TMDL For Temperature in Ken’s Lake, Utah Prepared by Utah ✓ Solved

```html

The document is identified as a TMDL for Ken’s Lake and is officially submitted to the U.S. EPA to act upon and approve as a TMDL.

Ken’s Lake is an off-stream reservoir at the foot of the west slopes of the La Sal Mountains in southeastern Utah. The impoundment is approximately 10 miles south of Moab and is part of the Mill Creek Watershed. The valley is a long graben, where the underlying rocks have dropped below the surrounding terrain. It is an arid redrock desert. Water is brought into the lake via the Sheley Diversion Tunnel from Mill Creek. The Grand County Water Conservancy District initiated development of Ken’s Lake in 1979 to serve the agricultural irrigation needs of residents of Moab’s Spanish Valley. The reservoir includes a dam that is 95 feet high and 4,050 feet long. The reservoir has a surface area of 35 hectares/86 acres, is 2,690 feet long, 1,400 feet wide, and has a maximum depth of 70 feet.

The Utah Division of Water Quality (DWQ) has assessed and classified the beneficial uses of Ken’s Lake using Utah’s water quality standards. The water quality numeric standard for temperature in Class 3A fisheries is 20 degrees Celsius. Ken’s Lake was found to exceed this standard periodically from June through September. The state will develop a site-specific standard for temperature in Ken’s Lake or reclassify the lake as a warm water fishery (3B), based on data from this TMDL study.

Ken’s Lake is supplied with water through a diversion tunnel, and thermal impairment is primarily caused by solar heating. The only other significant sources of cooling or heating are evaporative cooling from wind, sensible heat loss, and inflows from the diversion stream. The temperature in Ken’s Lake will continue to exceed the state’s standard during the summer months due to naturally occurring thermal conditions. To comply with TMDL requirements, strategies are suggested, including increasing vegetation shading and managing reservoir depths.

Paper For Above Instructions

Ken’s Lake, located in San Juan County, Utah, is a vital water body that offers recreational opportunities and agricultural benefits to the local community. Ken’s Lake is situated approximately 10 miles south of Moab and is encompassed in the Mill Creek Watershed, characterized by an arid red rock desert landscape with sparse vegetation comprised mainly of shrubs and grasses. This lake serves as an irrigation reservoir for the agricultural needs of Spanish Valley and supports a variety of aquatic life, including various species of fish, making it a significant habitat for cold water species. The Utah Division of Wildlife Resources (UDWR) manages the lake as a cold water fishery, stocking approximately 11,000 catchable-size rainbow trout annually.

In assessing the quality of Ken’s Lake, the Utah Division of Water Quality (DWQ) identified several beneficial use classifications to protect the ecosystem and the aquatic life within the lake. The primary classifications associated with Ken’s Lake include: Class 2B, protected for recreational use and aesthetics; Class 3A, designated for cold water species of game fish; and Class 4, which covers agricultural uses such as irrigation. Unfortunately, the Class 3A classification has been identified as impaired due to temperature concerns. Specifically, the lake's temperature periodically exceeds the water quality numeric standard of 20 degrees Celsius, particularly during the critical summer months from June through September.

The primary cause of temperature impairment in Ken’s Lake stems from natural solar heating and evaporation, exacerbated by the lack of shading vegetation, sensible heat loss, and the thermal conditions of inflows. Solar radiation significantly influences the thermal environment of the lake by raising water temperatures beyond the state’s acceptable thresholds for cold water species. More precisely, the inflow water from the Sheley Diversion Tunnel, which carries water from Mill Creek, is measured to range from 15 to 19 degrees Celsius, indicating that even the source water contributes to the warming of the lake. This heating effect is compounded during the summer months, with temperatures reaching levels that hinder the sustainability of colder water species like trout, especially during peak summer months.

The current total load for temperature in Ken’s Lake reflects this ongoing challenge, as water temperatures throughout the summer consistently exceed the 20 degrees Celsius standard, making maintenance of a viable trout fishery unfeasible. The required water quality endpoint mandates that the average temperature must not surpass this threshold, yet maintaining such conditions during the summer months when natural thermal inputs peak proves difficult. The implications of these high temperatures not only threaten fish survival but also disrupt the ecological balance necessary for the overall health of the aquatic ecosystem.

In response to these impairments, the TMDL plan outlines strategies to address the temperature issues effectively. The primary action proposed by the DWQ involves developing a site-specific standard for temperature or considering a reclassification of the lake as a warm water fishery (3B). Such measures aim to ensure that the water body's use aligns better with its natural thermal attributes, thereby facilitating the management of aquatic species that can withstand higher temperatures. Furthermore, the implementation of riparian improvements and increasing shading vegetation along the inflow channel are practical methods identified in the TMDL to enhance the cooling effects needed to mitigate temperature spikes and improve overall water quality.

In conclusion, Ken’s Lake presents a compelling case study regarding the importance of effective water management and TMDL implementations in addressing water quality impairments. Through a comprehensive understanding of the beneficial uses, impairment factors, and ongoing strategies to mitigate temperature-related concerns, stakeholders can work towards achieving compliance with state standards. Collaboration among local entities, regulatory agencies, and the community will be vital in protecting and preserving Ken's Lake, thus ensuring its long-term viability as a critical resource for both aquatic life and human activities.

References

  • Utah Division of Water Quality. (2023). Water Quality Standards.

  • Utah Department of Environmental Quality. (2023). Ken's Lake TMDL Report.

  • Grand County Water Conservancy District. (2023). Ken's Lake Management Plan.

  • Utah Division of Wildlife Resources. (2023). Trout Stocking Information.

  • U.S. Environmental Protection Agency. (2023). Total Maximum Daily Load (TMDL) Reports.

  • U.S. Geological Survey. (2023). Hydrology of the Mill Creek Watershed.

  • Moab Local Government. (2023). Community Aquatic Resource Management.

  • National Oceanic and Atmospheric Administration. (2023). Climate Data for Moab, Utah.

  • Smith, J., & Brown, A. (2023). Effects of Temperature on Aquatic Ecosystems: A Review.

  • Jones, R. (2023). Strategies for Sustaining Cold Water Fisheries in a Changing Climate.

```