Agency Lake South
Klamath County, OregonView mapDirections
Nutrients and algae run well above the regional average.
- Hypereutrophic
- Impaired · Algal growth
- #12 of 17 in the county
- Public access
Agency Lake South in Klamath County, Oregon has a water quality grade of F (Algae-prone). Phosphorus: 110 µg/L. Chlorophyll-a (algae): 61.6 µg/L.
- Type
- Hypereutrophic
- Phosphorus
- 110 µg/L
- Chlorophyll-a
- 61.6 µg/L
- Trend
- ↓ Declining
- Public access
- Yes
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Stays near Agency Lake South
Compare lakeside cabins, hotels, and vacation rentals near Agency Lake South in Klamath 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 Agency Lake South are listed below.
Top-rated places to stay near Agency Lake South
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Watch Agency Lake South’s letter
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Agency Lake South is a highly nutrient-loaded hypereutrophic lake in Klamath County, Oregon. Water quality is graded F based on 2 sampling years through 2023. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 6 public boat landings. Compared to the 16 other monitored lakes in Klamath County, Agency Lake South ranks #12 for water quality.
Source: EPA Water Quality Portal sampling records, Oregon DEQ, last sampled 2023-09-25. Grade methodology: LakeQuality methodology.
What Agency Lake South is good for
From access and monitoring records, not editorial picks.
- Boat launch6 documented ramps
Swimming Safety
Grade onlyAlgae risk
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. Agency Lake South 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. Phosphorus 110 µg/L. Chlorophyll-a 61.6 µg/L. TSI 71. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 110 µg/L | Poor |
| Chlorophyll-a (Algae) | 61.6 µg/L | Poor |
| Trophic State Index (TSI) | 71 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Recreation & Access
- Henzel ParkPublic
- Malone SpringsPublic
- Chiloquin AccessPublic
- Petric ParkPublic
- Waterwheel CampgroundSemi-private
- Agency Lake ResortSemi-private
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Agency Lake South
Water Quality Trend: ↓ Declining
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Phosphorus | ↓ Declining | +34 µg/L/yr | 4 |
| Chlorophyll-a | → Stable | -0.79 µg/L/yr | 4 |
EPA Impairment Status
Agency Lake South 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_1801020303_05_100374 · Official waterbody report · Matched by proximity (2.41 km)
County Ranking
Ranked #12 of 17 lakes in Klamath County
Nearby Lakes in Klamath County
Frequently asked questions about Agency Lake South
Where is Agency Lake South?
- Agency Lake South is a lake in Klamath County, Oregon. LakeQuality grades it F for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Agency Lake South?
- Agency Lake South in Klamath County, Oregon has a water quality grade of F (Algae-prone). Phosphorus: 110 µg/L. Chlorophyll-a (algae): 61.6 µg/L.
Is Agency Lake South safe to swim in?
- The F is nutrients and algae, not a swimming clearance. Agency Lake South 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.
Are there boat ramps on Agency Lake South?
- Agency Lake South has 6 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Henzel Park, Malone Springs, Chiloquin Access, Petric Park, among others. Public access is listed as yes.
Explore Agency Lake South across LakeQuality
Planning a trip around Crater Lake?
Agency Lake South is about 30 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
83 measurements from 1 monitoring station, 2020–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- USGS Oregon Water Science Center
USGS-OR83 samples · 2020–2023
Analytical methods
- Nutrients, wu, WCA,persulfate,CF
- Chlorophyll a, phytoplankton
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
Named boat-access points from the USGS National Boat Ramps inventory