E A Patterson Lake
Stark County, North Dakota2,158 acresView mapDirections
Nutrients and algae sit mid-range for this region.
↑ up from D at the last regrade
- Eutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- #1 of 3 in the county
- Public access
- Limited data
E A Patterson Lake in Stark County, North Dakota has a water quality grade of C (Fair). Water clarity: 6 ft visibility. Phosphorus: 246 µg/L. Chlorophyll-a (algae): 15.9 µg/L. Surface area: 2158 acres.
- Clarity
- 6 ft
- Typical in August
- 70°F
- Area
- 2,158 acres
- Type
- Eutrophic
- Trend
- → Stable
- Public access
- Yes
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Watch E A Patterson Lake’s letter
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E A Patterson Lake is a 2,158-acre productive, nutrient-rich eutrophic lake in Stark County, North Dakota. Water quality is graded C based on 1 sampling years through 2023. Phosphorus level is declining over recent sampling years. Limited fish-species data available. Public access is available. Compared to the 2 other monitored lakes in Stark County, E A Patterson Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, NDDEQ, last sampled 2023-05-23. Grade methodology: LakeQuality methodology.
What E A Patterson Lake is good for
From access and monitoring records, not editorial picks.
- Big water2,158 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 C is nutrients and algae, not a swimming clearance. E A Patterson Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen), sediment / turbidity, turbidity. Check local advisories before you swim.
Water Quality Grade: C (Fair)
Murky, only visible to about 6 ft. Phosphorus 246 µg/L. Chlorophyll-a 15.9 µg/L. TSI 64. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 6 ft | Not graded |
| Phosphorus | 246 µg/L | Not graded |
| Chlorophyll-a (Algae) | 15.9 µg/L | Fair |
| Trophic State Index (TSI) | 64 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Water Temperature
E A Patterson Lake typically sits around 70°F at the surface in August. Summer average is about 68°F. Usually warmest in Jul (about 71°F) and coldest in Feb (about 36°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 355 field readings (2010–2023) via the EPA Water Quality Portal. See the full E A Patterson Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 2,158 acres |
| Public Access | Yes |
No bathymetric survey has been published for E A Patterson Lake, so its depth is not documented here.
Fishing E A Patterson Lake
Water Quality Trend: → Stable
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Phosphorus | ↓ Declining | +13.67 µg/L/yr | 2 |
| Chlorophyll-a | ↑ Improving | -1.24 µg/L/yr | 4 |
Reservoir Info (USACE NID)
E A Patterson Lake is a man-made reservoir impounded by the Dickinson Dam (completed 1950), built primarily for irrigation on the HEART RIVER; earth-type dam, 65 ft tall and 2,275 ft long.
- Surface area
- 2,158 ac
- Normal storage
- 8,612 ac-ft
- Max storage
- 26,462 ac-ft
- Drainage area
- 401.42 sq mi
- Hazard class
- High
- Owner
- BUREAU OF RECLAMATION
All listed purposes: Irrigation;Water Supply.
Source: USACE National Inventory of Dams, NID ID ND00148 · Operator website · Matched by proximity (0.29 km)
EPA Impairment Status
E A Patterson Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit ND-10130202-002-L_00 · Official waterbody report · Matched by proximity (2.7 km)
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of E A Patterson Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 1 facility has a reported Clean Water Act violation in the past three years.
- Dickinson City OfDickinson · 2.2 mi away · NPDES ND0023175MajorRecent violation
- Southwest Water AuthorityDickinson · 1.3 mi away · NPDES ND0023183
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
County Ranking
Ranked #1 of 3 lakes in Stark County
Nearby Lakes in Stark County
Frequently asked questions about E A Patterson Lake
Where is E A Patterson Lake?
- E A Patterson Lake is a lake in Stark County, North Dakota. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for E A Patterson Lake?
- E A Patterson Lake in Stark County, North Dakota has a water quality grade of C (Fair). Water clarity: 6 ft visibility. Phosphorus: 246 µg/L. Chlorophyll-a (algae): 15.9 µg/L. Surface area: 2158 acres.
Is E A Patterson Lake safe to swim in?
- The C is nutrients and algae, not a swimming clearance. E A Patterson Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen), sediment / turbidity, turbidity. Check local advisories before you swim.
What is the water temperature of E A Patterson Lake?
- E A Patterson Lake typically sits around 70°F at the surface in August, from 355 EPA Water Quality Portal field readings (2010–2023). That is a typical value for the month, not a live reading.
Explore E A Patterson Lake across LakeQuality
Depth, room, public access, and the state wake-sport rules
Species activity outlook by water temperature and season
Where to stay at North Dakota's top lakes, each with its grade
High nutrients, frequent algae, reduced clarity
North Dakota's cleanest and most-polluted lakes, ranked
Planning a trip around Theodore Roosevelt?
E A Patterson Lake is about 35 miles from Theodore Roosevelt National Park. Crowds there swing hard by season, so the month you pick changes both how busy the park is and what lodging costs.
Best time to visit Theodore Roosevelt →More North Dakota Lake Rankings
Other Grade C Lakes in North Dakota
Eutrophic Lakes in North Dakota
Where this data comes from
18 measurements from 1 monitoring station, 2020–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- USGS North Dakota Water Science Center
USGS-ND18 samples · 2020–2023
Analytical methods
- P, wu, WCA, persulfate CF color
- Plant pigments, sonication & 445
- YSI EXO turbidity sensor, FNU
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Depth, fish, and access data from North Dakota Game & Fish