Fragile Waters of the Uinta Mountains
by Dennis Austin
Author Dennis Austin, a recently retired biologist for the Utah Division of Wildlife Resources, is a member of the High Uintas Preservation Council, an occasional contributor to this newsletter, and a resident of Hyrum. A version of this essay appeared in the June 11 edition of the Logan Herald Journal.
In the early 1960s one of my favorite lakes to camp on and fish, Heart Lake, maintained an abundant population of the tiger salamander. Unfortunately, in my last four visits to this lake since 1995, including last summer, I was unable to find any tiger salamanders. Also during the past 10 years, I have received reports from other backpackers indicating that lakes containing tiger salamanders in the 1950s, 1960s, or 1970s no longer maintained those populations.
Are these casual observed population changes of salamanders due to the naturally fluctuating environmental influences of chance, or are they due to air pollution and acid-rain causing changes in water chemistry? Could losses of aquatic organisms and fishes, as have been frequently observed in similar waters in Europe and eastern North America, occur in the Uinta Mountains? How real is the threat of acidified, fishless, and biologically dead lakes in the Uinta Mountains?
With increasing acidity, species diversity decreases at all tropic levels. Although numerous biological changes have been defined at levels of pH between 5. 7- 6. 9, the critical pH where significant change in aquatic biology becomes clearly evident is at pH 5. 6. At this level amphibians are mostly lost and fish losses are common.
For examples, cutthroat trout begin to die as alkalinity decreases toward zero, and pH declines below about 6. 0. The tiger salamander is very susceptible to changes in water chemistry and would likely be the first observed animals (amphibians are the most susceptible class) to succumb to the impacts of acid-rain at about pH 6. 5.
How are potential impacts from acid-rain estimated? Alkalinity is a measure of the buffering capacity in water that may be affected by acid-rain. Alkalinity is often used as an index to monitor potential changes in acidity of sensitive waters.
The Utah Division of Wildlife Resources measured alkalinity in the Uinta mountains between 1956 to the early 1990s on selected lakes. The results of those studies are alarming and showed alkalinity significantly declined from 33 mg/liter (milligrams per liter) in the mid 1950s - early 1960s, to 23 mg/l in the 1970s - early 1980s, to 17 mg/l in the mid 1980 - - early 1990s. (Great Basin Naturalist 56:167-171). By comparison most surface waters in Cache County measure in excess of 800 mg/l.
Decrease in alkalinity was particularly evident in the Provo and Duchesne River watersheds where the more complete data sets were available. In these two watersheds, 16 lakes were measured in each of the 3 sampling periods. Alkalinity decreased from 37 mg/l to 22 mg/l to 6 mg/l during the three periods! Since the early 1990s, according to Tom Pettingill of the Division of Wildlife Resources, broad-scale sampling of alkalinity in the lakes of the Uinta Mountains has been discontinued.
However, the U. S. Forest Service is continuing to measure alkalinity in the Uinta Mountains. to Ronnee Sue Helzner, hydrologist for the Ashley National Forest, the agency monitors water chemistry on selected and sensitive lakes on both an annual and intermittent sampling frequency depending on the lake and the previous year's sampling results. She also maintains a personal, keen interest, and reports a need to monitor air quality, the key to understanding the potential causes of changes in water chemistry in the Uinta Mountains.
Prior to summer 2004, I purchased a small alkalinity field test kit, identical to those previously used by the Division of Wildlife Resources in the Uinta Mountains. Last summer, while backpacking into the Granddaddy Lake Basin of the Rock Creek drainage, I carefully measured with repeated samples alkalinity at seven lakes: Granddaddy, Betsy, Heart, Lodgepole, Mohawk, and two unnamed lakes.
My results were concerning, but not alarming. In the seven lakes, alkalinity ranged from 8-15 mg/l. Fortunately, my results were similar to those of the Division of Wildlife Resources in the early 1990s.
My tentative conclusions: It appears the balance of acid-rain deposition from pollution versus natural deposition of buffers available in the Uinta Mountain geological deposits plus deposits from the prevailing winds across the Great Basin Desert has found a new, albeit lower, level of alkalinity and water chemistry equilibrium. Additional measurements at several lakes are needed annually to monitor potential changes in alkalinity and pH. Changes in the populations of the tiger salamander are questionable and may be unrelated to pollution, but populations should also continue to be monitored. Certainly decreases from pollution sources over the last 20 years in North Salt Lake City, Kennecott, Geneva, California, and from vehicle emission has aided in achieving this new balance.
Hopefully, with continued stringent controls over vehicle and industrial emissions, water chemistry in the fragile waters of the Uinta Mountains will remain the same or perhaps trend to improve to the levels measured in the 1950s and 1960s, and the High Uintas will remain a viable ecosystem of native plants and animals where "Earth and its community of life are untrammeled by man, where man himself is a visitor who does not remain."
To understand acid-rain, a simple review of water chemistry follows: Alkalinity is the measure of the concentration of cations (+), derived mostly from the presence calcium and magnesium in water. Cations are found in the soil and rocks in various concentrations and enter the aquatic ecosystem through natural runoff and erosion, and in the case of the Uintas, wind deposition of clay-sized particles from the Great Basin Desert. The presence of cations acts as a buffer to maintain water at the favorable pH of 7. 0 or higher. Unfortunately, the geologic rocks and soils found in the Uinta Mountains yield a minimum of cations.Anions (-), derived mostly from sulfur dioxide and nitric oxide, act as mild acids emitted from car emissions and industry, and cause acid-rain.