The Upper Conner Creek Rehabilitation Project is set to mobilize Phase 1 construction early next week. The site is located approximately one river mile downstream from the Dutch Creek Bridge in Junction City. After mobilization, phase 1 rehab will focus primarily on the upstream portion of the area and consists of lowering the riparian floodplain, adding riffle enhancements, placing large wood to slow water and create habitat and planting of riparian vegetation. Crews began mobilizing equipment and staging areas Monday.
The largest feature of this portion is the R1 floodplain. This 5.7 acre broadly lowered surface and pilot channel on river left targets inundation at levels from 500 to 3,500 cfs. Given that this reach of the Trinity’s average winter flow is 771 cfs, this feature should remain wetted for much of the fall winter and spring, providing low velocity salmonid refugia and opportunity for riparian recruitment.
Supporting this floodplain/pilot channel feature, phase 1 will also see the construction of a riffle (IC-1 ) and the structured log jam (SLJ-1). The riffle (IC-1) is a 160ft long riffle that will raise the water surface elevation to encourage flows onto the new floodplain feature and has the added benefit of providing habitat for benthic macroinvertebrates, which are an important food source for salmonids. In between the main stem Trinity and the new pilot channel is a placed log jam (SLJ-1) which primary purpose is to provide temporary protection to the pilot channel, until riparian vegetation has an opportunity to establish. It is expected that this feature will eventually succumb to the forces of the river, but will provide low velocity salmonid refugia along the channel margins until then. Once revegetation commences this fall, the construction area will receive a compliment of cottonwoods, mixed willows, and a variety of sedges and rushes. The revegetation effort improves the aquatic habitat, helps prevent less desirable plants from taking hold, and generally speeds the healing of the river.
Junction City residents should expect to see increased traffic and activity along Red Hill Rd in the vicinity of the Smith Pit. Hours of operation on site are from 7am to 7pm, Monday thru Friday (with an allowance for Saturday if deemed necessary). Civil construction and revegetation of phase 1 should be completed by years end.
If you’d like to read more about the Upper Conner Creek Rehabilitation Project, please click here.