Deer Creek Floodplain Enhancement

Two images comparing Deer Creek pre and post work. Shows changes in the stream bed since project
Photo Story: Deer Creek Restoration

Deer Creek is the largest tributary to the McKenzie River within the Headwaters McKenzie River Watershed and is located east of Eugene, Oregon. The subwatershed of Deer Creek is approximately 14,800 acres in size and ownership is almost entirely federal lands. Deer Creek runs approximately 8.2 miles from its headwaters to its confluence with the McKenzie River at river mile 79.Large trees placed into Deer Creek to improve fish habitat

Past land management practices had impaired watershed processes and contributed to poor habitat conditions in lower Deer Creek. Riparian logging and the subsequent flood of 1964 caused complete scour of the floodplain, clearing all vegetation. Following the flood, and for years to come, the USFS salvaged most of the remaining instream wood. Several berms were later built to straighten the channel and prevent channel migration.

These land management practices severely reduced channel and floodplain roughness and increased the transport capacity of the channel, meaning that much of the wood, gravel, and fine sediment in Deer Creek were frequently transported out of this high energy system. As a result, the recovery of large wood had been slow (less than 20 pieces of large wood per mile), the substrate was too large for spawning, and most of the flow was confined to an incised, single-thread channel that was no longer connected to its floodplain. These conditions were severely impacting habitat for native species, including ESA-threatened Spring Chinook Salmon and Bull Trout. Major limiting factors for all fish species include: lack of spawning gravel, lack of off-channel habitat and high flow refuge, lack of deep pools, lack of cover, lack of large wood, and high summer stream temperatures.

An excavator and worker place logs into the stream bedThe project was designed to restore floodplain connectivity and channel complexity and enhance habitat for native fish and wildlife in the lower 1.6 miles and 42 acres of floodplain. In 2016, 200 whole trees (24-36”dbh) were harvested from upland units, broken in half, and placed in Deer Creek with an excavator. Berm material was pushed into the mainstem channel with a dozer to raise the elevation of the incised channel. And five large (38-63”dbh) streamside trees were pulled over into the floodplain to act as key pieces. In 2017, an additional 20 trees will be pulled over to complete the project.

Because an aggressive restoration approach was taken, results and benefits were immediate. Ecological function and habitat condition have already been vastly improved. Here are some examples:

  • A bankfull storm event in October 2016 reactivated the entire floodplain at low velocities and deposited abundant spawning-sized gravel. Instead of a single-thread channel, there are now multiple channels and slow off-channel habitat. Deep pools have already formed and fresh beaver cuttings have been observed.
  • A redd (a spawning nest built by female salmon) in the gravel of streams and wild female spring Chinook salmon were observed in October of 2017. Until this point, no spawning has been seen in Deer Creek since 1993.A redd is a nest made of gravel where female salmon deposit their eggs

BLOG: Will flooding bring fish back to Deer Creek?





https://www.fs.usda.gov/detail/willamette/landmanagement/resourcemanagement/?cid=fseprd530554