Mount St. Helens Sediment Retention Structure dam
Mount St. Helens Sediment Retention Structure
The Mount St. Helens Sediment Retention Structure, located in Toutle, Washington, was completed in 1988 by the US Army Corps of Engineers to primarily reduce flood risks in the area. This Earth-type dam stands at a height of 186 feet, with a hydraulic height of 180 feet and a structural height of 239 feet. It spans 1800 feet in length and has a dam volume of 228,000 cubic feet. The dam is situated on the North Fork Toutle River and has a spillway width of 400 feet to manage a maximum discharge of 228,000 cubic feet per second.
The risk assessment for the Mount St. Helens Sediment Retention Structure indicates a low hazard potential, with routine evaluations ensuring the dam's safety and functionality. The US Army Corps of Engineers continues to monitor and assess the structure's condition, conducting regular inspections and equipping it with instrumentation for performance monitoring. An Emergency Action Plan is in place to guide response procedures in case of an emergency, and the Corps engages in emergency exercises with local stakeholders to enhance community awareness of flood risks. Overall, the structure's risk management measures are robust, with plans for an updated risk assessment in 2022 to address evolving earthquake and flood hazards.
In summary, the Mount St. Helens Sediment Retention Structure serves as a crucial flood risk reduction measure on the North Fork Toutle River in Washington. With its high hazard potential classification and routine risk assessments, the US Army Corps of Engineers ensures the safety and functionality of the dam. Through ongoing monitoring, emergency response planning, and community outreach efforts, the Corps remains committed to safeguarding the area from potential risks associated with the dam.
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 Mount St. Helens Sediment Retention Structure -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Nf Toutle River Below Srs Near Kid Valley | 789 cfs | → |
| South Fork Toutle River At Toutle | 868 cfs | → |
| Cowlitz River Below Mayfield Dam | 4,620 cfs | → |
| Toutle River At Tower Road Near Silver Lake | 1,360 cfs | → |
| South Fork Newaukum River Near Onalaska | 182 cfs | → |
| Tilton River Ab Bear Canyon Creek Near Cinebar | 353 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Mount St. Helens Sediment Retention Structure.
Boat launches
- Kerr Road 500, Silver Lake
- Mayfield Lake Park Campground Boat Launch
- Ajlune Road Lewis County
- Mcdougall Drive 136, Mossyrock
- Buckley Road 298, Toledo
- Spirit Lake Highway Cowlitz County
Campgrounds
- Kid Valley Campground
- Mayfield Lake - Tacoma Power
- Mossyrock Park - Tacoma Power
- Main Campground
- Riffe Lake Campground
- S'Mores Loop
Paddle runs
- Headwaters In Sw1/4 Sec 28, T9n, R5e To Mount St. Helens National Volcanic Monument Boundary
- Mount St. Helens National Volcanic Monument Boundary To Mount St. Helens National Volcanic Boundary In Sw 1/4 Of Sec 32, T11n, R5e
- Mount St. Helens National Volcanic Monument Boundary To To Point River Reenters Mshnvm In Se 1/4 Of Sec 11, T10n, R5e
- Headwaters In Se1/4 Of Sec 31, T10n, R6e To Mount St. Helens National Volcanic Monument Boundary
- Goat Rocks Wilderness Bounday To Cowlitz Falls Ferc Project Boundary In Ne1/4 Of Nw1/4 Of Sec 4, T11n, R6e
- (Upper Muddy Segment) Headwaters In Se1/4 Of Sec 10, T8n, R5e To Conflence With Smith Creek
Track Mount St. Helens Sediment Retention Structure 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 Mount St. Helens Sediment Retention Structure
Where does the data for Mount St. Helens Sediment Retention Structure 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 High 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 Mount St. Helens Sediment Retention Structure.