North Sterling Reservoir
Logan County, Colorado2,880 acresView mapDirections
Nutrients and algae run well above the regional average.
- Hypereutrophic
- #2 of 2 in the county
- 89 ft max depth
- Public access
- Limited data
North Sterling Reservoir in Logan County, Colorado has a water quality grade of F (Algae-prone). Water clarity: 1.1 ft visibility. Phosphorus: 145 µg/L. Chlorophyll-a (algae): 198.1 µg/L. Surface area: 2880 acres.
- Clarity
- 1.1 ft
- Max depth
- ~89 ft est.
- Area
- 2,880 acres
- Type
- Hypereutrophic
- Public access
- Yes
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North Sterling Reservoir is a 2,880-acre highly nutrient-loaded hypereutrophic lake in Logan County, Colorado with an estimated average depth of about 89 feet. Water quality is graded F based on 3 sampling years through 2021. Limited fish-species data available. Public access is available with 2 public boat landings. Compared to the 1 other monitored lakes in Logan County, North Sterling Reservoir ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, CDPHE, last sampled 2021-09-21. Grade methodology: LakeQuality methodology.
What North Sterling Reservoir is good for
From access and monitoring records, not editorial picks.
- Boat launch2 documented ramps
- Big water2,880 acres
Swimming Safety
Grade onlyLimited data
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. North Sterling Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for metals (other than mercury), oxygen depletion (low DO). Check local advisories before you swim.
Water Quality Grade: F (Algae-prone)
Very murky, less than 1.1 ft of visibility. Phosphorus 145 µg/L. Chlorophyll-a 198.1 µg/L. TSI 78. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.1 ft | Not graded |
| Phosphorus | 145 µg/L | Poor |
| Chlorophyll-a (Algae) | 198.1 µg/L | Poor |
| Trophic State Index (TSI) | 78 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~89 ft est. |
| Average Depth | ~47 ft est. |
| Surface Area | 2,880 acres |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Colorado has not published bathymetry for North Sterling 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.
Recreation & Access
- North Sterling State ParkPublic
- North Sterling State ParkPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing North Sterling Reservoir
Reservoir Info (USACE NID)
North Sterling Reservoir is a man-made reservoir impounded by the Point of Rocks (completed 1948), built primarily for irrigation on the Cedar Creek; earth-type dam, 86 ft tall and 5,080 ft long.
- Surface area
- 2,880 ac
- Normal storage
- 74,590 ac-ft
- Max storage
- 113,600 ac-ft
- Drainage area
- 370 sq mi
- Hazard class
- High
- Owner
- NORTH STERLING IRRIGATION DISTRICT (YAHN, JIM)
Source: USACE National Inventory of Dams, NID ID CO00384 · Operator website
EPA Impairment Status
North Sterling Reservoir is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit COSPLS03_B · Official waterbody report
County Ranking
Ranked #2 of 2 lakes in Logan County
Nearby Lakes in Logan County
Frequently asked questions about North Sterling Reservoir
Where is North Sterling Reservoir?
- North Sterling Reservoir is a lake in Logan County, Colorado. LakeQuality grades it F for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for North Sterling Reservoir?
- North Sterling Reservoir in Logan County, Colorado has a water quality grade of F (Algae-prone). Water clarity: 1.1 ft visibility. Phosphorus: 145 µg/L. Chlorophyll-a (algae): 198.1 µg/L. Surface area: 2880 acres.
Is North Sterling Reservoir safe to swim in?
- The F is nutrients and algae, not a swimming clearance. North Sterling Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for metals (other than mercury), oxygen depletion (low DO). Check local advisories before you swim.
How deep is North Sterling Reservoir?
- No published bathymetric survey covers North Sterling Reservoir, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 89 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 2880 acres.
Are there boat ramps on North Sterling Reservoir?
- North Sterling Reservoir has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include North Sterling State Park, North Sterling State Park. Public access is listed as yes.
Explore North Sterling Reservoir across LakeQuality
Species activity outlook by water temperature and season
Where to stay at Colorado's top lakes, each with its grade
Very high nutrients, dense algae, poor clarity
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Where this data comes from
18 measurements from 2 monitoring stations, 2021. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Colorado Dept. of Public Health & Environment-WQCD
21COL001_WQX18 samples · 2021
Analytical methods
- Secchi disk depth measurement
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- Nitrogen in Water by Pyrolysis Detection
Monitoring station identifiers (2)
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)
Named boat-access points from the USGS National Boat Ramps inventory