Foster Lake
Linn County, Oregon1,220 acresView mapDirections
Oregon DEQ publishes the water-quality measurements for Foster Lake. Here is what has been measured.
- Mesotrophic
- Impaired · Temperature
- Public access
- Limited data
Foster Lake in Linn County, Oregon has water-quality measurements published by Oregon DEQ, shown here as reported. Chlorophyll-a (algae): 2.4 µg/L. Surface area: 1220 acres.
Foster Lake is a 1,220-acre mesotrophic lake in Linn County, Oregon. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 2 public boat landings. Compared to the 1 other monitored lakes in Linn County, Foster Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Oregon DEQ, last sampled 2025-10-16. Methodology: how these readings are compared.
Foster Lake covers about 1,200 acres in Linn County. It has 2 public boat landings, so a lakefront rental is not the only way to get a boat on the water. If you are planning to stay, you can search lake houses and cabins around Foster Lake on Vrbo, or look for a hotel room near the lake on Booking.com or Expedia.
What Foster Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch2 documented ramps
- Big water1,220 acres
Swimming conditions
Readings onlyLimited data
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. Foster Lake is listed impaired under Clean Water Act §303(d) (IR 5) for temperature. Check local advisories before you swim.
Whether Foster 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 Foster Lake
These are the measurements Oregon DEQ publishes for Foster 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. Chlorophyll-a 2.4 µg/L. TSI 39.
| 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 | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | 2.4µg/L | Fair GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 39 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Foster Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
1,220 acres
Public access
Yes
Listed by Oregon DEQ
No bathymetric survey has been published for Foster Lake, so its depth is not documented here.
Recreation & Access
- Calkins ParkPublic
- Sunnyside ParkPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Foster Lake
Compare lakeside cabins, hotels, and vacation rentals near Foster Lake in Linn 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.
Top-rated places to stay near Foster Lake
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Fishing Foster Lake
Water quality readings over time
2 seasons of samples on record (2024–2025). Calling a direction takes at least 4 years of the same measurement.
Chlorophyll-a
Improving-0.3 µg/L/yr2 years
Reservoir Info (USACE NID)
Foster Lake is a man-made reservoir impounded by the Foster Dam (completed 1967), built primarily for flood risk reduction on the South Santiam River; rockfill-type dam, 126 ft tall and 4,800 ft long.
- Surface area
- 1,220 ac
- Normal storage
- 56,000 ac-ft
- Max storage
- 61,000 ac-ft
- Drainage area
- 494 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 OR00012 · Operator website
EPA Impairment Status
Foster 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.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit OR_LK_1709000604_02_100772 · Official waterbody report
Nearby Lakes in Linn County
Frequently asked questions about Foster Lake
Where is Foster Lake?
- Foster Lake is a lake in Linn County, Oregon. Its water-quality measurements are published by Oregon DEQ and shown on this page as reported.
What is the water quality of Foster Lake?
- Foster Lake in Linn County, Oregon has water-quality measurements published by Oregon DEQ, shown here as reported. Chlorophyll-a (algae): 2.4 µg/L. Surface area: 1220 acres.
Is Foster Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Foster Lake is listed impaired under Clean Water Act §303(d) (IR 5) for temperature. Check local advisories before you swim.
Are there boat ramps on Foster Lake?
- Foster Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Calkins Park, Sunnyside Park. Public access is listed as yes.
Can I fish at Foster Lake?
- Foster Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Oregon's fish and wildlife agency, so check its current regulations before you go.
Explore Foster Lake across LakeQuality
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Where this data comes from
8 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
OREGONDEQ8 samples · 2024–2025
Analytical methods
- 10200 H ~ Chlorophyll a-b-c Determination
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
Named boat-access points from the USGS National Boat Ramps inventory