Part 2 of a series on Utah Lake. The following observations and insights concerning Utah Lake have been developed during my nearly 50 years in Utah Valley as a professor, researcher, environmental engineer, consultant, and local citizen.
To many people, water quality and pollution are in the eye of the beholder—literally, how does it look? A more reasoned definition might be “presence of human-caused constituents that interfere with a desired use.” But even this rather broad view does little to pinpoint what pollution and quality problems might be present. As to water quality—organic debris, suspended particles, dissolved salts, microbial pathogens, nutrients, heavy metals, other natural and manufactured chemicals, radioactive matter, and heat address most pollution categories. But if one broadens it to a waters ecosystem, many other aspects come into play.
Considering the lake’s basin-bottom location and natural eutrophic nature, its overall water quality is good. However, the lake was not, is not, and cannot be a “clear” lake, due to its inherent nature of very high biological productivity, large natural mineral precipitation, and frequent wave-stirred nature.
Hydrologic and water quality studies indicate that overall lake water quality has changed very little over the last 60 years and in some parameters it has significantly improved. Remember that prior to about 1955, most sewage, storm runoff, and industrial wastes received little, if any, retention or treatment before being dumped into the lake.
A common “quality” problem in eutrophic lakes is oxygen depletion which can cause a litany of water quality and habitat problems. However, Utah Lake is largely devoid of these problems since it is rather shallow and is frequently stirred by wave action. Under these conditions oxygen is rapidly renewed and the lake largely avoids serious oxygen depletion and the septic conditions that often plague other productive lakes. In addition its abundant calcium and magnesium, high pH, and high oxygen levels generate very favorable conditions for organic debris degradation and dissolved salt precipitation. This results in precipitation of most of the heavy metals and phosphorus to the bottom sediments. For example, Geneva Steel discharged considerable amounts of heavy metals into the lake during the 1940s to 1990s, but water sampling seldom found significantly higher heavy metal concentration levels in the vicinity of discharge points than background levels throughout the lake.
Nutrients (Phosphorus and Nitrogen) in Utah Lake
Currently, increased attention is being given to nutrient enrichment of the nation’s waters. The nutrient issue exists since in many cases nutrient enrichment results in excessive aquatic plant growth that causes environmental and water quality problems. However, programs to address nutrient enrichment tend to generate hot controversy primarily for two reasons: uncertainty and cost.
- Uncertainty: Phosphorus and/or nitrogen are only two of many factors that determine the amount of aquatic plant growth. Other factors are the amount of light, temperature, other trace nutrients, toxicants, and variation in factors over time. It’s very difficult to pinpoint which of these is controlling growth at a given time and over time.
- Costs: Management steps and treatment processes to control or remove nutrients are usually very disruptive and costly. These reasons related to Utah Lake will be explored in more depth in a later article.
Large amounts of nutrients flow into Utah Lake—10 to 15 times the amounts necessary to support large, persistent algal blooms. Concentrations of phosphorus in waters flowing into the lake are not directly toxic to aquatic organisms or to man. The same is true for nitrogen, although one might find some ammonia toxicity for aquatic organisms near some wastewater discharges. One might be initially alarmed by such high nutrient loadings, thinking they must certainly doom the lake to massive algae growth and widespread quality problems. However, scrutiny of the lake’s chemical characteristics and algae-growth dynamics indicates that the large nutrient loading is likely a moot point since it appears that algal growth is usually light-limited due to the lake’s natural turbidity. In addition, natural chemical-reaction equilibria usually reduce available phosphorus to relatively low levels.
In Utah Lake occasional blue-green algae (actually cyanobacteria) blooms occur and may become a problem since some contain toxins. These occur naturally and it is doubtful that they are more frequent and intensive now than in the past. The conditions that exacerbate these blooms are:
- Calm weather conditions that persist for several days or more, allowing the water to clear and also cause the water to become warmer.
- Adequate amounts of phosphorus and nitrogen but relatively more phosphorus. As the bloom proceeds nitrogen is largely depleted. This favors the nitrogen-fixing blue-green algae.
As conditions change the bloom dies away, algal cells lyse, and toxins are released into the water that may temporarily reach levels of concern—possibly toxic to some of the other aquatic life or to terrestrial animals that ingest the water.
In summary, the large nutrient loadings to the lake are likely a minor factor as to its overall water quality, since growth-limiting natural turbidity is widespread and persistent. Also, chemically binding reactions and precipitation of phosphorus are also in play to make phosphorus limiting at times, but even then the concentrations of available phosphorus in the water are dependent on the equilibrium chemistry, and very little on the amount of phosphorus coming into the lake.
