Mossyrock Dam Quick Facts
Mossyrock Dam Map
Mossyrock Dam Information
Mossyrock Dam is an arch earth gravity dam located about 23 miles from Toledo, Wa, Lewis, Washington.
The dam, which is on the Cowlitz River, was primarily built for Hydroelectric purposes, but also serves for Recreation and Flood Risk Reduction benefits.
The dam was designed by and commissioned in 1968 and is currently owned by City of Tacoma.
Mossyrock Dam Structure
The Mossyrock Dam is approximately 1,750 feet (533 m) long, 366 feet (112 m) high and has a structural volume of 1,270,000 cubic yards (970,985 cubic metres).
Mossyrock Dam Storage Capacity & Surface Area
The reservoir has a normal storage capacity of 1,700,000 acre-ft (2,096,916 Ml) and maximum capacity of 1,900,000 acre-ft (2,343,612 Ml).
The surface area of the reservoir is acres (0 ha) and the total catchment area is 1,042 square miles (2,699 square kilometres).
Mossyrock Dam Spillway
The dam has a 170 feet (52 m) wide controlled spillway with a maximum discharge capacity of 280000 cubic feet per second (7929 cubic metres per second).
Mossyrock Dam Compared to Five Famous American Dams
Mossyrock Dam Weather
Current Conditions at Mossyrock Dam
| Parameter | Value |
|---|---|
| Current Time | 20:52 |
| Sunrise | 07:27 |
| Sunset | 18:22 |
| Temperature (°F) | 53 |
| Feels Like (°F) | 52 |
| Cloud Coverage (%) | 100 |
| Pressure (inHg) | 1017 |
| Humidity (%) | 97 |
| Wind Speed (mph) | 2 |
| Rain (mm) | 0 |
7-Day Forecast for Mossyrock Dam
| Day | Min Temp (°F) | Max Temp (°F) | Feels Like (°F) | Pressure (inHg) | Humidity (%) | Wind Speed (mph) | Wind Gust (mph) | Wind Dir | Precip Prob (%) | Precip Volume (mm) | Weather |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Today | 52 | 57 | 55 | 1018 | 100 | 3 | 5 | W | 100 | 6 |  |
| Wed | 42 | 52 | 50 | 1017 | 89 | 7 | 15 | W | 100 | 12 | |
| Thu | 41 | 47 | 43 | 1016 | 88 | 5 | 12 | WSW | 100 | 10 | |
| Fri | 43 | 56 | 50 | 1026 | 64 | 4 | 4 | W | 0 | - |  |
| Sat | 48 | 54 | 50 | 1024 | 95 | 5 | 15 | SE | 100 | 3 | |
| Sun | 42 | 55 | 50 | 1020 | 86 | 5 | 8 | W | 100 | 10 | |
| Mon | 41 | 52 | 49 | 1022 | 84 | 3 | 4 | E | 100 | 2 | |
| Tue | 38 | 56 | 49 | 1022 | 62 | 4 | 7 | E | 0 | - |  |
Mossyrock Dam Frequently Asked Questions
Mossyrock Dam is in Washington.
Mossyrock Dam is in Lewis County.
Mossyrock Dam is 366 feet high.
Mossyrock Dam is 1,750 feet long.
More Dams in Lewis County:
Alpina DamCanyon Ferry Dam
Cowlitz Falls Dam
Hauser Dam
Helena Valley Dam
Holter Dam
Mayfield Dam
Mossyrock Dam
Nilan East Dam
Nilan North Dam
Packwood Lake Dam
Rome City Dam
Stonecoal Creek Dam & Reservoir
Willow Creek Bor Mt Dam
More Dams in Washington:
Alder DamBoundary Dam
Box Canyon Dam
Bumping Lake Dam
Castle Lake Debris Dam
Centralia Coal Mine Dam No 3c South
Chaplain Lake North Dam
Chaplain Lake South Dam
Chapman Lake Dam
Chelan Dam
Cle Elum Dam
Coldwater Debris Dam
Conconully Dam
Cowlitz Falls Dam
Culmback Dam
Cushman No 1 Dam
Cushman No 2 Dam
Diablo Dam
Dry Falls Dam
Eagle Lake Dam
Gorge Dam
Grand Coulee Dam
Horse Spring Coulee Dam
Judy Reservoir Dam A
Judy Reservoir Dam B
Kachess Dam
Keechelus Dam
Kinross Gold Kettle River Tailings Dam
La Grande Dam
Leader Lake Dam
Long Lake Dam
Long Lake East Dam
Loon Lake Control Structure Dam
Lower Baker Dam
Masonry Dam
Mayfield Dam
Merwin Dam
Morse Lake Overflow Dike
Moses Lake North Dam
Moses Lake South Dam
Mossyrock Dam
Newman Lake Flood Control Dam
North Dam
Osullivan Dam
Packwood Lake Dam
Padden Lake Dam
Pinto Dam
Priest Rapids Dam
Rock Island Dam
Rocky Reach Dam
Condition Assessment Classification
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. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
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. Investigations and studies are necessary.
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.
Not Available
Dams for which the condition assessment is restricted to approved government users.
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, environment 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.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.
Source: National Inventory of Dams