Deschutes River Arm Lake
Jefferson County, OregonView mapDirections
Oregon DEQ publishes the water-quality measurements for Deschutes River Arm Lake. Here is what has been measured.
- Mesotrophic
- Impaired · Algal growth
Deschutes River Arm Lake in Jefferson County, Oregon has water-quality measurements published by Oregon DEQ, shown here as reported. Water clarity: 4.6 ft visibility. Phosphorus: 60 µg/L. Chlorophyll-a (algae): 4.4 µg/L.
Deschutes River Arm Lake is a mesotrophic lake in Jefferson County, Oregon. Overall water quality is improving over recent sampling years. Compared to the 13 other monitored lakes in Jefferson County, Deschutes River Arm Lake ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, Oregon DEQ, last sampled 2025-09-10. Methodology: how these readings are compared.
Swimming conditions
Readings onlyElevated nutrients
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. Deschutes River Arm Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, hydrologic alteration, pH / acidity. Check local advisories before you swim.
Whether Deschutes 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 Deschutes River Arm Lake
These are the measurements Oregon DEQ publishes for Deschutes River Arm Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 4.6 ft. Phosphorus 60 µg/L. Chlorophyll-a 4.4 µg/L. TSI 54.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 4.6ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 60µg/L | Measured, not scored The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. |
| Chlorophyll-a (algae) | 4.4µg/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. | 54 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Deschutes River Arm Lake
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Stays via Stay22
Stays near Deschutes River Arm Lake
Compare lakeside cabins, hotels, and vacation rentals near Deschutes 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 Deschutes River Arm Lake are listed below.
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Fishing Deschutes River Arm Lake
Water quality readings over time
3 seasons of samples on record (2021–2025). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Improving2 years
Phosphorus
Improving-2.5 µg/L/yr2 years
Chlorophyll-a
Worsening+2.63 µg/L/yr3 years
EPA Impairment Status
Deschutes 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: Aquatic life, Other.
Source: EPA ATTAINS assessment unit OR_LK_1707030111_02_100151 · Official waterbody report
Nearby Lakes in Jefferson County
Frequently asked questions about Deschutes River Arm Lake
Where is Deschutes River Arm Lake?
- Deschutes 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 Deschutes River Arm Lake?
- Deschutes River Arm Lake in Jefferson County, Oregon has water-quality measurements published by Oregon DEQ, shown here as reported. Water clarity: 4.6 ft visibility. Phosphorus: 60 µg/L. Chlorophyll-a (algae): 4.4 µg/L.
Is Deschutes River Arm Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Deschutes River Arm Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, hydrologic alteration, pH / acidity. Check local advisories before you swim.
Explore Deschutes River Arm Lake across LakeQuality
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Species activity outlook by water temperature and season
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Where this data comes from
100 measurements from 1 monitoring station, 2021–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Department of Environmental Quality - State of Oregon
OREGONDEQ100 samples · 2021–2025
Analytical methods
- 2012 National Lakes Assessment Field Operations Manual
- 4500 P E ~ Phosphorus in Water by Colorimetry- Ascorbic Acid Method
- 10200 H ~ Chlorophyll a-b-c Determination
- 2130 B ~ Nephelometric Method
- Standard Test Method for Determination of Turbidity Above 1 Turbidity Unit (TU) in Static Mode
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