Definition
Lake Merwin is a man‑made reservoir located on the Lewis River in the U.S. state of Washington. The lake was formed by the construction of Merwin Dam and serves purposes that include hydroelectric power generation, flood control, and recreation.
Overview
The reservoir lies primarily within Clark County, extending into the northwestern part of Cowlitz County. Merwin Dam, an earth‑fill structure owned and operated by PacifiCorp, impounds the Lewis River to create the lake. The dam was originally constructed between 1924 and 1926 and was subsequently rebuilt and modernized in the early 2000s to improve safety and operational efficiency. Lake Merwin is a popular local destination for boating, fishing, and other water‑based activities, and it supports a range of fish species such as rainbow trout, steelhead, and bass.
Etymology / Origin
The name “Lake Merwin” derives from Merwin Dam, which in turn was named after an early regional figure or a corporate designation associated with the dam’s original developers. Precise details of the naming origin are not well documented in publicly available historical records.
Characteristics
| Attribute | Details |
|---|---|
| Type | Reservoir (impounded by Merwin Dam) |
| Primary inflow / outflow | Lewis River |
| Surface area | Approximately 2,000–2,500 acres (about 8–10 km²). Sources vary; exact figure not confirmed. |
| Maximum depth | Roughly 80–90 feet (24–27 m). Accurate measurement is not confirmed. |
| Storage capacity | About 115,000 acre‑feet (≈ 140 hm³) according to PacifiCorp documentation; precise capacity may fluctuate with operational management. |
| Length | Roughly 5 miles (≈ 8 km) along the river valley. |
| Surrounding geography | Situated within the Cascade foothills; the shoreline is bordered by mixed coniferous forest and residential developments. |
| Recreational use | Boating, fishing, kayaking, and limited shoreline camping; a state‑managed boat launch provides public access. |
| Ecology | Supports cold‑water fish populations; the surrounding forest provides habitat for typical Pacific Northwest wildlife, including deer, black bear, and numerous bird species. |
| Management | Operated by PacifiCorp for hydroelectric generation; water levels are regulated in coordination with the U.S. Army Corps of Engineers for downstream flood control. |
Related Topics
- Merwin Dam – the earthen dam that creates Lake Merwin; a hydroelectric facility with a capacity of about 140 MW.
- Lewis River – the primary river feeding and draining the reservoir, a tributary of the Columbia River.
- Hydroelectric power in Washington – the state’s extensive network of dams and reservoirs used for electricity production.
- Clark County, Washington – the county encompassing the majority of the lake’s shoreline.
- Cowlitz County, Washington – the adjacent county that includes a portion of the reservoir’s northern extent.
- Recreational fishing in Washington – the broader context of sportfishing opportunities within the state’s many lakes and rivers.