It was created in the 1960s as part of the Mossyrock Dam hydroelectric project, which aimed to provide electricity to the region. The lake is fed by the Cowlitz River, which is a significant source of hydroelectric power for the area. The primary surface flow providers to the lake are the Cowlitz River and the Tilton River. The lake's water level fluctuates due to the snowpack in the surrounding mountains, which serves as a source of water for the region. The lake has been utilized for various recreational purposes, including fishing and boating, and plays a crucial role in supporting local agriculture. The reservoir is home to several fish species, including salmon and steelhead, and is a popular destination for anglers.
| Lake Or Reservoir Water Surface Elevation Above Ngvd 1929, Ft 24hr Change | None% |
| Percent of Normal | None% |
| Minimum |
843.73 ft
2021-11-14 |
| Maximum |
861.84 ft
2021-09-06 |
| Average | 861 ft |
Cowlitz River Near Kosmos
|
15600cfs |
Cowlitz River At Randle
|
11500cfs |
Cispus River Ab Yellowjacket Creek Near Randle
|
2640cfs |
Tilton River Ab Bear Canyon Creek Near Cinebar
|
3080cfs |
Mineral Creek Near Mineral
|
797cfs |
Nisqually River Near National
|
2160cfs |
| Location | Reservations | Toilets |
|---|---|---|
Taidnapam Park - Tacoma Power
|
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Iron Creek Campground
|
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Campground: Iron Creek
|
||
Obscurity Camp
|
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Panhandle Camp
|
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Shovel Camp
|
Goat Rocks Wilderness Bounday To Cowlitz Falls Ferc Project Boundary In Ne1/4 Of Nw1/4 Of Sec 4, T11N, R6E
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