Spring Hill Farm Restoration and Enhancement Design

Project Description

In 2015, Metro, the Portland area’s regional government, purchased 247 acres of farmland adjacent to the Tualatin River, near a wildlife refuge and upstream from a water treatment plant. Recognizing that the purchase presented an opportunity to protect more than a mile of the Tualatin River and 1,250 feet of Harris Creek, Metro partnered with Clean Water Services (CWS), the region’s water resources management utility, on an effort to enhance the site’s riparian and in-water wildlife habitat. To undertake the assessment and design work, CWS turned to Biohabitats.

Biohabitats began by reviewing existing data, conducting a site assessment, and performing a hydrologic and hydraulic analysis of the site and inlet tributaries. Biohabitats and CWS crafted a 60% design that enhanced floodplain connectivity, removed man-made water control structures that limited ecological function, and improved and diversified instream and riparian habitat by restoring the tributary, daylighting a portion of a tributary that is currently piped, removing invasive species and floodplain berms, and installing habitat structures. Including agricultural set asides accommodated the community’s desire to maintain active agricultural use on some portions of the property. In keeping with Oregon’s Removal-Fill laws, Biohabitats developed ordinary high water (OHW) and wetland area designations. These determined cut-fill quantities below and above OHW. After facilitating review of the permit-ready designs by stakeholders and regulators, final, construction-ready plans were prepared.