Columbia- Pacific Passage Habitat Restoration

The Columbia- Pacific Passage Habitat Restoration project is a multi-phase project involving three separate tributaries to the Columbia River Estuary. The 14-1380 project proposed the completion of phase II (Megler Creek) of the three phase strategy.

The overall fish passage improvement goal of the Columbia - Pacific Passage Habitat Restoration project at Megler Creek was achieved. The goal of this project was to reconnect the creek to the Lower Columbia River, thereby providing fish passage and maximizing estuarine habitat enhancement opportunities critical for the recovery of threatened and endangered Columbia River and tributary salmon species. This project removed a 48 inch perched culvert underneath a state highway (SR 401) that was acting as a fish passage barrier, and replaced it with a significantly larger (25 feet wide by 10 feet tall), 100% passable, stream simulation concrete box culvert. The new structure now provides full access to upstream spawning habitat adult Chinook salmon, chum salmon, coho salmon, steelhead, and cutthroat trout. The new structure also provides access to approximately 2 acres of rearing habitat for juvenile salmonids migrating through the estuary. Additionally, upstream of the new structure, tidal and fluvial habitats were expanded and enhanced, restoring the hydrologic and biological processes at the confluence of the creek and the estuary. This was done by removing 5,300 cubic yards of impounded sediment to restore the natural gradient of Megler Creek. Prior to the completion of this restoration project sediment transport processes had previously been cut off due to the presence of SR 401, and the undersized culvert. In addition to restoring the gradient of Megler Creek, the restoration project also installed a combination of engineered log jams, and cobble riffle structures were installed that are currently encouraging the formation of small pools which now provide suitable ingress/egress, and holding habitat for juvenile salmonids and other native fishes. These installed structures have created a naturally-variable yet stable longitudinal slope in Megler Creek reducing the scour potential and ensuring fish passage in upstream and downstream directions. The streambed cobbles and gravels were installed within the stream simulation box culvert as well as four separate locations upstream of the culvert to simulate existing creek substrate.

The restoration project required two types of amendments necessary to complete the project. The project required four separate time extensions primarily due to inclement weather. The combination of several severe storm/high wind events, and near record winter rainfall events, presented the project with extremely challenging work conditions and multiple periods of inactivity due to unsafe working conditions. In addition to the time extensions the project also required a minor cost amendment to address a project related safety issue within the roadway. A key element of the project involved removing a barrier to fish passage underneath SR 401, as a result, the project required the temporary removal and replacement of a section of roadway and its guardrail on SR 401. It became apparent towards the end of the project, once the roadway was being restored, that there was an unsafe section of guardrail within the project footprint that required additional length of rail as well as an updated crashworthy guardrail terminal. The guardrail conditions were a direct result of the project and required correction in order to provide a safe roadway for the general traveling public. After project completion the project restored habitat connectivity, fish passage, and improved both the infrastructure and safety for the traveling public along SR 401.

Restoration actions at Megler Creek consisted of removing the undersized culvert at the confluence of the creek, and replacing it with a 25 foot wide stream simulation concrete box culvert. The project corrected the previous fish passage barrier and improved access to 1+ miles of upstream spawning habitat, as well as improved the off-channel rearing habitat by enhancing tidal connection to approximately 2 acres of estuarine wetlands that had been disconnected due to short-circuited sediment transport causing sediment to impound several feet behind the roadway. The restoration project removed the impounded sediment and restored the natural gradient of the creek. The outcomes of the project include improved habitat connectivity; barrier elimination; improved and expanded side-channel habitats; improved nutrient exchange processes, increased availability of preferred habitat; and expanded macro-detritus based food web. The finished project is benefitting Chinook, chum, coho, as well as steelhead and cutthroat trout.