Town of Rockford Reservoir & Riparian Improvements

The town of Rockford was in need of a funding source to replace its reservoir, as it was aging and inadequate for future growth. The town, with the aid of its local engineering consultant and the WRIA 56 Implementation Committee, submitted a grant application to the Department of Ecology (Ecology).

Ecology approved the application and provided grant funding of more than $800,000 to the small community. A condition of the grant was that Rockford also had to participate in a stream bank restoration and habitat enhancement project.

Rockford is looking to replace their existing 110,000-gallon reservoir with a 200,000-gallon reservoir; they also want to improve riparian habitat along several sections of Rock Creek in town. The riparian project will improve the riparian function, increase wildlife habitat, and stabilize stream bank erosion on a section of Rock Creek.

Charlie Peterson installs a riparian planting along Rock Creek.

In April 2008, the District installed a riparian planting of over 3,000 plants of varying sizes on the right bank, including an irrigation system. This portion of the project was successful and is being monitored.

The project treated approximately 350 feet of eroded stream bank, stemming from channel changes induced by cobble bar formation in the aftermath of the 1996-1997 high flows and flooding. The eroded bank and adjacent uplands had been grazed and no significant riparian plant community was established. The only established vegetation was a large Douglas hawthorn, some Serviceberry, Ponderosa pines and pasture grasses.

The treatment consisted of a biotechnical bank rehabilitation, using three fabric encased soil lifts on an armored toe. The first, second, and most of the third fabric encased soil lifts are faced with 18 and 12-inch diameter coir logs. Rooted Red osier dogwood, Douglas hawthorn and Coyote willow were placed in wet soil matrices between the lifts, as each was constructed. Native sedges found among the reed canary grass on the upstream portion of the site were salvaged and replanted at the face of the armored toe and first fabric encased lift.

The majority of the right bank bar, which had also been extensively grazed for a long period, was excavated for the left bank rehabilitation. Weeds, including tansy, dominate this area. The undisturbed right-bank-area was extensively planted with Ponderosa pine, Aspen, Woods’ rose, and Douglas hawthorn. A temporary irrigation system was constructed.

The eroding bank on Rock Creek.

Project objectives:

• Reconstructing the bank stratigraphy as closely as possible to original profile
• Establishing a native riparian vegetative community based on nearby reference reaches and determining a desired future condition (Ponderosa pine canopy, Douglas hawthorn/native bunch grasses/Red osier dogwood/tall manna grass/sedge/Coyote willow, in descending location on the face of the reestablished stream bank)
• Maintaining sediment carrying capacity
• Avoiding initiation of head cutting or disturbance of natural grade controls
• Maintaining or increasing channel length in the treated reach
• Minimizing impacts to water quality and aquatic life in Rock Creek during construction
• Immediate stability at completion of construction, in the event of a major high flow event

Filling soil behind the coir logs.

A balanced project using on-site materials:

The fill for the first two lifts was taken from the top, waterward portion of the cobble bar forming the right bank of the stream at the site. This material consisted of basalt cobble/rubble in a silty soil matrix, similar to the soil column on the eroding left bank.

Underneath the cobble layer is a clay lens. To replicate the native soil column as closely as possible, the final soil lift consists of silty loam excavated by sloping back the top of the stream bank. Removing material from the bar for the armored toe and soil lifts was designed so as not to shorten the channel during average mid-winter high flows.

Final seeding consisted of triticale on the regraded bar and newly constructed small bar on the left bank. The upper lifts were seeded with native bunch grasses, and the lower lift and armored toe will receive additional willow and sedge plantings.

The first soil lift.

Final soil lift.

The community has embraced the project and has raised over $11,000 as matching funds. Town officials hope to receive continued support from citizens, businesses, and private landowners along the creek.

Key Project Partners

• Town of Rockford
• Bruce Carmack
• Thomas, Dean & Hoskins, Inc.
• Washington State Department of Ecology
• Washington State Department of Fish and Wildlife
• WRIA 56