Diamond Lake
Douglas County, OregonView mapDirections
Nutrients and algae run well above the regional average.
- Hypereutrophic
- Impaired · Algal growth
- #3 of 3 in the county
- 58 ft max depth
- Public access
- Limited data
Diamond Lake in Douglas County, Oregon has a water quality grade of F (Algae-prone). Chlorophyll-a (algae): 43.4 µg/L.
- Max depth
- ~58 ft est.
- Type
- Hypereutrophic
- Chlorophyll-a
- 43.4 µg/L
- Trend
- ↓ Declining
- Public access
- Yes
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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 grade measures nutrients and algae, not lodging — cabins and rentals around Diamond Lake are listed below.
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Diamond Lake is a highly nutrient-loaded hypereutrophic lake in Douglas County, Oregon with an estimated average depth of about 58 feet. Water quality is graded F based on 1 sampling years through 2025. 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. Grade methodology: LakeQuality methodology.
What Diamond Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Camping4 public campgrounds nearby
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. 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.
Water Quality Grade: F (Algae-prone)
No clarity data. Chlorophyll-a 43.4 µg/L. TSI 68. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | 43.4 µg/L | Poor |
| Trophic State Index (TSI) | 68 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Current Conditions
USGS snapshot Sep 7, 2026, 3:30 PM from gauge 14312450 (DIAMOND LAKE NEAR DIAMOND LAKE, OR). Station page ↗ — a live reading replaces this snapshot when the gauge responds. Missing live data is not an all-clear.
→ Diamond Lake water level: the live USGS gauge reading
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~58 ft est. |
| Public Access | Yes |
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
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
- Broken Arrow0.5 km
- Diamond Lake Campground2.6 km
- 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
Fishing Diamond Lake
Water Quality Trend: ↓ Declining
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Chlorophyll-a | ↓ Declining | +17.8 µg/L/yr | 2 |
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
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit OR_LK_1710030101_02_100181 · Official waterbody report
County Ranking
Ranked #3 of 3 lakes in Douglas County
Nearby Lakes in Douglas County
Frequently asked questions about Diamond Lake
Where is Diamond Lake?
- Diamond Lake is a lake in Douglas County, Oregon. LakeQuality grades it F for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Diamond Lake?
- Diamond Lake in Douglas County, Oregon has a water quality grade of F (Algae-prone). Chlorophyll-a (algae): 43.4 µg/L.
Is Diamond Lake safe to swim in?
- The F is nutrients and algae, 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.
What is the water level at Diamond Lake?
- The USGS snapshot on this page for Diamond Lake is 5184.15 ft of water-surface elevation, recorded Sep 7, 2026, 3:30 PM at gauge 14312450. Current Conditions hydrates a live NWIS reading from that same station when the gauge responds. A missed live fetch is not an all-clear.
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.
Are there campgrounds on Diamond Lake?
- Diamond Lake has 4 public campgrounds from USGS The National Map within 5 km, including South Shore Hiker/Biker Camp, Broken Arrow, Diamond Lake Campground, Thielsen View. 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 grade
Very high nutrients, dense algae, poor clarity
Oregon's cleanest and most-polluted lakes, ranked
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 Oregon Lake Rankings
Other Grade F 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)
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