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Water: Total Maximum Daily Loads (303d)

Total Maximum Daily Loads (TMDLs) at Work: Utah

Building on Past Implementation Success in the Deer Creek Reservoir

Using the TMDL Process to Maintain and Protect Water Quality

What is a total maximum daily load (TMDL)?

It is a study or analysis that calculates the maximum amount of a pollutant that a waterbody can receive and still meet water quality standards. The TMDL establishes a pollutant budget and then allocates portions of the overall budget to the pollutant's sources. For more information on TMDLs, visit EPA's Impaired Waters and Total Maximum Daily Loads Web site.

TMDL at a Glance:
Factors causing impairmentColdwater aquatic life use impaired by low dissolved oxygen levels at the bottom of the reservoir caused by excessive phosphorus loads and high surface water temperatures that affect the reservoir's fisheries
Sources contributing to impairment Nonpoint source runoff from urban areas and agricultural activities; a fish hatchery
Restoration options Implement agricultural best management practices, cleanup potential concentrated animal feeding operations, streambank restoration, load reduction from fish hatchery, and develop comprehensive nutrient management plans for feedlots casing water quality impairments
Stakeholder involvement Wasatch, Salt Lake, and Utah counties, Midway Fish Hatchery, Jordanelle Reservoir Water Quality Technical Advisory Committee, five regional conservancy districts, Utah Department of Environmental Quality
Status of waterbody Met annual phosphorus load reductions established by the TMDL to allow for future growth and a margin of safety during 2006 and 2007; mixed success in meeting other endpoints established by the TMDL to maintain good water quality
Benefits to stakeholders Clean water, recreation, aesthetics, economy, funding, partnerships and education
Approved TMDL document Deer Creek Reservoir Total Phosphorus (approved September 2002) (PDF) (92pp, 5.1MB, about PDF)

Printable Versions

"Sound byte" Version of Story (PDF) (2pp, 248K, about PDF)


"Technical" Version of Story (PDF) (5pp, 319K, about PDF)


In 1941, the Bureau of Reclamation completed construction of the Deer Creek Reservoir, located on the Provo River in Wasatch County, Utah. Since that time, Deer Creek Reservoir has become a vital source of drinking water for over one million people, as well as a source of irrigation water and a popular recreation destination. In the 1980s, concerns over excessive nutrients in Deer Creek Reservoir led to the formation of the Jordanelle Reservoir Water Quality Technical Advisory Committee (JTAC), the group responsible for the development of a water quality management plan for Deer Creek and Jordanelle reservoirs. Although Deer Creek Reservoir at one time did not support the coldwater fishery beneficial use due to low dissolved oxygen (DO) levels and high temperatures, analysis of recent data from Deer Creek Reservoir through the TMDL process revealed that stakeholder efforts led to significant improvements in both water quality and the health of the reservoir's fishery. Despite these improvements, the TMDL analysis revealed that DO levels remained a concern under certain conditions. Too much phosphorus beyond the current loads could lead to algal blooms that would affect the quality of the drinking water supply and require costly treatment. As a result, the TMDL for Deer Creek Reservoir established quantifiable targets to maintain current water quality and identified phosphorus reductions to provide a margin of safety and allow for future growth in the watershed.

How are TMDLs at work in the Deer Creek Reservoir?

The TMDL process provided stakeholders with a framework for compiling, analyzing, and understanding data for parameters affecting DO levels in the Deer Creek Reservoir. The data analysis of factors contributing to the coldwater fishery beneficial use impairment identified for Deer Creek Reservoir, including dissolved oxygen levels, temperature, algae levels, water clarity, and fishery health, all showed signs of improvement at the time of TMDL development. These improvements are attributed to years of water quality improvement projects and programs. Although the TMDL development process did reveal improvements in water quality, it also highlighted the sensitivities of Deer Creek Reservoir. The final TMDL report states that although major improvements are not needed, it is important to have a plan in place that stresses protection and management of current conditions-particularly in light of growth and development pressures in Wasatch County. As a result, stakeholders were able to participate in the development of a TMDL that establishes quantifiable goals to maintain current phosphorus loads and identifies phosphorus reductions necessary to maintain a margin of safety and allow for future growth. The TMDL report estimates that nine restoration projects, implemented by local, state, and federal partners, will generate approximately 2,965 kilograms per year (kg/yr) in phosphorus reductions at a cost of approximately $38,100,000. The TMDL report estimates that these projects, implemented by local, state, and federal partners, will generate approximately 2,965 kg/yr in phosphorus reductions at a cost of approximately $38,100,000.

