Impaired Lakes in Utah
55 of 121 graded Utah lakes (45%) are officially listed as impaired under Clean Water Act §303(d) in the most recent EPA ATTAINS reporting cycle. 28 have an approved TMDL restoration plan.
Top Causes of Impairment in Utah
Reading the Utah impairment landscape
Utah reports 55 impaired lakes — 45% of the state's 121 tracked water bodies. That share is high enough to make impairment a meaningful planning concern: roughly one in four lakes carries at least one §303(d) listing for a pollutant exceeding standards. The list below isn't a niche concern — it's a significant chunk of the state's surface-water inventory.
The leading impairment cause in Utah is Oxygen depletion (low DO). Each impairment category carries its own use-restriction implications — some affect fish consumption, some affect swimming, some affect aquatic-life habitat. Click through to the specific lake records below for the pollutant list and the TMDL (Total Maximum Daily Load) status, which determines whether a cleanup plan is in place.
Impaired-waters listings come from the state environmental agency's §303(d) submission to EPA, refreshed on a roughly 2-year cycle. A listed lake stays on the list until either a TMDL is established and the cleanup completes, or subsequent monitoring shows the pollutant concentrations no longer exceed water-quality standards. The list below reflects the most recent available Utah submission to the EPA Assessment, Total Maximum Daily Load Tracking and Implementation System (ATTAINS) dataset.
All 55 EPA-Listed Impaired Lakes in Utah
| Lake | County | Grade | Causes | TMDL |
|---|---|---|---|---|
| Wide Hollow Reservoir | Garfield | A | Oxygen depletion (low DO), pH / acidity, Temperature | — |
| Starvation Reservoir | Duchesne | A | Oxygen depletion (low DO), Temperature | — |
| Recapture Reservoir | San Juan | A | Oxygen depletion (low DO), Temperature | — |
| Red Fleet Reservoir | Uintah | A | Oxygen depletion (low DO), Temperature | ✓ |
| Silver Lake Flat Reservoir | Utah | A | Oxygen depletion (low DO) | — |
| Salem Pond | Utah | A | Pathogens (E. coli, fecal) | — |
| Grantsville Reservoir | Tooele | A | Oxygen depletion (low DO), pH / acidity, Temperature | — |
| Gunlock Reservoir | Washington | A | Nutrients (phosphorus, nitrogen) | ✓ |
| Newton Reservoir | Cache | A | Nutrients (phosphorus, nitrogen), Oxygen depletion (low DO), Temperature | ✓ |
| Hyrum Reservoir | Cache | A | Nutrients (phosphorus, nitrogen) | ✓ |
| Mantua Reservoir N | Box Elder | A | Algal growth, Nutrients (phosphorus, nitrogen), Oxygen depletion (low DO) +1 more | ✓ |
| Big Sand Wash Reservoir | Duchesne | A | Impaired biota (cause unknown), Metals (other than mercury), Oxygen depletion (low DO) +2 more | ✓ |
| Brough Reservoir | Uintah | A | Mercury, Oxygen depletion (low DO), Temperature | ✓ |
| Palisade Lake | Sanpete | A | Temperature | — |
| Tropic Reservoir | Garfield | A | pH / acidity | — |
| Nine Mile Reservoir | Sanpete | A | Nutrients (phosphorus, nitrogen), Oxygen depletion (low DO), pH / acidity +1 more | — |
| Steinaker Reservoir | Uintah | A | Oxygen depletion (low DO), Temperature | ✓ |
| Paradise Park Reservoir | Uintah | B | pH / acidity | — |
| Lyman Lake | Summit | B | Oxygen depletion (low DO) | — |
| Tibble Fork Reservoir | Utah | C | Oxygen depletion (low DO) | — |
| Strawberry Lake | Wasatch | C | Nutrients (phosphorus, nitrogen), pH / acidity | ✓ |
| Calder Reservoir | Uintah | C | Ammonia, Nutrients (phosphorus, nitrogen), Oxygen depletion (low DO) +2 more | ✓ |
| Upper Enterprise Reservoir | Washington | C | Oxygen depletion (low DO), pH / acidity, Temperature | — |
| East Canyon Reservoir | Morgan | C | Algal growth, Nutrients (phosphorus, nitrogen), Pathogens (E. coli, fecal) | ✓ |
| Lower Gooseberry Reservoir | Sanpete | C | Nutrients (phosphorus, nitrogen) | — |
| Newcastle Reservoir | Iron | C | Mercury, Nutrients (phosphorus, nitrogen), Oxygen depletion (low DO) +2 more | ✓ |
| Navajo Lake | Kane | C | pH / acidity | — |
| Strawberry Reservoir Strawberry Bay T | Wasatch | C | Oxygen depletion (low DO), pH / acidity | — |
| Minersville Reservoir | Beaver | C | Nutrients (phosphorus, nitrogen), Oxygen depletion (low DO), pH / acidity +1 more | ✓ |
| Smith And Morehouse Reservoir | Summit | C | Metals (other than mercury) | — |
| Three Creeks Reservoir | Beaver | C | pH / acidity | — |
| Lower Bowns Reservoir | Garfield | D | Nutrients (phosphorus, nitrogen), Oxygen depletion (low DO), pH / acidity +1 more | — |
| Cutler Reservoir | Cache | D | Nutrients (phosphorus, nitrogen) | ✓ |
| Big East Lake | Utah | D | Algal growth, Nutrients (phosphorus, nitrogen), Oxygen depletion (low DO) +2 more | — |
| Johnson Reservoir | Sevier | D | Nutrients (phosphorus, nitrogen) | ✓ |
| Mill Meadow Reservoir | Wayne | D | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Scofield Reservoir | Carbon | D | Algal growth, Nutrients (phosphorus, nitrogen), Oxygen depletion (low DO) +1 more | ✓ |
