BOULDER, Colo. (KDVR) — Hikers will have to navigate several closures to popular trails around Boulder this summer, as crews work on maintenance and repair projects.

Boulder Open Space and Mountain Parks will be closing one trailhead every Wednesday over the next two months for parking lot maintenance and repair work. A list of the trailhead closures is posted on the OSMP site.

Here are the trails where closures are expected during the summer:

First and Second flatirons

OSMP will be closing the trail from 8 a.m. to 4:30 p.m. Monday through Thursday in the summer to rebuild stone structures and restore native plant life along the trail. The closure starts at the base of the first flatiron and will be extended into the fall. Climbers may climb the first and hike down but may encounter delays.

Flatirons Loop

Closures will be in place from 8 a.m. to 4:30 p.m. starting in the summer and into fall Monday through Thursday. Crews will be installing stone steps, as more social trails have popped up along the main trail, to improve traction and discourage erosion.

Chautauqua Trail

Spot repairs will be needed in the fall, which will prompt “multiple 24-hour closures” of Boulder’s most popular trail.

Royal Arch Trail

Crews will continue to work on the Sentinal Pass, which leads to the Royal Arch formation. Helicopters dropped off material for work to rebuild steps along the pass. The trail will be closed as early as May 25, with full trail closures from 8 a.m. to 4:30 p.m. Monday through Thursday to continue the work from the summer into the fall. OSMP may close the trail on some Fridays during the same time window.

Bear Canyon Trail

These trail closures will be relatively minor and sporadic, according to OSMP. Hikers can anticipate 10-minute delays for work and the occasional closures that may span two days. Crews are rerouting a segment of the trail that is close to a stream and important wildlife habitat.

Mount Sanitas Trail

Hikers can anticipate trail maintenance in July, with temporary closures in the fall as helicopters move construction and trail material.

Mallory Cave

The trail will be closed for two days a week in October as crews repair switchback erosion and close down undesignated trails.

You can visit OSMP’s website for up-to-date details on trail closures this season.