North Cascades Resource Brief Water Quality

Home , North Cascades, Ross Lake (Washington)

National Park Service North Cascades U.S. Department of the Interior Resource Brief North Cascades National Park Complex

Water Quality

The upper Skagit watershed spans the U.S./Canadian border and en- compasses 1,018 square miles (2,637 square km). Over the past ten years, an average of 302,940 people a year visit the Ross Lake NRA. This area supports a renowned Rainbow Trout fishery, and it is also home to one of the most protected and robust populations of Bull Trout in the lower United States. These factors combine to make the upper Skagit a unique area supporting exceptional recreational fishing opportunities and the conservation of a Federally Threatened species.

While the majority of the land in the Lake (Figures 1 and 2). Each of these watershed is protected as Park Lands or stations has been continuously monitor- Wilderness Areas, the aquatic resources ing water temperature at the surface, in this area still face threats from past mid-depth and near the bottom of the and current land-use practices, climate lake since that time. In addition to tem- change, as well as the atmospheric perature, water chemistry, chlorophyll-a deposition and run-off of pollutants. and zooplankton samples are collected To assess the impacts of these stressors at Pumpkin Mountain, Skymo and Little and guide management activities, North Beaver during the height of biological Cascades National Park, with support productivity from April through Novem- from the Skagit Environmental Endow- ber. The information generated from ment Commission (SEEC) and Seattle these activities will be used to assess City Light (SCL), is monitoring the water nutrient availability, acid neutralizing quality and ecological conditions of Ross capacity, trophic status and the ecologi- Lake and six of the major tributaries in cal condition of the lake. All field opera- the watershed. tions, laboratory procedures and analysis techniques follow the guidance outlined Monitoring Ross Lake in the North Coast and Cascade Net- Objectives work Water Quality Monitoring Protocol 1. Assess the current water quality condi- developed as part of the NPS’s Inventory tions and determine the trophic status of and Monitoring Program. Ross Lake. 2. Characterize the seasonal variation 2011 Activities of the water quality conditions in Ross This is the third year of data collection Lake. for SEEC’s Ross Lake water quality 3. Develop a context for interpreting monitoring project. The commitment to how the ecological integrity of Ross Lake long-term monitoring is beginning to pay is responding to fluctuations in nutrients off as our understanding of Ross Lake’s levels, the atmospheric deposition and seasonal cycles increases. run-off of pollutants, climate change and introduced non-native species. At this time, we have received laboratory 4. Determine and verify the long-term results for most of the 2010 water chemistry and zooplankton samples. These Figure 1. Rawhouser measuring water trends in the water quality and trophic quality on Ross Lake. status of Ross Lake. results have enabled us to make a preliminary assessment of the trophic status Summary of Activities of the reservoir. Temperature data are Contact: In May 2009, four water quality monitor- downloaded annually in November, and [email protected] ing stations were established at equally this year we will have forty-one months [email protected] spaced locations along the length of Ross of continuous temperature data. Figure 2. Locations of water quality One of the primary concerns that initi- monitoring stations in Ross Lake. ated the assessment of water quality in Ross Lake was that the availability of nutrients was decreasing as the reservoir aged. The primary evidence for this came from fish population surveys conducted by the Washington Department of Fish and Wildlife. The surveys conducted prior to 2009 indicated that fish size had decreased in the incidence of parasites had increased over time.

Phosphorous in lakes is often the limit- ing factor in lake productivity. Lakes Figure 4. Photographs of Aphanocapsa and Aphanothece found in samples col- are considered ultra-oligotrophic, or lected from Ross Lake. (Photo Credit: Robin nutrient poor, with total phosphorous Mathews) (TP) concentrations <5 µg/L and oligo-

trophic with concentrations of 5 to 10 tributed 70, 24 and 6% of the organisms, µg/L. Oligotrophic lakes are considered respectively. to be optimum for supporting salmonid fisheries. Results from the zooplankton tows provided some of the most interesting Since the TP concentrations in Ross insights into the condition of Ross Lake. Lake ranged as high as 8 µg/L it appears The zooplankton samples collected that the decrease in fish health may have for this project used a 64-µm mesh net. been unrelated to lake nutrient levels. This mesh size was selected because it Preliminary Results and Discussion is small enough to capture the largest These results should be considered pre- Secchi disc transparency (SDT) mea- zooplankton while allowing the smaller, liminary and are not meant to be widely surements deeper than 8 m also indicate often single-celled organisms and phy- distributed. Our intent is to provide oligotrophy, and the mean SDT for Ross toplankton; to pass through. However, SEEC with a set of initial findings and Lake was 12.6 m. Dissolved oxygen was the samples collected in 2009 were filled to keep the commission updated on the diffused equally throughout the water with an unusually dense algae bloom activities of this project. column with a mean concentration of 9.5 that developed in the summer of 2009