| Piute Reservoir | Piute | D | Nutrients (phosphorus, nitrogen), Oxygen depletion (low DO), pH / acidity +1 more | — |
| Otter Creek Reservoir | Piute | D | Algal growth, Nutrients (phosphorus, nitrogen), Temperature | ✓ |
| Baker Dam Reservoir | Washington | D | Nutrients (phosphorus, nitrogen), Oxygen depletion (low DO), Temperature | ✓ |
| Browne Lake | Daggett | D | Oxygen depletion (low DO), pH / acidity | ✓ |
| Panguitch L Shore Lake | Garfield | D | Algal growth, Nutrients (phosphorus, nitrogen), pH / acidity | ✓ |
| Matt Warner Reservoir E | Uintah | D | Algal growth, Nutrients (phosphorus, nitrogen), Oxygen depletion (low DO) +2 more | ✓ |
| Birch Creek Reservoir | Rich | D | pH / acidity, Temperature | — |
| Koosharem Reservoir | Sevier | F | Nutrients (phosphorus, nitrogen), Oxygen depletion (low DO), pH / acidity +1 more | ✓ |
| Rockport Mid Lake | Summit | NR | Algal growth, Pathogens (E. coli, fecal) | ✓ |
| Strawberry Marina Lake | Wasatch | NR | Oxygen depletion (low DO), pH / acidity | — |
| Pineview North Arm Lake | Weber | NR | Algal growth, Nutrients (phosphorus, nitrogen), Oxygen depletion (low DO) +3 more | ✓ |
| Echo Mid Res Lake | Summit | NR | Algal growth, Nutrients (phosphorus, nitrogen) | ✓ |
| Lake Canyon Lake | Duchesne | NR | Metals (other than mercury), pH / acidity, Salinity / chlorides +1 more | — |
| Forsyth Reservoir | Sevier | NR | Nutrients (phosphorus, nitrogen) | ✓ |
| Little Creek Reservoir | Rich | NR | pH / acidity, Temperature | — |
| Cutler Reservoir | Cache | NR | Nutrients (phosphorus, nitrogen) | ✓ |
| Manning Creek Lake | Piute | NR | Algal growth, Nutrients (phosphorus, nitrogen), pH / acidity | — |
| Pond | Utah | NR | Ammonia | — |
Frequently Asked Questions
How many lakes are impaired in Utah?
55 of 121 graded Utah lakes (45%) are listed as impaired in the most recent EPA ATTAINS reporting cycle. Of those, 48 are on the federal Clean Water Act §303(d) list and 28 have an approved Total Maximum Daily Load (TMDL) restoration plan.
What does Clean Water Act §303(d) mean?
Section 303(d) of the federal Clean Water Act requires every state to identify waters that don't meet water quality standards even after pollution control measures. Each listed water must then have a Total Maximum Daily Load (TMDL) developed — a plan that caps how much of each pollutant can enter the waterbody. The "303(d) list" is the impaired-waters list. The EPA reviews each state's list every two years.
What are the top causes of impairment in Utah?
The most common causes flagged across Utah's impaired lakes are: Oxygen depletion (low DO) (29 lakes); Nutrients (phosphorus, nitrogen) (28 lakes); pH / acidity (27 lakes); Temperature (26 lakes); Algal growth (12 lakes); Pathogens (E. coli, fecal) (4 lakes). Mercury is widespread in fish tissue across the upper Midwest from atmospheric deposition. Nutrient impairment (phosphorus, nitrogen) typically reflects agricultural runoff and urban stormwater.
Can I swim in an impaired lake?
It depends on the cause of impairment. A lake impaired for "mercury in fish tissue" is generally safe to swim in — the warning is about long-term consumption of fish. A lake impaired for "pathogens" (E. coli) or "algal growth" may pose a swimming risk and often has a separate beach advisory. Check the cause categories listed for each lake below, and consult your state health department's beach monitoring program for current advisories.
Where does this impairment data come from?
Every impairment record on this page comes from the EPA's ATTAINS (Assessment and TMDL Tracking and Implementation System) public dataset, the federal repository of state-reported water quality assessments. EPA ATTAINS is published as GeoParquet files on the EPA Office of Water S3 bucket and refreshed several times per year. Causes and use-support codes follow EPA's standard taxonomy.
More on impaired waters
What it means when a lake is listed as impaired, why mercury is the most common reason, and why a listed lake can still be clear water with a good grade.
Why states issue fish-consumption advisories, which contaminants — mercury, PCBs, PFAS — drive them, and how to eat the fish you catch more safely.
How phosphorus and nutrient runoff drive algae growth and turn lakes green, where the nutrients come from, and what it means for a lake's grade.
Which lakes are actually improving: multi-year EPA monitoring trends, the named recoveries still in progress, and what it takes to move a letter grade.
Data source
Impairment data from the EPA ATTAINS (Assessment and TMDL Tracking and Implementation System) public dataset. Assessment unit IDs are matched to LakeQuality lakes by name and proximity; some lakes may not appear here if their ATTAINS name doesn't match our naming convention. For an official query, consult .