What is the current status of Deer Creek Reservoir as a result of the TMDL process?

The 2008 Water Quality Implementation Report for the Provo River, Jordanelle Reservoir, and the Deer Creek Reservoir, prepared for the Provo Watershed Council, provide a summary of the data collected during the 2006 and 2007 water years. Table 1 provides a summary of an assessment of progress in Deer Creek Reservoir during 2006 and 2007 using the endpoints established through the TMDL development process as a yardstick.

According to the 2006 and 2007 data, annual phosphorus loads to Deer Creek Reservoir were below the 15,300 kg/ yr total load allocation (i.e., current and future allocations to point sources and nonpoint sources) established in the TMDL. However, monthly phosphorus loads during the critical period of August-October exceeded the target loads set by the TMDL during 2006 and 2007. The data show that Deer Creek Reservoir met the endpoints for no fish kills and in-lake phosphorus concentration, but did not meet the endpoints for DO concentrations in the water column, trophic state index, and algae biomass.

How did local stakeholders benefit from the TMDL process?

Through the TMDL process, stakeholders had the opportunity to claim credit for water quality improvements in Deer Creek Reservoir and play a role in establishing the future direction of water quality management for the reservoir. Striving to achieve the water quality management goals established in the TMDL will benefit stakeholders in a number of ways.

  • Allowing future growth without sacrificing water quality. By incorporating pollutant load reductions and a margin of safety, the TMDL takes into consideration the growth of Wasatch County without compromising the quality of the drinking water and irrigation supply.
  • Ensuring a high quality drinking water supply while keeping down treatment costs. Deer Creek Reservoir is a major source of drinking water for over one million people, distributed by five separate utilities located in Salt Lake, Utah, Wasatch, and Summit counties. Although Deer Creek Reservoir supported its drinking water designated use at the time of TMDL development, the TMDL process revealed the sensitive nature of the reservoir and helped stakeholders set goals to prevent future drinking water designated use impairment.
  • Improved recreational opportunities and aesthetics. Maintaining and reducing phosphorus loads will help to keep Deer Creek Reservoir free from nuisance algae blooms that can affect recreational enthusiasts desire to enjoy activities such as swimming, boating, and fishing on the reservoir.
  • Established sustainable, effective partnerships. The cooperation among partners at all levels, including UDEQ, JTAC, local communities, conservation districts, water suppliers, and watershed groups, have established a strong foundation for maintaining the water quality of Deer Creek Reservoir and addressing future issues.

Table 1. Summary of Deer Creek Reservoir Endpoint Assessment for 2006 and 2007

Parameter (Proposed Target)Meet Endpoint in 2006?Meet Endpoint in 2007?
Percent of the water column with dissolved oxygen concentrations below the target threshold value to support beneficial use (<50% of column with DO<4.0 mg/l)NoNo
Fish habitat (No fish kills)YesYes
In-lake phosphorus concentration (0.025 mg/l TP (Avg all depths))YesYes
In-stream phosphorus concentration (0.030 mg/l TP and 0.020 mg/l DTP)[Information on this endpoint not provided in the 2008 report]
Total Phosphorus loads to lake: Annual (15,300 kg/yr TP and 9,700 kg/yr DTP)YesYes
Total Phosphorus loads to lake: August–October (560 kg/mo TP and 350 kg/mo DTP)NoNo
Average Trophic State Index (40–45)NoNo
Algae biomass (5.1 ug/l Chlorophyll a; 6.5 x 107 um3/ml Biomass; 3.3 x 107 um3/ml Cyanophyta)NoNo

For more information on the Deer Creek Reservoir phosphorus TMDL, contact: Dave Wham (dwham@utah.gov), Utah Department of Environmental Quality; telephone: (801) 538-6052

For more information on the Utah TMDL Program, visit the Utah Division of Water Quality Watershed Management and Planning

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