Mayfield dam
Mayfield
Mayfield, located in Lewis, Washington, is a public utility owned hydroelectric dam on the Cowlitz River. Built in 1963 by Harza Engineering Co., this arch-type dam stands at a height of 200 feet and has a structural height of 250 feet. With a storage capacity of 184,194 acre-feet and a normal storage of 133,718 acre-feet, Mayfield serves multiple purposes including hydroelectric power generation and recreation.
The dam's controlled spillway has a width of 205 feet, and it is equipped with five Tainter radial gates for water release. Mayfield's hazard potential is rated as high, with a very high risk assessment score of 1. Despite its age, the dam's condition assessment is currently not available. The Federal Energy Regulatory Commission oversees its regulatory and inspection activities, ensuring its safe operation and maintenance.
Mayfield's strategic location and significant storage capacity make it a vital water resource in the region. Its impressive hydraulic height of 230 feet contributes to its efficient power generation capabilities. With its rich history and crucial role in water management and energy production, Mayfield remains a fascinating site for water resource and climate enthusiasts to explore and learn from.
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 Mayfield -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Cowlitz River Below Mayfield Dam | 4,600 cfs | → |
| South Fork Newaukum River Near Onalaska | 182 cfs | → |
| Tilton River Ab Bear Canyon Creek Near Cinebar | 323 cfs | → |
| Nf Toutle River Below Srs Near Kid Valley | 766 cfs | → |
| South Fork Toutle River At Toutle | 868 cfs | → |
| Nf Newaukum River Above Bear Creek Near Forest | 73 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Mayfield.
Boat launches
- Mayfield Lake Park Campground Boat Launch
- Ajlune Road Lewis County
- Mcdougall Drive 136, Mossyrock
- Buckley Road 298, Toledo
- Front Street Toledo
- Interstate 5, Toledo
Campgrounds
- Mayfield Lake - Tacoma Power
- Ike Kinswa State Park
- Mossyrock Park - Tacoma Power
- Main Campground
- S'Mores Loop
- Riffe Lake Campground
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
- Goat Rocks Wilderness Bounday To Cowlitz Falls Ferc Project Boundary In Ne1/4 Of Nw1/4 Of Sec 4, T11n, R6e
- Headwaters In Se1/4 Of Sec 31, T10n, R6e To Mount St. Helens National Volcanic Monument Boundary
- (Upper Muddy Segment) Headwaters In Se1/4 Of Sec 10, T8n, R5e To Conflence With Smith Creek
Track Mayfield 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 Mayfield
Where does the data for Mayfield 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 Mayfield.