Knott Creek Reservoir
Humboldt County, Nevada10 acresView mapDirections
Nutrients and algae run well above the regional average.
↓ down from D at the last regrade
- Hypereutrophic
- Impaired · Metals (other than mercury)
- #4 of 4 in the county
- 24 ft max depth
Knott Creek Reservoir in Humboldt County, Nevada has a water quality grade of F (Algae-prone). Phosphorus: 145 µg/L. Chlorophyll-a (algae): 59 µg/L. Surface area: 10 acres.
- Max depth
- ~24 ft est.
- Area
- 10 acres
- Type
- Hypereutrophic
- Phosphorus
- 145 µg/L
- Chlorophyll-a
- 59 µg/L
- Trend
- → Stable
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Stays near Knott Creek Reservoir
Compare lakeside cabins, hotels, and vacation rentals near Knott Creek Reservoir in Humboldt County, Nevada — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water. The water-quality grade measures nutrients and algae, not lodging — cabins and rentals around Knott Creek Reservoir are listed below.
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Watch Knott Creek Reservoir’s letter
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Knott Creek Reservoir is a 10-acre highly nutrient-loaded hypereutrophic lake in Humboldt County, Nevada with an estimated average depth of about 24 feet. Water quality is graded F based on 2 sampling years through 2021. Phosphorus level is declining over recent sampling years. Compared to the 3 other monitored lakes in Humboldt County, Knott Creek Reservoir ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, NDEP, last sampled 2021-10-05. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyAlgae risk
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
The F is nutrients and algae, not a swimming clearance. Knott Creek Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for metals (other than mercury), nutrients (phosphorus, nitrogen), oxygen depletion (low DO), pH / acidity. Check local advisories before you swim.
Water Quality Grade: F (Algae-prone)
No clarity data. Phosphorus 145 µg/L. Chlorophyll-a 59 µg/L. TSI 73. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 145 µg/L | Poor |
| Chlorophyll-a (Algae) | 59 µg/L | Poor |
| Trophic State Index (TSI) | 73 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~24 ft est. |
| Surface Area | 10 acres |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Nevada has not published bathymetry for Knott Creek Reservoir.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Fishing Knott Creek Reservoir
Water Quality Trend: → Stable
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Phosphorus | ↓ Declining | +17.57 µg/L/yr | 6 |
| Chlorophyll-a | ↑ Improving | -18.19 µg/L/yr | 3 |
Reservoir Info (USACE NID)
Knott Creek Reservoir is a man-made reservoir impounded by the Knott Creek Reservoir Dam, built primarily for irrigation on the Knott Creek; masonry-type dam, 28 ft tall and 100 ft long.
- Surface area
- 10 ac
- Normal storage
- 2,000 ac-ft
- Max storage
- 3,860 ac-ft
- Drainage area
- 6.2 sq mi
- Hazard class
- Significant
- Owner
- RDD INC
All listed purposes: Irrigation;Fire Protection, Stock, Or Small Fish Pond;Recreation.
Source: USACE National Inventory of Dams, NID ID NV00004 · Operator website
EPA Impairment Status
Knott Creek Reservoir is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit NV01-NW-05-B_00 · Official waterbody report
County Ranking
Ranked #4 of 4 lakes in Humboldt County
Nearby Lakes With Higher Grades
Knott Creek Reservoir holds Grade F. One nearby lake has a higher nutrient-and-algae grade — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Humboldt County
Frequently asked questions about Knott Creek Reservoir
Where is Knott Creek Reservoir?
- Knott Creek Reservoir is a lake in Humboldt County, Nevada. LakeQuality grades it F for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Knott Creek Reservoir?
- Knott Creek Reservoir in Humboldt County, Nevada has a water quality grade of F (Algae-prone). Phosphorus: 145 µg/L. Chlorophyll-a (algae): 59 µg/L. Surface area: 10 acres.
Is Knott Creek Reservoir safe to swim in?
- The F is nutrients and algae, not a swimming clearance. Knott Creek Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for metals (other than mercury), nutrients (phosphorus, nitrogen), oxygen depletion (low DO), pH / acidity. Check local advisories before you swim.
How deep is Knott Creek Reservoir?
- No published bathymetric survey covers Knott Creek Reservoir, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 24 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 10 acres.
Explore Knott Creek Reservoir across LakeQuality
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Where this data comes from
20 measurements from 1 monitoring station, 2016–2021. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Nevada Division of Environmental Protection
21NEV1_WQX20 samples · 2016–2021
Analytical methods
- 4500 P E ~ Phosphorus in Water by Colorimetry- Ascorbic Acid Method
- 4500 P E ~ Phosphorus by Ascorbic Acid
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- 2130 B ~ Nephelometric Method
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)