Bohn Park Restoration

Bohn Park in Lyons, Colorado was devastated by the 2013 Flood. Record rainfall in the North St. Vrain Creek watershed caused the creek to overtop its banks and inundate Bohn Park. Almost all of the park’s amenities and infrastructure were damaged or completely destroyed.

Scott Shipley, Birch Ecology’s Co-Founder and the President of S2O Design – along with S2O’s engineers and planners – were part of the team selected to redesign and restore Bohn Park after the 2013 Flood.  As a part of this project, S2O was tasked with restoring the channel and floodplain of North St. Vrain Creek. The project included extensive modeling and the design of overflow channels to increase flood capacity and control future flood events.

A variety of creek stabilization and habitat structures were also designed and installed along the project reach. The creek reaches a maximum slope of 3% through the park.  In order to mediate the steep slope and respect the public’s desire to maintain the natural appearance of the park, S2O designed several boulder cross vane structures and created a series of pools and riffles. To provide habitat for aquatic species throughout the year, the restored stream was designed with deep pools, wetland areas, and proper structure and boulder placement.

On average, Bohn Park hosts 200 to 400 residents and visitors every weekend.  Therefore, balancing recreational creek access with protection of the riparian corridor was a critical issue for project design.  The design included strategically placed, hardened river access points that allow users to access the river for fishing and active creek recreation, while protecting the stream banks from erosion.  Fencing, signage, and elevated boardwalks were also used to protect riparian wetland habitats in the restoration area of North Saint Vrain Creek.  S2O completed the hydraulic modeling necessary to design and locate the boardwalk structures and pedestrian bridge.

Project highlights:

  • Extensive public outreach and public participation throughout the design process.
  • Design of three boulder cross vane structures and a series of defined pools and riffles.
  • Design and placement of habitat structures including: habitat boulders, rootwads, and a toe wood structure.
  • Detailed 2D hydraulic modeling of the park area that led to the design of two overflow channels to reduce the impact of future flood events.

Project Construction Cost: $1.2 million (Creek Portion) $4.1 million (Entire Park)

Key Staff: Scott Shipley, Nathan Werner, Christine Clark

Project Dates: May 2016- May 2017

 

Bohn Park Aerial Image 100712 pre flood
Aerial image of Bohn Park and the surrounding area prior to the flood on October 7, 2012. Source: Google Earth
Bohn Park Aerial Image 100613 post flood
Aerial image of the Bohn Park area following the flood on October 6, 2013. Source: Google Earth
Bohn Park Aerial Image 060917 pre flood
Aerial image of Bohn Park on June 9, 2017 with Phase I complete. Source: Google Earth
bohn 10 year
2D hydraulic model used to design overflow channels to mitigate future flood risk.
Bohn Park Root Wads
Installation of toe wood structures along the restored stream bank of North St. Vrain Creek.
Bohn Park North St Vrain Creek Restoration
View of the restored stream channel in January 2019.
Bohn Park Restoration Lyons Colorado 2
Bohn Park View Upstream from Bridge
View of the restored stream channel upstream from the 2nd Avenue Bridge.
Bohn Park View Downstream from Bridge
Restored stream channel downstream of the 2nd Avenue Bridge, January 2019.
Bohn Park Sign
Floodplain and creek access
Creek access point designed to protect against erosion.
Bohn Park Creek Access Ramp
ADA fishing access ramp.
Bohn Park Boardwalk and Bridge
Hydraulic modeling was used to confirm the design and location of the pedestrian boardwalk and bridge.
Bohn Park Boardwalk