Palouse Creek Habitat Complexity and Connectivity Project Development

The high-quality spawning habitat in the Palouse subbasin seeds the productive estuarine Haynes Inlet system of Coos Bay, promoting high potential coho productivity. The high-quality marshland once present in lower Palouse has been heavily altered to support agricultural pastures, resulting in stream channelization, undersized infrastructure, and removal of riparian vegetation. These activities negatively impacted water quality and instream habitat, resulting in the ODEQ 303(d) listing of Palouse Creek for bacteria, sediment, and stream temperatures.

This project is part of a larger watershed scale approach to improve function of the Palouse subbasin and will develop restoration designs to restore critical lowland rearing habitat and watershed function by improving stream complexity, floodplain connectivity, water quality, and flow conveyance across 1.3 stream miles and 45 acres in a manner that is compatible with the landowner’s management goals.

The Palouse subbasin is one of the highest productivity coho anchor habitat streams for its size on the Oregon Coast. The high quality spawning habitat in the upper watershed within the Elliott State Forest paired with the productive, diverse estuarine habitat in Haynes Inlet combine to release much of the potential coho population productivity in this subbasin. The tidal and head of tide reaches of Palouse provide degraged juvenile coho salmon rearing habitat due to the considerable alterations to the stream, leaving behind degraded channel complexity and limited access to off-channel rearing habitat. The proposed project reach is within the critical transition zone between the tidal zone and the forested uplands. The proposed restoration project will not only improve the quantity and quality of summer and winter rearing in this project reach but it will also improve the migratory connection between high quality upland habitat and the critical tidal rearing habitat.

This project is located in lowland habitats accessible to coho, chinook, steelhead, and cutthroat. This proposed technical assistance project will thoroughly evaluate current conditions and develop a holistic restoration project for this 45-acre parcel on Palouse Creek, containing 1.3 miles of critical rearing habitat. Breached levees and subsided have resulted in permanent standing water on the pasture, elevated stream temperature, and juvenile stranding and predation. This project seeks to address the prime limiting factors of critical rearing habitat, such as water quality and stream complexity, for coho smolt production in this subbasin. Channel reconfiguration will increase channel complexity by reestablishing sinuosity and other important habitat features such as complex pools, large wood, and hydrological connected freshwater wetland areas critical to lowland rearing habitat for juveniles, while providing the landowner with better drainage potential on their pasture.

Riparian fencing and planting will improve bank stability by reducing chronic sediment delivery and bacterial inputs, which is critical to improving water quality for salmon survival in a DEQ 303(d) listed stream (bacteria, stream temperature, sediment). Other long-term benefits from riparian plantings include toxin filtration, an increase in shade to cool stream temperatures and out compete noxious weeds, future recruitment of organic and woody debris for macroinvertebrates, which is an essential part of the juvenile salmonid diet.

Twelve culverts under Haynes Way Lane will also be evaluated as they directly connect to the proposed project area, most of which have not been surveyed since 2001. These crossings have the potential to restrict passage to nearly 2.5 miles of cool tributary habitat and become a source of catastrophic fine sediment input to the system. By evaluating these crossings, the risk of failure will decrease by developing upgrades to replace the high-risk crossings before they fail.

The high visibility of this project to the community can promote implementation of future projects that further enhance riparian buffers and stream complexity. This project is upstream of the future tide gate upgrade on Palouse Slough (OWEB #220-2024 and #221-2044), and while it is outside the direct tidal influence, it is in the critical head-of-tide transition zone between tidal-fresh and non-tidal fresh rearing habitat. The proposed actions of this project will significantly improve summer and winter rearing potential in this subbasin by restoring habitat between the spawning and estuarine habitats, which will capture and build upon the ecological benefits the new tide gate brings to this subbasin. By addressing these key limiting factors and linking migratory habitats promoting life history diversity and smolt fitness, juvenile survival and adult spawner abundance is expected to improve and fully release the ecological potential of the Palouse subbasin.