Deer Creek Reservoir Water Quality Improves

The drinking water supply for nearly one million people requires higher quality standards.

LeRoy W. Hooton, Jr.

March 2, 2001

According to EPA, nutrients flowing into lakes, reservoirs and ponds are the number one pollutant affecting water quality. Excessive nutrients cause overgrowth of algae that leads to the depletion of oxygen from microbial decomposition of plant matter. A severe case of oxygen depletion causes “eutrophication,” a condition that renders the water incapable of supporting aquatic life. Nitrogen and phosphorus are the leading pollutants causing problems in lakes and reservoirs. Agriculture produces 79 percent of the pollution, according to EPA. Certain algae cause taste and odors in drinking water supplies, and this is a major concern of municipal water suppliers who use stored water in lakes and reservoirs.

Nutrient Loading in Deer Creek Reservoir

Deer Creek Reservoir looking west towards the dam. Completed in 1941, the project provides irrigation and municipal water supply.

Built by the Bureau of Reclamation in the late 1930s, Deer Creek Reservoir, located 38-miles from Salt Lake City, is a major source of drinking water supply for nearly one million people along the Wasatch Front. This body of water was not immune from the impacts of excessive nutrient loadings. In 1981, because of concern over eutrophication, Utah Governor Scott Matheson formed the Jordanelle Reservoir Water Quality Technical Advisory Committee (JTAC) to develop a reservoir management plan for Deer Creek Reservoir and the yet to be constructed Jordanelle Reservoir. In 1984 JTAC implemented a Water Quality Management Plan for the two reservoirs.

Tests showed phosphorus was the primary source of pollution coming from a variety of natural and manmade sources within the 248,000-acre watershed. Agriculture, urban run-off and recreational activities all contribute to the problem. Programs and studies have been implemented to abate the problem. In 1998, JTAC took nearly 600 samples from 46 locations in streams and reservoirs. Reservoir sampling is accomplished at different depths of water.

According to the 1999 Water Quality Implementation Report, 1998 sampling data show that Deer Creek Reservoir is healthy; however, according to the Report, “...based on dissolved oxygen data, there is need for additional improvement.”

Trophic State Index (TSI) is a comparative index for determining the condition of a lake. It ranks lakes as eutrophic (high nutrient level); mesotrophic (healthly nutrient level); and oligotrophic (low nutrient level). Deer Creek reservoir is mesotrophic.

Keith Denos, general manager of the Provo River Water Users Association (PRWUA), shares the view that water quality has improved. “Deer Creek water quality has greatly improved during the 6 years that I’ve been general manager,” says Denos. “JTAC and Wasatch County have made significant improvements to the watershed, particularly in the middle Provo River through the Heber Valley.” According to Denos, their focus has been to work with farmers and ranchers to prevent nutrient loading from agriculture and feedlot run-off.

Taste and Odor Algae Blooms

Even though the nutrient loading in Deer Creek Reservoir is trending downward, algae blooms that cause taste and odors in drinking water still exist. During January and February 2001, a number of taste and odor complaints were received from Salt Lake County residents. According to Denos, the taste and odor problem was traced to the water coming from Deer Creek Reservoir. Water experts identified the problem with the chemical geosmin, a substance known to cause taste and odor complaints. Samples indicated a level of 11 to 44 ng/l of geosmin from the Deer Creek Reservoir; however, the Provo River downstream from Deer Creek Reservoir did not show similar concentrations. Humans can detect levels over 4ng/l.

The Metropolitan Water District of Salt Lake & Sandy began treatment with activated carbon to remove the taste and odor constituents. Areas receiving undiluted water appeared to generate more complaints than did the areas that were blending with other water sources. The cause of the problem appears to be in Deer Creek itself. Last fall algae identified as phytoplankton genera were blooming as the reservoir froze over. These algae are known to cause taste and odor problems. The exact organism responsible for this incident is not known; however, reservoir turnover did contribute to the incident.

Recreational activities can likewise cause pollution. PRWUA, in cooperation with the Bureau of Reclamation and State Division of Parks, have implemented pollution control measures around Deer Creek Reservoir. Parking vehicles, fueling activities and domestic animals are now prohibited on the beaches or in the water. Deer Creek Reservoir is a popular recreation area for thousands of users. Boating, fishing and camping are recreational activities permitted on and around the 152,000 acre-foot reservoir. In the year 2000, over 200,000 visitor days were spent at the reservoir site. In 1999 the State Parks continued with the second phase of a $5.5 million renovation project, including new restroom facilities, that will help in the sanitation needs of the site.

Emerging Pathogens Concerns

Over 200,000 recreational visitors used Deer Creek Reservoir in the year 2000.

Florence Reynolds, Water Treatment and Water Quality Administrator for Salt Lake City Department of Public Utilities, along with health scientists and water mangers are becoming more concerned with new pathogens in drinking water. According to Reynolds, the high recreational use of Deer Creek Reservoir raises concerns over the microbial content of the impounded water. "As recreational popularity of the reservoir increases due to population growth along the Wasatch Front, the potential for microbial contamination increases," says Reynolds. Data collected on the Provo River in 1998 shows seasonal variations in Giardia and Cryptosporidium counts above and below the reservoir. "It's not certain that these organisms are present in great numbers in the reservoir," Reynolds notes. "But these preliminary counts need to be followed up to determine if there is a significant source of oocysts coming into the reservoir that can be controlled."

Microbial concerns also increase with new regulations. The UCMR (Unregulated Contaminants Monitoring Rule) lists several microbial contaminants in Tier III. Aeromonas, Heliobactor, Microsporidium, some algae and their toxins are included, among others, being considered for regulation by this rule. High usage with the associated potential for contamination of the water resources leaves the facility at risk for higher microbial counts.

Challenges in Balancing Clean Water and Recreation Opportunities

As JTAC continues its efforts to reduce the level of nutrient pollution entering the tributary streams and Deer Creek Reservoir, a new emphasis on microbial pollution is emerging. Driven by growing population and recreational demands on the one hand, and on the other hand the need for safe drinking water, water quality in Deer Creek will become ever more important to the citizens along the Wasatch Front.

Many people don’t connect the need to balance recreation activities with clean water. Recreational interests understand the need for clean water in the pursuit of recreational opportunities, but sometimes fail to understand their impact on clean water. A report entitled "Reservoirs of Opportunity," authorized by Congress, points out the growing pressure for recreational opportunities on federal lakes. The National Recreation Lakes Study Commission, June 1999 report sides with clean water. "Clean water is critical to lake recreation as well as lake health. The commission endorses the total watershed approach to clean water and the EPA's expressed commitment to give increased emphasis to clean lakes under the Clean Water Act." However, the report also points out the unintentional impact of growing recreation activities. "By the hundreds of thousands, people flock to their waters, their shores, their adjacent parks, and their tailwaters downstream. Federal lakes are a canvas of boating, camping, swimming, fishing, hiking, and other leisure pursuits." The marriage of clean water and recreational activities will be the challenge facing both local water officials and the recreational community in the multiple uses of reservoirs.