Panguitch Lake Hypolimnetic Siphon

Panguitch Lake is an important cold-water fishery and recreation area for southern Utah communities. This project is designed to improvewater quality in the lake and in Panguitch Creek, the outlet to the lake.

The problem

Panguitch Lake, a vital sport fishery and recreational hub in southern Utah, is threatened by declining water quality, including recurring harmful algal blooms (HABs) and fish kills. Elevated internal phosphorus levels fuel cyanobacteria and phytoplankton growth, which depletes oxygen and promotes further algae blooms, compromising the lake's cold-water fishery and recreational value. A comprehensive 2004 data analysis—The Panguitch Lake Total Maximum Daily Load and Water Quality Management Plan (TMDL)—identified internal nutrient loads as the primary source of pollution, accounting for an estimated 77% of the total phosphorus load.

The solution: hypolimnetic siphon

The proposed solution to this problem is to construct a passive hypolimnetic siphon to extract nutrient-rich water from the lake bottom. Lake sediments act as a nutrient bank. A successful siphon will pull a set amount of nutrients from the bottom layer of the lake, or hypolimnion, each year, and release it to Panguitch Creek, the outlet of the lake. This selective withdrawal removes a targeted 15–30% of the hypolimnetic volume annually, specifically during the period of thermal stratification (mid-June to mid-September). Removing the existing nutrient bank will address the root problem and provide a long-term solution to improve water quality, protect the fishery, and ensure Panguitch Lake is a great place to visit.

Hypolimnetic withdrawal is a well-established in-lake restoration technique with over 60 years of documented application across approximately 50 lakes in Europe and North America. The technique addresses the root cause of eutrophication in stratified lakes—rather than symptoms—by physically exporting the nutrient-enriched bottom water that fuels HABs and oxygen depletion during and after stratification. Importantly, the effectiveness of hypolimnetic withdrawal strengthens over time supporting a long-term management commitment to the siphon system.

An initial modeling effort indicated that adding cold, nutrient-rich lake water resulted in creek temperatures decreasing by approximately 2–4°C. The estimated decrease in temperature would support the coldwater aquatic habitat in Panguitch Creek, especially during the summer months when the temperature of the creek often exceeds the 20°C water quality criterion for a coldwater fishery.

Funding and timeline

This project is a collaborative effort between Utah Department of Natural Resources, Utah Division of Water Quality, West Panguitch Irrigation Company, and the U.S. Forest Service. Funding will be secured through several sources that include federal 319, state nonpoint source, Utah Department of Natural Resources, and in-kind contributions. The timeline for project implementation will be to complete all necessary surveys, planning, and design by late 2027 or early 2028. Construction of the hypolimnetic siphon will begin in spring2027 after full project funding is secured. The target completion date for the project is June 30, 2028. The long-term timeline for realizing benefits that can achieve specific, measurable goals will likely be in the 10-20 year range.

Monitoring and evaluation

A robust monitoring program is already underway to capture pre and post project water quality conditions. We currently monitor water quality in the lake, inflows to the lake, and in Panguitch Creek, the outflow of the lake. HABs, temperature, pH, dissolved oxygen, and total nutrients are monitored and will continue to be monitored on a regular basis. Continuous temperature data is collected at several sites andcontinuous dissolved oxygen is monitored at one location in Panguitch Creek as of spring 2026. Additionally, Utah Division of Wildlife regularly monitors the fish population in the lake, documenting fish abundance, size, condition, and, when they occur, fish kills.

The siphon alone won’t save the lake

Managing nonpoint sources of water pollution entering Panguitch Lake is critical, and we need your help. What is a nonpoint source? Everything on the land that impacts the water—whether it's a septic tank that's gone a year or two without maintenance or cattle and horses grazing along the creeks or lakebed. These seemingly insignificant activities add up to a load of nutrients entering the lake. Help break the cycle by maintaining your septic tank and keeping livestock away from live water. If you need financial or technical assistance, you can find more information on our nonpoint grant portal.

Questions?