Mill Creek Stream Restoration 2013

This project improved connectivity of the Mill Creek stream channel to the floodplain by removing lateral berms and grading the floodplain. Instream habitat complexity and diversity were improved by reconfiguring the main channel, creating meanders, placing spawning substrate, creating pool habitat, placing large wood and boulder structures, and constructing side channels. Off channel habitat ponds and alcoves were excavated. Wetland habitat was improved by expanding existing wetland area through floodplain grading. Artificial wetlands were created by constructing perennial main channel alcoves and excavating ponds connected by constructed side channels. Riparian habitat was seeded and planted. Upland terraces were formed, seeded, and planted.

The CRITFC PCSRF funds ($103,663) were used for tree acquisition and delivery and to cover the cost for a contractor to harvest and deliver the whole trees. The rest of the funding ($116,337) was used to fund project construction. The BPA contributed funds were used to perform the other tasks required.

This project has been successful in achieving the desired outcomes related to habitat availability for focal salmonid species. Rearing and foraging habitats for juvenile spring Chinook salmon and summer steelhead was dramatically increased. Upon completion of the project, 0.49 miles of stream have been treated. The amount of suitable spawning habitat was increased with the addition of 1,640 yards of spawning gravels. Another example of project success is the total number of main channel pools created since project implementation. Prior to the project about 19 pools existed within the project area. Following implementation approximately 38 pools are now present. 10 acres were planted with riparian vegetation of native species.127 structures of unanchored individual logs, rocks and stumps with roots were placed in the channel. Overall, it is expected that this portion of Mill Creek will increase the survival and growth of focal salmonids inhabiting the project area. Below are two examples photos before and after project implementation.

Habitat restoration actions will benefit all life stages of focal salmonid species. The addition of deep pools, with cover, provides habitat for migrating adult salmonids and rearing juveniles. Juvenile salmonids now have a full suite of low-velocity, high-cover stream-margin habitats. These low-velocity areas are crucial for newly hatched salmonids until they become large enough to forage in pool and riffle habitats. Thermal (hyporheic exchange) and velocity refugia (high flow events) are now available through increased floodplain connection and the construction of off and side channel habitats. Over time, planted riparian vegetation will decrease solar exposure to stream channels, resulting in the maintenance of cool stream temperatures. Allochthonous inputs from riparian vegetation plantings will benefit the macroinvertebrate community by providing additional food sources. In general, the survival and growth of focal salmonids inhabiting the project reach of Mill Creek has the potential to increase. Furthermore, fluvial processes that create and maintain complex habitats used by all native fish have been restored at this site.

This project will increase riparian vegetation- Riparian vegetation creates velocity refugia during high flows, nutrient and forage inputs, and encourages habitat development in the form of undercut banks and woody debris recruitment through time. Therefore, 10 acres of locally sourced native riparian vegetation will be planted. Within those acres, 1.1 miles of side and main channel streambanks will receive the same treatment. old mill pond (referred to as Potter’s Pond) is located on the edge of the commercial forest in Mill Creek (rkm 9.7 – 12.1) and was historically used as log storage for the Warm Springs Forest Products Enterprise. In the 1940s, the pond was constructed using native floodplain material. Lateral berms were created bisecting the active floodplain in order to block stream flow. Fish passage was prematurely terminated by the construction and use of Potter’s Pond. In December 1980, high flows caused the earthen dams to fail resulting in erosion and excessive stream channel scour, essentially removing the pond (i.e., anthropogenic disturbance) but the nature of the disturbance was that of press disturbance, in which the system failed to recover and return to the nominal state. In the late 1980s, The Confederated Tribes of the Warms Spring Reservation on Oregon (CTWSRO) completed a project to increase habitat complexity. Natural recovery of the Potter’s Pond site has continued since the berms were breached in 1980; however, additional restoration actions are needed to address factors that continue to limit fish production.