Johnson Lake
Gosper County, NebraskaView mapDirections
Nutrients and algae run above the regional average.
↓ down from C at the last regrade
- Eutrophic
- Impaired · Algal growth
- #1 of 1 in the county
- 30 ft max depth
- Public access
Johnson Lake in Gosper County, Nebraska has a water quality grade of D (Nutrient-rich). Water clarity: 2.8 ft visibility. Phosphorus: 62.3 µg/L. Chlorophyll-a (algae): 11.3 µg/L.
- Clarity
- 2.8 ft
- Max depth
- ~30 ft est.
- Type
- Eutrophic
- Phosphorus
- 62.3 µg/L
- Chlorophyll-a
- 11.3 µg/L
- Trend
- ↑ Improving
- Public access
- Yes
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Stays near Johnson Lake
Compare lakeside cabins, hotels, and vacation rentals near Johnson Lake in Gosper County, Nebraska — 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 Johnson Lake are listed below.
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Johnson Lake is a productive, nutrient-rich eutrophic lake in Gosper County, Nebraska with an estimated average depth of about 30 feet. Water quality is graded D based on 2 sampling years through 2024. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, NDEE, last sampled 2024-09-26. Grade methodology: LakeQuality methodology.
What Johnson Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Camping1 public campground nearby
Swimming Safety
Grade onlyElevated nutrients
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 D is nutrients and algae, not a swimming clearance. Johnson Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, mercury, nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Water Quality Grade: D (Nutrient-rich)
Very murky, less than 2.8 ft of visibility. Phosphorus 62.3 µg/L. Chlorophyll-a 11.3 µg/L. TSI 60. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.8 ft | Not graded |
| Phosphorus | 62.3 µg/L | Poor |
| Chlorophyll-a (Algae) | 11.3 µg/L | Fair |
| Trophic State Index (TSI) | 60 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~30 ft est. |
| Average Depth | ~29 ft est. |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Nebraska has not published bathymetry for Johnson Lake.
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
- Johnson Lake State Recreation Area InletPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Public campgrounds near Johnson Lake
- Johnson Lake State Recreation Area2.2 km
Nearest public campgrounds in the USGS National Map inventory, within about 3 miles. An empty list means USGS records no campground that close, which is not the same as camping being unavailable. Where the source gives an official reservation link, it is used; the cabin and hotel search does not cover campsites. More camping lakes
Fishing Johnson Lake
Water Quality Trend: ↑ Improving
Based on 13 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.495 m/yr | 13 |
| Phosphorus | → Stable | +0.35 µg/L/yr | 5 |
| Chlorophyll-a | ↑ Improving | -0.61 µg/L/yr | 12 |
Reservoir Info (USACE NID)
Johnson Lake is a man-made reservoir impounded by the Johnson Lake Dam (completed 1941), built primarily for hydroelectric; earth-type dam, 47 ft tall and 4,985 ft long.
- Normal storage
- 54,000 ac-ft
- Max storage
- 59,000 ac-ft
- Hazard class
- High
- Owner
- Central Nebraska Public Power & Irrigation District
All listed purposes: Hydroelectric;Irrigation.
Source: USACE National Inventory of Dams, NID ID NE01025 · Operator website
EPA Impairment Status
Johnson Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit NE-MP2-L0520 · Official waterbody report
County Ranking
Ranked #1 of 1 lakes in Gosper County
Nearby Lakes With Higher Grades
Johnson Lake holds Grade D. 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 Gosper County
Frequently asked questions about Johnson Lake
Where is Johnson Lake?
- Johnson Lake is a lake in Gosper County, Nebraska. LakeQuality grades it D for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Johnson Lake?
- Johnson Lake in Gosper County, Nebraska has a water quality grade of D (Nutrient-rich). Water clarity: 2.8 ft visibility. Phosphorus: 62.3 µg/L. Chlorophyll-a (algae): 11.3 µg/L.
Is Johnson Lake safe to swim in?
- The D is nutrients and algae, not a swimming clearance. Johnson Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, mercury, nutrients (phosphorus, nitrogen). Check local advisories before you swim.
How deep is Johnson Lake?
- No published bathymetric survey covers Johnson Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 30 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Are there boat ramps on Johnson Lake?
- Johnson Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Johnson Lake State Recreation Area Inlet. Public access is listed as yes.
Are there campgrounds on Johnson Lake?
- Johnson Lake has 1 public campground from USGS The National Map within 5 km, including Johnson Lake State Recreation Area. This is a location join, not a booking. Cabins and hotels are listed separately; campsite reservations use the official link when the source provides one.
Explore Johnson Lake across LakeQuality
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Other Grade D Lakes in Nebraska
Eutrophic Lakes in Nebraska
Where this data comes from
161 measurements from 2 monitoring stations, 2012–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Nebraska Department of Environment and Energy
21NEB001_WQX161 samples · 2012–2024
Analytical methods
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
- 447.0 ~ EPA; Chlorophyll a and b in phytoplankton by HPLC/UV
- Total Phosphorus After Block Digestion
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
Public campgrounds from USGS The National Map Structures, within about 3 miles