Barrier Dam, also known as Mayfield Fish Barrier Dam, is a concrete structure located on the Cowlitz River in Toledo, Washington. Built in 1968, this dam serves the primary purpose of creating a fish and wildlife pond, with a normal storage capacity of 455 acre-feet and a maximum discharge of 68,350 cubic feet per second. The dam stands at a height of 16 feet and has a length of 718 feet, with a spillway width of 318 feet.

Managed by the Federal Energy Regulatory Commission, Barrier Dam has a low hazard potential and a moderate risk assessment rating. Despite not being state-regulated, the dam plays a crucial role in supporting the local ecosystem and wildlife populations. With its unique multi-arch design and rock foundation, Barrier Dam is a key component in the conservation efforts along the Cowlitz River, providing essential habitat for fish and wildlife in the region.

Water resource and climate enthusiasts will be fascinated by Barrier Dam's contribution to the environment, as well as its structural features and operational aspects. This dam not only serves as a barrier for fish migration but also as a reservoir for maintaining water levels and supporting the surrounding ecosystem. Its location within the Portland District and proximity to Lewis County makes Barrier Dam a significant landmark in the region, highlighting the intersection of water resource management and wildlife conservation efforts.