Green Peter Lake
Linn County, Oregon3,720 acresView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
- Oligotrophic
- Impaired · Temperature
- #1 of 2 in the county
- 51 ft max depth
- Public access
- Limited data
Green Peter Lake in Linn County, Oregon has a water quality grade of A (Excellent). Chlorophyll-a (algae): 1.4 µg/L. Surface area: 3720 acres.
- Max depth
- ~51 ft est.
- Area
- 3,720 acres
- Type
- Oligotrophic
- Chlorophyll-a
- 1.4 µg/L
- Trend
- ↑ Improving
- Public access
- Yes
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Watch Green Peter Lake’s letter
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Green Peter Lake is a 3,720-acre cold, clear oligotrophic lake in Linn County, Oregon with an estimated average depth of about 51 feet. Water quality is graded A based on 1 sampling years through 2025. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 3 public boat landings. Compared to the 1 other monitored lakes in Linn County, Green Peter Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Oregon DEQ, last sampled 2025-08-06. Grade methodology: LakeQuality methodology.
What Green Peter Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch3 documented ramps
- Big water3,720 acres
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 A is nutrients and algae, not a swimming clearance. Green Peter Lake is listed impaired under Clean Water Act §303(d) (IR 5) for temperature. Check local advisories before you swim.
Water Quality Grade: A (Excellent)
No clarity data. Chlorophyll-a 1.4 µg/L. TSI 34. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | 1.4 µg/L | Good |
| Trophic State Index (TSI) | 34 | Oligotrophic |
Low nutrients, clear water. The letter is not a swimming clearance.
Current Conditions
USGS snapshot Sep 7, 2026, 3:50 PM from gauge 14186100 (GREEN PETER LAKE NEAR FOSTER, OR). Station page ↗ — a live reading replaces this snapshot when the gauge responds. Missing live data is not an all-clear.
→ Green Peter Lake water level: the live USGS gauge reading
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~51 ft est. |
| Surface Area | 3,720 acres |
| 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 Green Peter 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
- Whitcomb Creek County ParkPublic
- Thistle CreekPublic
- Billings ParkPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Green Peter Lake
Water Quality Trend: ↑ Improving
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Chlorophyll-a | ↑ Improving | -0.9 µg/L/yr | 2 |
Reservoir Info (USACE NID)
Green Peter Lake is a man-made reservoir impounded by the Green Peter Dam (completed 1967), built primarily for flood risk reduction on the Middle Santiam River; gravity-type dam, 378 ft tall and 1,517 ft long.
- Surface area
- 3,720 ac
- Normal storage
- 160,000 ac-ft
- Max storage
- 430,000 ac-ft
- Drainage area
- 277 sq mi
- Hazard class
- High
- Owner
- USACE - Portland District
All listed purposes: Flood Risk Reduction;Other;Irrigation;Navigation;Recreation;Hydroelectric.
Source: USACE National Inventory of Dams, NID ID OR00010 · Operator website
EPA Impairment Status
Green Peter 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_1709000603_02_100771 · Official waterbody report
County Ranking
Ranked #1 of 2 lakes in Linn County
Nearby Lakes in Linn County
Frequently asked questions about Green Peter Lake
Where is Green Peter Lake?
- Green Peter Lake is a lake in Linn County, Oregon. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Green Peter Lake?
- Green Peter Lake in Linn County, Oregon has a water quality grade of A (Excellent). Chlorophyll-a (algae): 1.4 µg/L. Surface area: 3720 acres.
Is Green Peter Lake safe to swim in?
- The A is nutrients and algae, not a swimming clearance. Green Peter Lake is listed impaired under Clean Water Act §303(d) (IR 5) for temperature. Check local advisories before you swim.
How deep is Green Peter Lake?
- No published bathymetric survey covers Green Peter Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 51 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 3720 acres.
What is the water level at Green Peter Lake?
- The USGS snapshot on this page for Green Peter Lake is 911.36 ft of water-surface elevation, recorded Sep 7, 2026, 3:50 PM at gauge 14186100. 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 Green Peter Lake?
- Green Peter Lake has 3 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Whitcomb Creek County Park, Thistle Creek, Billings Park. Public access is listed as yes.
Explore Green Peter Lake across LakeQuality
Depth, room, public access, and the state wake-sport rules
Species activity outlook by water temperature and season
Where to stay at Oregon's top lakes, each with its grade
Low nutrients, clear water. The letter is not a swimming clearance.
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Where this data comes from
6 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
OREGONDEQ6 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