Panguitch Lake supports an extremely popular and economically important sport fishery. However, Panguitch Lake also suffers from water quality issues that threaten the fishery due to the risk of major fish loss from lethal temperature and dissolved oxygen levels during the summer months and already limits recreational opportunities due to regular harmful algal blooms in the late summer and early fall. The primary cause of the water quality issues is a high level of nutrients, specifically phosphorous (a TMDL found the Class 3A: Cold water fishery beneficial use was impaired by high total phosphorous and the low dissolved oxygen that results from excess nutrients supporting high phytoplankton production that then uses up oxygen). Nutrient-loading in Panguitch Lake has occurred for many years from a variety of nonpoint sources. Even if these nutrient sources are addressed, the high nutrient levels in Panguitch Lake will likely persist for many years. The fishery, recreational opportunities, and economic potential of Panguitch Lake would benefit greatly from a project that can help to address the existing nutrient load problem.

Significantly reduce the likelihood of a major fish loss at Panguitch Lake from lethal temperature and dissolved oxygen levels during the summer months. Significantly increase recreational opportunities at Panguitch Lake by reducing the frequency and severity of harmful algal blooms in the late summer and early fall.

Panguitch Lake supports an extremely popular and economically important sport fishery. A major fish loss would be a devastating loss for anglers and those who love Panguitch Lake for its social value, as well as those who rely upon the fishery for it's large economic value. The water quality issues that threaten the fishery need to be addressed as soon as possible. Adding a hypolimnetic siphon is one of the most meaningful actions that could be taken to address the water quality issues. Adding a hypolimnetic siphon now dovetails with other, current work going on at Panguitch Lake. A new dam is being constructed at Panguitch Lake and should be completed in 2026. Additionally, we are also working to address the ongoing issue of new nutrient inputs: (1) A fence project to help manage grazing in the Panguitch Lake basin is set to be completed in spring 2026. (2) Translocation of beaver to Bunker Creek and future tributary stream projects (e.g., large woody debris addition) are planned over the next few years to help capture nutrients higher up in the watershed. (3) The Utah Department of Environmental Quality is planning a more formal study and watershed-type plan in the next year or two.

The project would likely help to reduce the stockpile of high nutrient load that exists in Panguitch Lake, improve dissolved oxygen levels for the Class 3A: Cold water fishery benefit (currently impaired by high total phosphorous and low dissolved oxygen), and reduce harmful algal blooms, all issues highlighted in the existing Panguitch Lake TMDL and WQ Management Plan. Measurable objectives would overlap with those described in the Panguitch Lake TMDL and WQ Management Plan, including a mean in-lake concentrations of total phosphorus at 0.025 mg/l and dissolved oxygen above 4.0 mg/l in greater than 50% of the water column, as well as a shift from blue-green dominated algal populations and a Carlson Trophic Status Index less than 50 (Mesotrophy). While the hypolimnetic siphon proposed by this project is not specifically mentioned in the Panguitch Lake TMDL and WQ Management Plan, it would address the exact same issues as the best management practices that are included in the Panguitch Lake TMDL and WQ Management Plan (e.g., elevated total phosphorous load, harmful algal blooms). The project would also help to achieve goals and objectives of the Utah Division of Wildlife Resources' Strategic Plan. Specifically, the project would help to achieve the "Constituency" and "Resource" goals in the Strategic Plan by helping to meet Objectives C1, R2, R2, and R4 (https://wildlife.utah.gov/strategic-plan.html). The project would help to acheive goals and objective of the Panguitch Lake Sport Fishery Management Plan, most notably "...create a quality, sustainable fishery" by ensuring suitable habitat for fish is maintained and protected.

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The project would have a direct and major positive impact on water quality. The anticipated water quality improvement from this project would include lower nutrient loads, better dissolved oxygen levels, and fewer fish kills and harmful algal blooms. Specifically, there would likely be a reduced total phosphorous load; however, the expected load reduction in total phosphorous is difficult to quantify because the design for the hypolimnetic drain has not been completed and modeling tools do not appear to include this type of project.

Compliance will be completed by start of FY27. Most of the compliance work (e.g., cultural, section 7) for the project footprint was completed as part of the new dam construction and does not need to be repeated. The Utah Division of Water Rights was consulted and a Stream Alteration Permit is not required. We are coordinating with the U.S. Army Corps of Engineers and are on schedule to obtain a Nationwide Permit by FY27.

A siphon consisting of roughly 2,600 feet of 24-inch outer diameter, 4710 HDPE, pipeline would be installed to pull water for irrigation releases from the most problematic, nutrient-rich and anoxic portions of Panguitch Lake. Hydraulic calculations have been completed to verify that the siphon project is feasible and can discharge enough water from Panguitch Lake's hypolimnion to significantly improve the lake's water quality over the typical range of reservoir pool elevations that occur. The Utah Division of Wildlife Resources is working closely with Utah Division of Water Resources engineer's on design. Please see "Panguitch Lake Hypolimnetic Siphon Plan of Development" in "Images/Documents" for details. Most materials would be purchased in FY27 (late spring or early summer of 2027) and the project would be implemented (i.e., construction) in FY28 (fall of 2027).

The Utah Division of Water Quality currently monitors, and plans to continue monitoring, the water quality parameters that would be of interest for determining project effectiveness. Specifically, harmful algal blooms, temperature, pH, dissolved oxygen, Secchi depth, and total phosphorus, with many of the parameters planned to be monitored every 6 weeks. If the project were to have a significant impact on these parameters, it would be captured. The Utah Division of Wildlife Resources is available to help the Utah Division of Water Quality with sample collection. Additionally, the Utah Division of Wildlife Resources regularly monitors the fish population at Panguitch Lake, documenting fish abundance, size, condition, and, when they occur, fish kills.

The primary partnership for this project includes: Utah Department of Natural Resources (Division of Wildlife and Water Resources), Utah Department of Environmental Quality, U.S. Forest Service, and the local irrigation company.

In general, the siphon is designed such that its operation is primarily passive, and pumping will only be required during priming, so there should be minimal maintenance required. As mentioned earlier, there is additional work being completed and planned to address the issue of new nutrient inputs (e.g., grazing management, nutrient capture further up in the drainage, identifying other sources and creating a watershed plan).

The project is critical for the sustainable use of recreation at Panguitch Lake.