Upper Orono Lake
Upper Orono Lake in Sherburne County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 3.5 ft visibility. Phosphorus: 130.5 µg/L. Chlorophyll-a (algae): 47.5 µg/L.
- Clarity
- 3.5 ft
- Typical in August
- 68°F
- Mean depth
- ~7 ft est.
- Type
- Eutrophic
- Trend
- ↑ Improving
- Public access
- Yes
- Ice-out
- Apr 3
- Open water
- 240 days
Grade F measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Upper Orono Lake →
Next lake in Sherburne County
Upper Orono Lake is a productive, nutrient-rich eutrophic lake in Sherburne County, Minnesota with an estimated average depth of about 7 feet. Water quality is graded F based on 2 sampling years through 2025. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 17 other monitored lakes in Sherburne County, Upper Orono Lake ranks #14 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-29. Grade methodology: LakeGrade methodology.
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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.
Algae and nutrients are often high — check current advisories before swimming. Skip the water if you see scum or a paint-like bloom
Water Quality Grade: F (Algae-prone)
Murky, only visible to about 3.5 ft. Phosphorus level: 130.5 µg/L. Chlorophyll-a: 47.5 µg/L. Trophic State Index: 67.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.5 ft | Not graded |
| Phosphorus | 130.5 µg/L | Poor |
| Chlorophyll-a (Algae) | 47.5 µg/L | Poor |
| Trophic State Index (TSI) | 67 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Upper Orono Lake
Compare lakeside cabins, hotels, and vacation rentals near Upper Orono Lake in Sherburne County, Minnesota — 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 Upper Orono Lake are listed below.
Top-rated places to stay near Upper Orono Lake
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
Upper Orono Lake typically sits around 68°F at the surface in August. Summer average is about 72°F. Usually warmest in Jul (about 77°F) and coldest in May (about 63°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 30 field readings (2024–2025) via the EPA Water Quality Portal. See the full Upper Orono Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Upper Orono Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was high (483,059 cells/mL) on October 4, 2025.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Lake Details
| Characteristic | Value |
|---|---|
| Average Depth | ~7 ft est. |
| Public Access | Yes |
Depth marked “est.” is a modeled estimate from HydroLAKES, not a measured survey. Minnesota has not published bathymetry for Upper Orono 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
- Orono LakePublic
Fishing Upper Orono Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Upper Orono Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Public Water Access Sites — Upper OronoPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.089 m/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (10 observations).
Estimated open water season: 240 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2017-03-27 (2017) | 2018-04-27 (2018) |
| Ice-In | 2018-11-10 (2018) | 2015-12-19 (2015) |
Most recent ice-out: 2025-03-28
EPA Impairment Status
Upper Orono Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN71-0013-01 · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Upper Orono Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Otsego Wwtp WestOtsego · 4.3 mi away · NPDES MN0066257Recent violation
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 #14 of 18 lakes in Sherburne County
Nearby Lakes With Higher Grades
Upper Orono Lake holds Grade F. 3 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
Nearby Lakes in Sherburne County
Frequently asked questions about Upper Orono Lake
What is the water quality grade for Upper Orono Lake?
- Upper Orono Lake in Sherburne County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 3.5 ft visibility. Phosphorus: 130.5 µg/L. Chlorophyll-a (algae): 47.5 µg/L.
Is Upper Orono Lake safe to swim in?
- Algae and nutrients are often high — check current advisories before swimming. Skip the water if you see scum or a paint-like bloom. Upper Orono Lake has a water quality grade of F (Algae-prone). Algae concentration (chlorophyll-a) is 47.5 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Upper Orono Lake?
- Upper Orono Lake typically sits around 68°F at the surface in August, from 30 EPA Water Quality Portal field readings (2024–2025). That is a typical value for the month, not a live reading.
How deep is Upper Orono Lake?
- No published bathymetric survey covers Upper Orono Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 7 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
When does Upper Orono Lake thaw?
- Upper Orono Lake typically has ice-out around Apr 3. Ice typically forms around Nov 29. The open water season is approximately 240 days.
Does Upper Orono Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Upper Orono Lake (clouds, ice, or an off-season gap). The most recent reading was high (483,059 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.
Are there boat ramps on Upper Orono Lake?
- Upper Orono Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Orono Lake. Public access is listed as yes.
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Where this data comes from
100 measurements from 3 monitoring stations, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA100 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (3)
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)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory
Ice data from Minnesota DNR Climate