Siltcoos Lake
Lane County, Oregon3,585 acresView mapDirections
Oregon DEQ publishes the water-quality measurements for Siltcoos Lake. Here is what has been measured.
- Mesotrophic
- Impaired · Algal growth
- 43 ft max depth
- Public access
- Limited data
Siltcoos Lake in Lane County, Oregon has water-quality measurements published by Oregon DEQ, shown here as reported. Chlorophyll-a (algae): 5.4 µg/L. Surface area: 3585 acres.
Siltcoos Lake is a 3,585-acre mesotrophic lake in Lane County, Oregon with an estimated average depth of about 43 feet. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 4 public boat landings. Compared to the 2 other monitored lakes in Lane County, Siltcoos Lake ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, Oregon DEQ, last sampled 2025-10-16. Methodology: how these readings are compared.
What Siltcoos Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch4 documented ramps
- Camping6 public campgrounds nearby
- Big water3,585 acres
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. Siltcoos Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth. Check local advisories before you swim.
Whether Siltcoos 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 Siltcoos Lake
These are the measurements Oregon DEQ publishes for Siltcoos 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 5.4 µg/L. TSI 47.
| 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) | 5.4µg/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. | 47 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Siltcoos Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
~43 ft est.
Surface area
3,585 acres
Public access
Yes
Listed by Oregon DEQ
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Oregon has not published bathymetry for Siltcoos Lake.
Lake Size & Watershed
Watershed (drainage) area
69 sq mi
HydroLAKES / HydroSHEDS
Shoreline
26.1 mi
HydroLAKES / HydroSHEDS
Elevation
13 ft
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
- Westlake LandingPublic
- Honeyman Memorial State ParkPublic
- Fish Mill LodgesSemi-private
- Darlings ResortSemi-private
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Public campgrounds near Siltcoos Lake
- Tyee Campground0.6 km
- Tyee Campground - Oregon Dunes0.6 kmReserve
- Driftwood2.4 kmReserve
- Lagoon Campground2.4 km
- Driftwood Ii2.9 km
- Siltcoos Sand Camping3.0 kmReserve
Nearest public campgrounds in the USGS National Map inventory, within about 3 miles. An empty list means USGS records no campground that close, which is not the same as camping being unavailable. Where the source gives an official reservation link, it is used; the cabin and hotel search does not cover campsites. More camping lakes
Stays via Stay22
Stays near Siltcoos Lake
Compare lakeside cabins, hotels, and vacation rentals near Siltcoos Lake in Lane 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 Siltcoos Lake are listed below.
Top-rated places to stay near Siltcoos Lake
Prices for Oct 30–Nov 1, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a trip? Cabins and lodging at Siltcoos Lake → · more Oregon lake trips
Follow Siltcoos Lake’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fishing Siltcoos 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-3.6 µg/L/yr2 years
Reservoir Info (USACE NID)
Siltcoos Lake is a man-made reservoir impounded by the Siltcoos Lake (completed 1964), built primarily for other on the Siltcoos River; gravity-type dam, 14 ft tall and 130 ft long.
- Surface area
- 3,585 ac
- Normal storage
- 15,070 ac-ft
- Max storage
- 15,070 ac-ft
- Drainage area
- 50 sq mi
- Hazard class
- Low
- Owner
- INDUSTRIAL HARBOR USA
Source: USACE National Inventory of Dams, NID ID OR00358 · Operator website
EPA Impairment Status
Siltcoos 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, Fish consumption, Recreation, Other.
Source: EPA ATTAINS assessment unit OR_LK_1710020701_02_100176 · Official waterbody report
Nearby Lakes in Lane County
Frequently asked questions about Siltcoos Lake
Where is Siltcoos Lake?
- Siltcoos Lake is a lake in Lane County, Oregon. Its water-quality measurements are published by Oregon DEQ and shown on this page as reported.
What is the water quality of Siltcoos Lake?
- Siltcoos Lake in Lane County, Oregon has water-quality measurements published by Oregon DEQ, shown here as reported. Chlorophyll-a (algae): 5.4 µg/L. Surface area: 3585 acres.
Is Siltcoos Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Siltcoos Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth. Check local advisories before you swim.
How deep is Siltcoos Lake?
- No published bathymetric survey covers Siltcoos Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 43 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 3585 acres.
Are there boat ramps on Siltcoos Lake?
- Siltcoos Lake has 4 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Westlake Landing, Honeyman Memorial State Park, Fish Mill Lodges, Darlings Resort. Public access is listed as yes.
Can I fish at Siltcoos Lake?
- Siltcoos Lake has 4 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.
Are there campgrounds on Siltcoos Lake?
- Siltcoos Lake has 6 public campgrounds from USGS The National Map within 5 km, including Tyee Campground, Tyee Campground - Oregon Dunes, Driftwood, Lagoon Campground. This is a location join, not a booking. Cabins and hotels are listed separately; campsite reservations use the official link when the source provides one.
Explore Siltcoos Lake across LakeQuality
More lakes in Oregon
Other Lakes in Oregon
Mesotrophic Lakes in Oregon
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory
Public campgrounds from USGS The National Map Structures, within about 3 miles