Trillium Lake dam
Trillium Lake
Trillium Lake, located in Clackamas, Oregon, is a state-regulated water resource known for its stunning natural beauty and recreational opportunities. Managed by the Oregon Department of Fish and Wildlife, this reservoir was completed in 1960 and serves primarily for recreation purposes. The dam, an earth structure standing at 21 feet tall and spanning 985 feet in length, creates a reservoir with a maximum storage capacity of 380 acre-feet and a normal storage of 353 acre-feet. With a surface area of 65 acres and a drainage area of 0.87 square miles, Trillium Lake offers a picturesque setting for activities such as fishing, boating, and hiking.
Surrounded by the serene wilderness of the Welch's area and fed by Mud Creek, Trillium Lake is a popular destination for outdoor enthusiasts and nature lovers alike. The dam's spillway type and width are not specified, but it is equipped with a slide (sluice gate) as its outlet gate. Despite its low hazard potential and undetermined condition assessment, the dam is inspected regularly, with the last inspection conducted in June 2019. Trillium Lake's proximity to Portland District and its association with various regulatory agencies ensure that it is managed and maintained in compliance with state regulations, providing a safe and enjoyable environment for visitors to appreciate the intersection of water resources and climate in this idyllic setting.
Dam data reference
Condition Assessment
- Satisfactory
- No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
- Fair
- No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action.
- Poor
- A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency.
- Unsatisfactory
- A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
- Not Rated
- The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Hazard Potential Classification
- High
- Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
- Significant
- Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environmental damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
- Low
- Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
- Undetermined
- Dams for which a downstream hazard potential has not been designated or is not provided.
Plan around the weather
Same NOAA / yr.no feed Snoflo's iOS app uses. Watch the precipitation column on the meteogram -- rain on the basin upstream typically lifts inflow 24-72 hours later.
Next 5 days, hour by hour
Temperature line with weather symbols on top, snow + rain accumulation as columns, humidity as a dotted line.
5-day forecast table
Every 3 hours, broken out across temperature, snow, rain, humidity, and wind. Each cell is colour-coded relative to the column min/max.
| Time | Condition | Temp (°F) | Snow (in) | Rain (in) | Humidity (%) | Wind (mps) | Wind dir |
|---|---|---|---|---|---|---|---|
| Loading detailed forecast… | |||||||
15-day temperature & precipitation
Daily temperatures, snow, and rain projected over the next two weeks.
Nearby streamflow gauges
USGS streamgauges around Trillium Lake -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Oak Grove Fork Near Government Camp | 71 cfs | → |
| Blazed Alder Creek Near Rhododendron | 18 cfs | → |
| Bull Run River At Lower Flume Nr Brightwood | 24 cfs | → |
| Oak Grove Fork Above Powerplant Intake | 296 cfs | → |
| Clackamas River Above Three Lynx Creek | 931 cfs | → |
| Oak Grove Fork At Ripplebrook Campground | 111 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Trillium Lake.
Boat launches
- Clear Lake Campground
- Badger Lake
- Gone Creek Campground
- Hoodview Campground
- Laurance Lake
- Lost Lake Resort
Campgrounds
- Trillium Lake Campground
- Still Creek Campground
- Devil's Half Acre Campground
- Frog Lake Campground
- Alpine Campground
- Grindstone Campground
Fishing spots
- Whittakers Pond
- Savannah River
- Little Black River
- Magnolia Springs State Park Lake
- Watson Pond
- Fishing From Bonito Bridge
Track Trillium Lake in the Snoflo app
Save this dam as a favorite and get the local NOAA / yr.no forecast plus regional flow context wherever you are.
About Trillium Lake
Where does the data for Trillium Lake come from?
Structural and regulatory data come from the U.S. Army Corps of Engineers' National Inventory of Dams (NID). Weather forecast comes from NOAA / yr.no -- the same feed Snoflo's iOS app uses.
How often is the report updated?
NID structural data refreshes annually as the Corps publishes updated assessments. The weather forecast refreshes throughout the day.
What does the Low hazard rating mean?
The Corps of Engineers' hazard potential classification grades probable consequences if the dam fails: High = probable loss of human life; Significant = no probable loss of human life but possible economic loss / environmental damage; Low = no probable loss of human life, only minor economic / environmental losses. See the Dam Data Reference card above for the full definitions.
What's "% of normal"?
The current storage value compared to the historical average storage on this calendar day. 100% = right on average; values above 100% mean above-normal storage (wet year); values below mean below-normal (dry year or drought).
Can I get alerts when storage crosses a threshold?
Yes -- alerts are managed in the Snoflo iOS app. Favorite this dam, set a threshold, and you'll get a push the moment conditions cross.
Other water bodies near here
Snoflo-tracked reservoirs and dams within driving distance of Trillium Lake.