Water Quality Monitoring, 2018 Annual Update

The Taiya River, part of Klondike Gold Rush National Historical Park, flows from high in the Coast Mountains to Taiya Inlet in northern Lynn Canal.

Water quality is an important and sensitive indicator of aquatic and terrestrial ecosystem health. Monitoring river and stream conditions helps scientists and park managers detect environmental patterns driven by human activity, climate change and watershed dynamics, then use that information to make better-informed decisions. The Southeast Alaska Inventory and Monitoring Network (SEAN) has prioritized continuous water quality monitoring in Glacier Bay National Park and Preserve, Sitka National Historical Park, and Klondike Gold Rush National Historical Park since 2010. Data collected thus far suggest good river health with episodic exceedances of Alaska Department of Environmental Conservation (ADEC) water quality standards.This research program (1) tracks hourly conditions at a single fixed site in each park from early spring to late fall, (2) examines seasonal and interannual variability, and (3) evaluates observations against state standards indicating optimal or hazardous conditions for fishes. Continuously collected data include:

• Water temperature (°C) reflects air temperature patterns and snow or glacial melt.
• Dissolved oxygen concentration (mg/L) quantifies microscopic oxygen bubbles essential to aquatic organisms. Mainly regulated by temperature, oxygen fluctuations can also be caused by enhanced biological respiration or decomposition, and water aeration.
• pH is a unit-less measure of hydrogen ion concentration indicating relative acidity or alkalinity. It affects freshwater species and many biogeochemical processes. The chemistry of local rocks, soils, and rain impact observed pH levels.
• Specific conductance (mS/cm) describes the ability of water to conduct an electrical current. In Southeast Alaska, higher values represent groundwater influence and lower values rain and snow runoff.
• Turbidity (NTU) measures water clarity due to sediment load; increases in turbidity typically signal precipitation events or glacial runoff, thus this metric is tracked at Klondike Gold Rush National Historical Park only.

2018 Southeast Alaska Weather Conditions

The region experienced exceptionally warm and dry conditions throughout summer and early fall 2018, with monthly temperature deviations from 0.5-1.8°C above the long-term average (Alaska Climate Center). A poor 2017-2018 winter snow season meant this natural reservoir provided less water in drier months. Near-normal precipitation in October and November was insufficient to compensate for the persistent drought. Weather conditions, particularly in the extreme, directly impact river water level and streamflow, as well as many water quality parameters.

Methods

During the ice-free season, water quality sondes sampled each river hourly at fixed locations. Once a month, park staff visited the site to check sensor calibrations, download data, and resolve any problems; this monitoring project would not be possible without their dedication and assistance. Sensor failures resulted in the loss of dissolved oxygen data for a small portion (11-26%) of the year at Glacier Bay and Klondike; Sitka pH values are likewise 55% missing. SEAN’s certified annual water quality data are publicly available, as is the peer-reviewed protocol guiding this monitoring program.

Daily mean water quality parameters for the Salmon River in 2018 (black lines) relative to the hourly measurements prior to 2018 (blue points). Bottom panel shows daily mean discharge rates (black lines) from the nearby stream gage and precipitation (blue bars) from the closest weather station.

Shaded regions denote ADEC thresholds for unsuitable fish habitat for temperature (above 13°C), dissolved oxygen (below 7 mg/L), and pH (below 6.5 or above 8.5).

Glacier Bay National Park and Preserve

Glacier Bay National Park and Preserve has more than 300 streams flowing over 3,380 km through a diversity of glacially shaped landscapes. The SEAN monitors the Salmon River, whose watershed primarily drains Excursion Ridge to the east and features mature wetlands and forests. This system is strongly groundwater influenced, reflecting greater transport and storage capacity in wetlands and the local aquifer. The sonde is located at river km 9.0, just upstream from the park boundary (map). Since 2014, a U.S. Geological Survey (USGS) streamflow gage has operated about one km downstream from the monitoring site; no significant tributaries exist between the two stations.

