Crooked River Arm Lake
Jefferson County, OregonView mapDirections
Oregon DEQ publishes the water-quality measurements for Crooked River Arm Lake. Here is what has been measured.
- Eutrophic
- Impaired · Algal growth
- Limited data
Crooked River Arm Lake in Jefferson County, Oregon has water-quality measurements published by Oregon DEQ, shown here as reported. Phosphorus: 60 µg/L. Chlorophyll-a (algae): 24.6 µg/L.
Crooked River Arm Lake is a productive, nutrient-rich eutrophic lake in Jefferson County, Oregon. Compared to the 13 other monitored lakes in Jefferson County, Crooked River Arm Lake ranks #7 for water quality.
Source: EPA Water Quality Portal sampling records, Oregon DEQ, last sampled 2021-10-20. Methodology: how these readings are compared.
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. Crooked River Arm Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, hydrologic alteration. Check local advisories before you swim.
Whether Crooked River Arm 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 Crooked River Arm Lake
These are the measurements Oregon DEQ publishes for Crooked River Arm 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. Phosphorus 60 µg/L. Chlorophyll-a 24.6 µg/L. TSI 63.
| 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 | 60µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 24.6µg/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. | 63 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
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Stays near Crooked River Arm Lake
Compare lakeside cabins, hotels, and vacation rentals near Crooked River Arm Lake in Jefferson 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 Crooked River Arm Lake are listed below.
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Fishing Crooked River Arm Lake
EPA Impairment Status
Crooked River Arm 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.
Source: EPA ATTAINS assessment unit OR_LK_1707030511_02_100117 · Official waterbody report
Nearby Lakes in Jefferson County
Frequently asked questions about Crooked River Arm Lake
Where is Crooked River Arm Lake?
- Crooked River Arm Lake is a lake in Jefferson County, Oregon. Its water-quality measurements are published by Oregon DEQ and shown on this page as reported.
What is the water quality of Crooked River Arm Lake?
- Crooked River Arm Lake in Jefferson County, Oregon has water-quality measurements published by Oregon DEQ, shown here as reported. Phosphorus: 60 µg/L. Chlorophyll-a (algae): 24.6 µg/L.
Is Crooked River Arm Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Crooked River Arm Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, hydrologic alteration. Check local advisories before you swim.
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Where this data comes from
30 measurements from 1 monitoring station, 2021. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Department of Environmental Quality - State of Oregon
OREGONDEQ30 samples · 2021
Analytical methods
- 4500 P E ~ Phosphorus in Water by Colorimetry- Ascorbic Acid Method
- 10200 H ~ Chlorophyll a-b-c Determination
- 2130 B ~ Nephelometric Method
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