Diamond Lake
Douglas County, OregonView mapDirections
Oregon DEQ publishes the water-quality measurements for Diamond Lake. Here is what has been measured.
- Hypereutrophic
- Impaired · Algal growth
- 58 ft max depth
- Public access
- Limited data
Diamond Lake in Douglas County, Oregon has water-quality measurements published by Oregon DEQ, shown here as reported. Chlorophyll-a (algae): 43.4 µg/L.
Diamond Lake is a highly nutrient-loaded hypereutrophic lake in Douglas County, Oregon with an estimated average depth of about 58 feet. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 2 other monitored lakes in Douglas County, Diamond Lake ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, Oregon DEQ, last sampled 2025-09-24. Methodology: how these readings are compared.
Diamond Lake has one public boat landing. Vrbo is where to look for cabins and lake homes around Diamond Lake, and Booking.com and Expedia search hotels near the lake for your dates.
What Diamond Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Camping5 public campgrounds nearby
Swimming conditions
Readings onlyRecreation use not supported
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Diamond Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, oxygen depletion (low DO), pH / acidity. Check local advisories before you swim.
Whether Diamond Lake is safe to swim in today is a call for the Oregon Department of Environmental Quality and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Diamond Lake
These are the measurements Oregon DEQ publishes for Diamond Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
No clarity data. Chlorophyll-a 43.4 µg/L. TSI 68.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | No reading How deep a black-and-white disk stays visible from the surface. Higher is clearer. | |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | 43.4µg/L | Poor GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 68 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Diamond Lake
Answers come straight from the public measurements and survey records on this page.
→ Diamond Lake water level: the live USGS gauge reading
Lake Details
Max depth
~58 ft est.
Public access
Yes
Listed by Oregon DEQ
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Oregon has not published bathymetry for Diamond Lake.
Lake Size & Watershed
Watershed (drainage) area
56 sq mi
HydroLAKES / HydroSHEDS
Surface area
3,000 acres
HydroLAKES / HydroSHEDS
Shoreline
9.1 mi
HydroLAKES / HydroSHEDS
Elevation
5,187 ft
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
- Diamond Lake Campground - M LoopPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Public campgrounds near Diamond Lake
- South Shore Hiker/Biker Camp0.1 km
- South Shore Pavilion0.2 kmReserve
- Broken Arrow0.5 km
- Diamond Lake2.6 kmReserve
- Thielsen View3.7 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
Stays via Stay22
Stays near Diamond Lake
Compare lakeside cabins, hotels, and vacation rentals near Diamond Lake in Douglas County, Oregon — 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 readings cover nutrients and algae, not lodging. Cabins and rentals around Diamond Lake are listed below.
Top-rated places to stay near Diamond Lake
Prices for Oct 30–Nov 1, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a trip? Cabins and lodging at Diamond Lake → · more Oregon lake trips
Follow Diamond Lake’s readings
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Fishing Diamond Lake
Water quality readings over time
2 seasons of samples on record (2024–2025). Calling a direction takes at least 4 years of the same measurement.
Chlorophyll-a
Worsening+17.8 µg/L/yr2 years
EPA Impairment Status
Diamond Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Drinking water, Aquatic life, Fish consumption, Recreation, Other.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit OR_LK_1710030101_02_100181 · Official waterbody report
Nearby Lakes in Douglas County
Frequently asked questions about Diamond Lake
Where is Diamond Lake?
- Diamond Lake is a lake in Douglas County, Oregon. Its water-quality measurements are published by Oregon DEQ and shown on this page as reported.
What is the water quality of Diamond Lake?
- Diamond Lake in Douglas County, Oregon has water-quality measurements published by Oregon DEQ, shown here as reported. Chlorophyll-a (algae): 43.4 µg/L.
Is Diamond Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Diamond Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, oxygen depletion (low DO), pH / acidity. Check local advisories before you swim.
How deep is Diamond Lake?
- No published bathymetric survey covers Diamond Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 58 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 Diamond Lake?
- Diamond Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Diamond Lake Campground - M Loop. Public access is listed as yes.
Can I fish at Diamond Lake?
- Diamond Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Oregon's fish and wildlife agency, so check its current regulations before you go.
Are there campgrounds on Diamond Lake?
- Diamond Lake has 5 public campgrounds from USGS The National Map within 5 km, including South Shore Hiker/Biker Camp, South Shore Pavilion, Broken Arrow, Diamond Lake. 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 Diamond Lake across LakeQuality
4 documented falls within 16.6 mi, nearest Clearwater Falls
2 thermal springs within 18.3 mi, nearest Umpqua Hot Springs
Species activity outlook by water temperature and season
Where to stay at Oregon's top lakes, each with its readings
Oregon's cleanest lakes, ranked on agency measurements
Planning a trip around Crater Lake?
Diamond Lake is about 14 miles from Crater Lake 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 Crater Lake →More lakes in Oregon
Other Lakes in Oregon
Hypereutrophic Lakes in Oregon
Where this data comes from
8 measurements from 1 monitoring station, 2024–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Department of Environmental Quality - State of Oregon
OREGONDEQ8 samples · 2024–2025
Analytical methods
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from 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