The Salmon River is home to many productive anadromous fish populations, such as pink, chum, and coho salmon, steelhead, cutthroat trout, and Dolly Varden. Although their life histories vary, especially with respect to spawning location and amount of time spent in the stream, all are vulnerable to environmental shifts due to climate processes. Tracking temporal changes in water temperature and flow patterns offers insight to these risks and is an established focus for Glacier Bay National Park and Preserve.

2018 Observations

• Water temperature followed a typical seasonal pattern, exhibiting a greater variability in fall than spring. Mean temperature 1 May - 31 October was above the 2010-2017 mean by 0.15°C. Peak summer conditions did not exceed the 13°C ADEC standard.
• Dissolved oxygen declined into the summer with warming water temperatures and low streamflow. Despite reaching some of the lowest recorded levels, oxygen remained within optimal ranges (above 7 mg/L) all year.
• pH was stable throughout all months, though lower than much of the historic record in spring and fall. Sharp drops in pH occurred during two rain events; values were always above the ADEC threshold of 6.5.
• Specific conductance is higher in the Salmon River compared to other sites, reflecting increased ion levels from wetlands and developed soils. It’s also more variable, with brief, steep declines during rain events.
• Discharge was generally low and steady due to both drought conditions and watershed storage. Persistent intervals of rainfall and storm events most strongly increased streamflow at this site, such as those in August and October 2018.

Salmon River freshwater data summary, 2018.

Parameter	n	Median	Mean	SD	Min	Max
Temperature (ºC)	5,791	6.92	6.92	2.71	0.53	12.60
DO concentration (mg/L)	5,285	10.08	10.27	1.36	7.02	14.56
pH	5,800	7.78	7.76	0.14	6.82	8.07
Specific conductance (mS/cm)	5,791	0.22	0.24	0.09	0.05	0.45
Discharge (NTU)	5,956	107.00	170.78	216.59	37.00	1,900.00

Daily mean water quality parameters for the Taiya River in 2018 (black lines) relative to the hourly measurements prior to 2018 (blue points). Bottom panel shows daily mean discharge rates (black lines) from the nearby stream gage and precipitation (blue bars) from the closest weather station.

Shaded regions denote ADEC thresholds for unsuitable fish habitat for pH (below 6.5 or above 8.5); Taiya River observations have not approached temperature (above 13°C) or dissolved oxygen (below 7 mg/L) thresholds.

Klondike Gold Rush National Historical Park

The Taiya River, located west of Skagway, is one of two major freshwater systems in Klondike Gold Rush National Historical Park. It drains a large mountainous watershed that was, as of 2010, approximately 29% covered by glaciers presently undergoing retreat. Glacial outburst events have caused large floods in the past and help shape this highly dynamic physical setting. The SEAN’s monitoring station is located near the Taiya River Bridge (map) adjacent to the long-established USGS streamflow gage. The Taiya watershed supports chum, pink, and coho salmon populations, as well as Dolly Varden and eulachon. Fish habitat conditions and turbidity fluctuations are particularly important to park natural resource managers.

2018 Observations

• Water temperature in the glacially influenced Taiya River is less responsive to seasonal changes in air temperature than other sites. Average temperature 1 May - 31 October was above the 2010-2017 mean by 0.24°C.
• Dissolved oxygen levels remained steady across all months, well within optimal fish habitat range (above 7 mg/L). The sharp late season increase was driven by abruptly colder water temperatures.
• pH was stable throughout the year, though consistently lower than the historic record. Readings were well above the ADEC threshold of 6.5.
• Specific conductance mirrored the typical seasonal shape (higher in spring/fall, lower summer) with shifts due to contribution from rainfall versus snow/ice melt. Overall magnitude of variability was low.
• Turbidity spiked most significantly during and after rain events, with lower magnitude increases associated with intervals of snow/ice melt. Extremely high turbidity values were not recorded in 2018.
• Discharge pulses in the spring and summer were tied to seasonal warming and melt processes as rainfall remained low (note their gentle shape compared to the sharp storm-driven spikes later in the year).