Of course, constant vigilance is needed to avoid serious lake pollution problems. For many exotic pollutants of concern in our nation today, cleanup and restoration are typically monumentally more costly than initial costs for proper waste disposal and pollution prevention. Since the lake is downstream of many human activities in Utah Valley, too frequently tributaries are illegally used as convenient dumps for refuse that sometimes contains nasty polluting materials, some of which are carried into the lake.
Did Pollution Kill the Lake’s Bonneville Trout?
Bonneville Cutthroat trout were abundant in pioneer times and common in Utah Lake until about 1900. This Cutthroat was a large fish, with many weighing more than 10 pounds. It doesn’t appear that “pollution,” as we normally consider it, caused their demise. Rather, overfishing, competition from introduced fish species, and interferences with stream spawning and migration cycles caused by dams and irrigation diversions resulted in low trout numbers after about 1900. Intensified stresses hit the greatly reduced Bonneville Cutthroat population during the 1930s drought when fish struggled to survive in extremely low levels of warmer and warmer water in both the lake and its tributaries. These combined stress factors eliminated the Bonneville Cutthroat from the lake by the 1940s. Similar ecological factors continue to challenge other remaining native species in the lake, notably the endangered June Sucker.
Re-establishment of large numbers of trout in Utah Lake is unlikely—it would require major changes in other fish species now in the lake and a large hatchery-based stocking program to maintain good populations. Remember, however, that the lake has very large populations of other fish in this prolific warm-water fishery. Overall, Utah Lake’s fishery is greatly underused. Two of its species, Carp and Catfish, are under a limited-consumption advisory due to PCB concerns, but most knowledgeable people have no concerns in eating these fish unless they are a very frequent part of one’s diet.
June Suckers are currently listed as an endangered species under the Federal Endangered Species Act, therefore continuing efforts to protect and restore them are major driving factors in lake management. However, it appears that lack of favorable spawning and brood habitat and species competition, not water quality, are the main determinants in recovering to non-endangered status. Some experts and many other observers question the long-term wisdom and economic feasibility of efforts to “re-balance” species and altered ecosystems. Questions as to our ability to actually accomplish the hoped-for results, the value of these results, and large costs often associated with trying to achieve restoration-preservation goals, give rise to serious value and cost-benefit issues. This is the case in Utah Lake where many people feel these issues should be more openly and critically debated and considered before additional tens of millions of dollars are spend on attempts to restore this endangered species. Sometimes ongoing external funding and local vesting in the effort combine to push detractors into a “politically incorrect” corner from where they find it difficult to raise feasibility and cost issues, or to generate balanced, serious discussion on them. Hopefully all sides will strive for opportunities to discuss and debate these and similar issues, without extraneous intimidation.
The Invasive Plant—Phragmites
A foreign, invasive water plant, Phragmites, has become a huge problem in the ecology of Utah Lake. Some 20 years ago, it was introduced into the lake by an unknown carrier; it has spread throughout most of the lake’s shallows. Phragmites is a tall reed plant that chokes out other aquatic plant life and its debris fills in shallows rather rapidly, thus damaging and reducing aquatic habitat. This exotic plant grows prolifically in shallows along the shoreline and even on adjacent wet-flats. When uncontrolled, it crowds out nearly all other aquatic plants and forms an almost impenetrable mass of growth. It does great damage to a lake ecosystem. Initially, it grew mainly in the Saratoga Springs area (northwest corner) of the lake but it is now found essentially around the entire lake. Trial efforts have been underway for several years to develop control techniques and plans; “elimination” is very difficult and unlikely. Utah County Weed Control personnel have energetically attacked Phragmites the past few years and are adapting control methodologies that promise success, but they need the resources to continue control programs in a rigorous and persistent manner year after year or else Phragmites will become entrenched as a major disaster to the lake’s natural ecosystem.
The Quagga Mussel
The Quagga mussel is a fairly small freshwater mussel, with sharp-edged shells, that has become a “pest” in many fresh waters. To grow prolifically, it needs a solid substrate (rock, large gravel, concrete, pipes, etc.) to attach to, and “currents” in the water to continuously bring food to it. To date this pest mussel has not been found in Utah Lake, although in 2014 it was found upstream in Deer Creek reservoir on the Provo River. It is not known whether conditions in Utah Lake, that generally seem unfavorable to it, might support nuisance levels of Quagga mussel growth if it gets into Utah Lake—hopefully it is a minor threat to Utah Lake due to the relative lack of “rocky” substrate and persistent water currents to carry food to the mussel.