya River demonstrated dynamic fluctuations in water temperature, especially May through July, and had a lower mediantemperature than the mostly ground- and surface-water influenced Salmon and Indian Rivers. In 2011, daily mean water temperature in the Taiya River ranged from 0.3 to 6.9°C, peaking on July13, with a median of 5.1°C. The ranges of seasonal values for conductivity, dissolved oxygen, and pH were quite small across the season. Turbidity was variable throughout 2011, ranging from 1.0 to 229.6 NTU, and was correlated with high flow events caused by heavy rain and glacial melt. During a warm/dry period on the Taiya River, median conductivity and pH values dropped slightly over time, while median water temperature and DO levels varied but did not demonstrate directional trends. During a cool/wet period water temperature dropped slightly and demonstrated less daily range than during the warm/dry period. Turbidity spikes during the cool/wet period were much greater than during the warm/dry period. Conductivity slowly rose, while DO and pH demonstrated little change. No observed values or trends appeared to signal point source pollution or a change to the fundamental water quality of the Salmon, Taiya, or Indian Rivers. Throughout the monitoring period, all three rivers exhibited water quality conditions within expected ranges.

Southeast Alaska Network freshwater water quality monitoring program: 2011 annual report

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