Phillips Lake
Baker County, Oregon2,235 acresView mapDirections
Not enough samples to grade — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). No letter yet. Here is what we do have.
- Impaired · Mercury
- Public access
- Limited data
Phillips Lake in Baker County, Oregon is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 5.9 ft visibility. Phosphorus: 17.5 µg/L. Chlorophyll-a (algae): 2.1 µg/L. Surface area: 2235 acres.
- Clarity
- 5.9 ft
- Area
- 2,235 acres
- Phosphorus
- 17.5 µg/L
- Chlorophyll-a
- 2.1 µg/L
- Public access
- Yes
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Watch Phillips Lake’s letter
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Why Phillips Lake has no grade
We grade a lake only when the monitoring record supports a letter: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Phillips Lake, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). Sampling here has recorded water clarity, phosphorus and algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by Oregon DEQ and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Phillips Lake is a 2,235-acre lake in Baker County, Oregon. Limited fish-species data available. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, Oregon DEQ, last sampled 2022-06-08. Grade methodology: LakeQuality methodology.
What Phillips Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Big water2,235 acres
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Phillips Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, oxygen depletion (low DO), toxic inorganics. Check local advisories before you swim.
Water quality measurements for Phillips Lake
These readings exist but are not enough for an A–F grade — see why.
Murky, only visible to about 5.9 ft. Phosphorus 17.5 µg/L. Chlorophyll-a 2.1 µg/L. TSI 45.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5.9 ft | Not graded |
| Phosphorus | 17.5 µg/L | Not graded |
| Chlorophyll-a (Algae) | 2.1 µg/L | Not graded |
| Trophic State Index (TSI) | 45 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 2,235 acres |
| Public Access | Yes |
No bathymetric survey has been published for Phillips Lake, so its depth is not documented here.
Recreation & Access
- MasonPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Phillips Lake
Reservoir Info (USACE NID)
Phillips Lake is a man-made reservoir impounded by the Mason Dam (completed 1968), built primarily for flood risk reduction on the Powder River; rockfill-type dam, 173 ft tall and 895 ft long.
- Surface area
- 2,235 ac
- Normal storage
- 78,500 ac-ft
- Max storage
- 95,500 ac-ft
- Drainage area
- 164.76 sq mi
- Hazard class
- High
- Owner
- BUREAU OF RECLAMATION
All listed purposes: Flood Risk Reduction;Irrigation.
Source: USACE National Inventory of Dams, NID ID OR00577 · Operator website · Matched by proximity (0.72 km)
EPA Impairment Status
Phillips 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_1705020301_05_100588 · Official waterbody report
Graded lakes near Phillips Lake
Phillips Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Baker County
Frequently asked questions about Phillips Lake
Where is Phillips Lake?
- Phillips Lake is a lake in Baker County, Oregon. LakeQuality has not rated this lake (UNRATED) — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years).
What is the water quality grade for Phillips Lake?
- Phillips Lake in Baker County, Oregon is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 5.9 ft visibility. Phosphorus: 17.5 µg/L. Chlorophyll-a (algae): 2.1 µg/L. Surface area: 2235 acres.
Is Phillips Lake safe to swim in?
- The letter is not a swimming clearance. Phillips Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, oxygen depletion (low DO), toxic inorganics. Check local advisories before you swim.
Are there boat ramps on Phillips Lake?
- Phillips Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Mason. Public access is listed as yes.
Explore Phillips Lake across LakeQuality
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Where this data comes from
7 measurements from 1 monitoring station, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Bureau of Reclamation
1119USBR_WQX7 samples · 2022
Analytical methods
- Zebra/Quagga Mussel APHA 10200G Modified
- Phosphorus by Single Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- Turbidity by Nephelometry
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