mg/L. While water temperatures are a and 2010, and this bloom clogged the Water Temperature concern, these results indicate that Ross collection net and lab equipment used to Surface water temperatures were much Lake is oligotrophic and capable of sup- process the samples. To help determine warmer than anticipated. All of the sur- porting healthy native fish populations. the source of the clogging supplemen- face water temperature stations regularly Laboratory results from the 2011 field tal plankton tows were collected and recorded daily maximum temperatures season will augment the current data set sent to Dr. Robin Matthews at Western above 20°C in July and August. The and provide a more complete picture of Washington University for analysis. regulatory criteria for water temperature seasonal variations. Initial results indicate that the source of is measured as the seven-day average of the clogging is likely coming from two the daily maximum temperature. Water Zooplankton genera of cyanobacteria (blue-green temperatures above 12°C for this criteria A total of 40 unique taxa were collected algae): referred to as Aphanocapsa and are considered too warm to support from the three stations in Ross Lake. Aphanothece (Figure 4). At this time, the rearing habitat for native char. While Rotifers, cladocera and copepods con- the epilimnion would not generally be expected to provide abundant cold water habitat in the summer, it does appear that temperature may be more of a limit- ing factor for native char populations than previously thought. We found that water temperatures from late May into November exceeded the 12°C regulatory threshold, and it appears that the majority of the cold water habitat is found in water deeper than 20 m during this time (Figure 3). Figure 3. Plot of continuous temperature data from the Big Beaver water quality station for the seven day average of the daily maximum temperature. Water Chemistry implications of these taxa on the water quality in Ross Lake is uncertain and 2011 Field Sampling zooplankton samples collected in 2011 All six of Ross Lake’s major tribu- did not appear to have the same concen- taries were sampled in September trations of Aphanocapsa and Aphano- thece as the previous two years. of 2011, and all temperature stations yielded information provided. Monitoring Ross Lake Tributaries Water and air temperature data Project Objectives were downloaded from all temperature stations, and data loggers 1. Determine status and trends of Figure 6. Little Beaver Creek was visited the water quality and ecological were replaced. Temperature station and sampled for three consecutive years. integrity for the major tributaries hardware was checked and replaced draining into Ross Lake. as necessary. All contracted analyses and data 2. Identify specific land manage- Four benthic macroinvertebrate concerning 2010 Ross Lake tribu- ment activities affecting the water samples were collected from riffle tary samples have been completed quality of the streams draining into habitats in each of the six tributar- and received. Processing and evalu- Ross Lake. ies. These samples will be used to ation of 2011 data is ongoing. Ben- assess the ecological integrity of the thic macroinvertebrate samples are Objectives for 2011 tributaries being monitored. currently being processed by the 1. Conduct annual monitoring contracted lab. Data are expected at each sample location to collect Data characterizing in-stream early in 2012. benthic macroinvertebrate samples, conditions and riparian habitat download continuous water and air were collected for all six tributary Notes of Interest temperature data, conduct mainte- sites. Water quality parameters col- The USFS completed the removal nance of air and water temperature lected at all six tributaries include: and capping of contaminated mine stations and collect water chemis- pH, DO, conductivity, water clar- tailings as part of the Azurite Mine try samples. ity, water odor, sediment odor and CERCLA cleanup. USFS will con- surface films. tinue monitoring stream sediments 2. Validate and enter data collected and water quality at the cleanup site during 2011. Implement standard Data Management into the foreseeable future. quality control practices. Process Continuous temperature data were and evaluate data, comparing it to validated and an initial evaluation Major construction was conducted previous results to identify changes has been conducted. Data loggers in Cabinet Creek on USFS lands and assess trends. were tested for post-deployment to stabilize Highway 20. During calibration and for quality control construction, Cabinet Creek was Summary of 2011 Activities purposes. diverted and the entire stream channel was cleared below the road to Ruby Creek.

SEEC-funded monitoring will play an important role to determine if these activities are impacting Ruby and Canyon Creeks.

Figure 5. A comparison of maximum 7-day average temperature for all six tributaries monitored as part of the SEEC water quality project. Water temperatures exceeding 12°C exceed Washington State regulatory criteria for supporting native char rearing habitat.