Taiya River freshwater data summary, 2018.

Parameter	n	Median	Mean	SD	Min	Max
Temperature (ºC)	4,691	5.45	5.28	1.60	-0.10	9.49
DO concentration (mg/L)	3,498	12.36	12.38	0.33	11.64	14.05
pH	4,691	7.23	7.2	0.19	6.75	7.56
Specific conductance (mS/cm)	4,691	0.04	0.04	0.01	0.02	0.08
Turbidity (NTU)	4,502	42.20	56.18	59.56	4.40	803.40
Discharge (cfs)	4,754	1,650.00	2,093.33	1,598.32	93.40	9,510.00

Daily mean water quality parameters for the Indian River in 2018 (black lines) relative to the hourly measurements prior to 2018 (blue points). Bottom panel shows daily mean discharge rates (black lines) from the nearby stream gage and precipitation (blue bars) from the closest weather station.

Shaded regions denote ADEC thresholds for unsuitable fish habitat for temperature (above 13°C), dissolved oxygen (below 7 mg/L), and pH (below 6.5 or above 8.5).

Sitka National Historical Park

The Indian River provides the only significant freshwater and estuarine habitat within Sitka National Historical Park. The 1-km section that flows through the park is a low-gradient channel supporting a diversity of anadromous and non-anadromous fish, including four species of salmon, steelhead, Dolly Varden, rainbow trout, three-spine stickleback, and coastrange sculpin. Quality of fish habitat, particularly during low flow and salmon spawning intervals, is a high resource management priority.

Draining a small, steep, and over 50% forested watershed, the Indian River is a mostly surface-water influenced system; discharge closely tracks precipitation events. Moderate development and human activity impact the lowest 2.5 km of the river. The National Park Service and City and Borough of Sitka collaboratively fund the USGS streamflow gage adjacent to the SEAN monitoring site (map), located just upstream of the park boundary.

2018 Observations

• Water temperature followed a typical seasonal pattern, with increased variability in the fall. Mean 2018 temperature 1 May - 31 October was above the 8-year average by 0.48°C. Peak summer conditions did not exceed the 13°C ADEC standard.
• Dissolved oxygen remained well above the ADEC threshold (7 mg/L) all year. Levels slowly but steadily declined over the summer (warmer water holds less dissolved oxygen) and increased with precipitation events and cooling in the fall.
• pH was stable throughout the months sampled and well above the ADEC threshold of 6.5. Slight dips were associated with rain-driven discharge pulses because the natural pH of Alaskan rainfall (~5.3) is less than that of the Indian River.
• Specific conductance dropped during intervals of precipitation but otherwise exhibited a low overall magnitude of variability.
• Discharge captured the dry spring and summer experienced across Southeast Alaska, followed by several large fall storms.
• In 2018, most parameters were monitored later into December than ever before.

Indian River freshwater data summary, 2018.

Parameter	n	Median	Mean	SD	Min	Max
Temperature (ºC)	5,528	7.74	7.66	1.41	4.36	11.83
DO concentration (mg/L)	5,523	12.09	11.98	0.59	10.07	13.14
pH	2,485	7.27	7.26	0.10	6.76	7.45
Specific conductance (mS/cm)	5,527	0.05	0.05	0.01	0.02	0.06
Discharge (cfs)	5,543	76.60	105.94	122.16	13.10	1,040.00

Suggested Citation

Goodwin, D. S., C. L. Amundson, and T. Ziomek. 2021. Southeast Alaska Network water quality monitoring program: 2018 annual update. National Park Service, Juneau, Alaska.

Principle Researchers: Deborah Goodwin, Courtney Amundson, Thomas Ziomek (contact us)

Data in this annual update were collected and analyzed using methods based on established, peer-reviewed protocols and were analyzed and interpreted within the guidelines of the protocols.