How the City’s Open Space and Mountain Park Team Has Revamped & Restored Boulder’s Flood-ravaged Trail System

In the fall of 2013, six days of torrential rainfall inundated Boulder County. This “1,000-year rain” led to what experts dubbed a “100-year flood,” a disaster that claimed four lives and caused widespread damage throughout the county. The flooding took an incredible toll on Boulder’s cherished open spaces, including substantial damage to the trail system and on agricultural infrastructure. In its initial post-flood assessment, Boulder’s Open Space and Mountain Parks (OSMP) team found that about one-third (over 40 miles) of the city’s trail system suffered extensive damage, with two-thirds (over 100 miles) suffering minor damage. In all, over 150 trails, trailheads, fence lines and other Open Space facilities were affected.

Fast forward five and a half years, add the efforts of over 1,486 volunteers working upwards of 8,000 hours, and OSMP has completed all of its major flood-rebuilding trail infrastructure projects. Thanks to its incredibly hard work, Boulder’s favorite trails have been restored to their former glory, and, in some cases, revamped beyond it. The Shadow Canyon South, Chapman Drive, NCAR-Bear Canyon and Chautauqua Meadow trails are prime examples of just how far OSMP has come since the devastation of 2013.

The NCAR-Bear Canyon and Mesa trails sustained extensive erosion damage, with ruts up to three feet deep cut into the soil. The waters also washed away a 36-inch culvert at Bear Creek Crossing, carving out a 5-foot deep hole in its place. OSMP repaired 1.75 miles of trail, resurfacing it with gravel and rebuilding a much larger culvert at the crossing. Four thousand one hundred feet of side ditches and ten culverts were added along the trail, intended to offset future flood damage by facilitating trail drainage and sustainability.

Located just off of the Mesa Trail, Shadow Canyon South also suffered erosion damage, which in this case ranged from a few inches to three full feet deep, with damage focused near the South Mesa Trailhead. OSMP, with the aid of five volunteer projects, filled in the ruts and hardened Shadow Canyon creek crossing with stone to curb future wash-outs. Also, they added over 5,100 feet of side ditches and 46 rolling dips. These new features will collect water from the road itself and surrounding slopes and divert it away from the road, all to improve drainage and reduce the probability of significant road damage in the future. Overall, 2.25 miles of trail were rebuilt, allowing for vehicle access for emergency response, OSMP administrative needs, and utility demands once again.

Beyond simply repairing damage done to the trail system, the OSMP team also improved upon select trails, implementing new features and further steeling them against future floods. In reconstructing the Chautauqua Meadow Trail, for example, the team went beyond simply fixing impaired drainage infrastructure and trail tread damage; they also made slight alignment changes, re-surfaced the trail tread, and restored and revegetated the surrounding land. In addition, they repaired culverts and side swales to facilitate drainage and minimize trail erosion. 

Chapman Drive, which stretches from its trailhead in Boulder Canyon to Realization Point, was subjected to erosion ruts that measured over four feet deep in some places, large landslides that took out large sections of the road and destabilized the surrounding slopes, and damage to the trailhead parking lot. OSMP worked diligently to rehabilitate the trail, repairing the damage to match the design originally crafted by the Civilian Conservation Corps (CCC), who were responsible for constructing the trail during the Great Depression. Additionally, they improved the drainage along the trail, replacing seven culverts and 3,700 feet of roadside ditch. As the OSMP department explains, their work on Chapman Drive not only improved visitor experience, but it also provided emergency vehicles an alternate access route to and from Flagstaff Mountain.

Faced with the rehabilitation of over 140 miles of the city’s trail system, Boulder’s OSMP team, aided by an army of passionate volunteers, worked tirelessly to breath life back into the city’s beloved trail system. Their efforts have paid off in spades; the staggering dedication of all those involved has left Boulder’s rolling landscape and winding trails even more stable, sustainable and resilient than ever before.

Back in Business: Seven trails that are rebuilt & ready for action

 

  • Royal Arch Trail

  • Gregory Canyon Road

  • Sanitas Valley Trail

  • Foothills South Trail

  • North and South Shanahan Trails

  • Lower Big Bluestem Trail

  • South Boulder Creek West & South Boulder Creek Trailhead

 

Lifestyle’s Top Three Favorite Trails: 

1. Walker Ranch Loop 

2. Enchanted Mesa Trail

3. Foothills Trail