OSMP Closures

Muddy Trail Closures

• View muddy trail closures on the interactive map
• View muddy trail closures on the muddy trail closures page

Muddy Text Alerts

Text “OSMP” to 888-777 to sign up for text updates about muddy trail closures.

Other Trail Closures and Advisories

Flatirons Vista Trailhead one-day closure Aug. 6
The trailhead will be closed from 6 am - 4 pm for parking lot maintenance. Area trails will remain open, unless closed for muddy conditions.

East Boulder Teller Lake trail segment closed Aug. 11-15
The small segment of East Boulder Teller Lake Trail that goes east from the main trail to Teller Lake will be closed Monday - Friday, Aug. 11-15. The closure is needed for tree work using heavy equipment that will help with invasive species removal, fire mitigation, dam safety and water conveyance. The closure does not affect the main East Boulder Teller Farm trail between the north and south trailheads.

Mount Sanitas Trail Project
The city has begun a multi-year effort to improve trails and restore sensitive natural areas on Mount Sanitas. Work in 2025 will focus on summit approach repairs, bouldering area enhancements and closing redundant social trails. No full trail closures are expected, but intermittent delays may occur. Learn more about the Mount Sanitas Trail Project.

Chapman Drive Trailhead closure beginning March 3
The Chapman Trailhead and Bridge project is nearing completion. The underpass is now open, allowing visitors to pass between the Boulder Canyon Trail and Chapman Drive Trail. The trailhead is closed, but visitors can access the Chapman Drive Trail. View more on the Chapman Drive Trailhead Project page.

Sawhill Ponds Trailhead closure beginning March 3
The Sawhill Ponds Trailhead will be closed March 3 through the end of 2025, weather permitting, while OSMP completes major trailhead improvements. Visitors can access the Sawhill Ponds Trail during the trailhead closure through the Walden Ponds Wildlife Habitat trailhead and the Walden Ponds Trail to the north. Walden Ponds is managed by Boulder County Parks & Open Space and subject to county regulations. View more on the Sawhill Ponds Trailhead Project page.

Boulder Falls Trail closed effective November 12
The Boulder Falls area in Boulder Canyon is temporarily closed after a rockslide damaged the trail and infrastructure that keeps rocks and sediment from falling on the trail. There is no estimated timeline for when the area may reopen and more information will be provided once an assessment is completed. Climbers who access Dream Canyon through Boulder Falls should take alternate routes, such as Sugarloaf Road.

Marshall Mesa Trailhead closure
OSMP closed the Marshall Mesa Trailhead to support state coal mine mitigation work and conduct extensive trailhead improvements. The trailhead will likely be closed for one year. During the Marshall Mesa trailhead closure, visitors can access most of the Marshall Mesa trails. Bicyclists also will be able to complete the full "Dirty Bismark" loop. View maps and learn more on the project page.

Boulder Star Area closure
The City of Boulder reminds everyone to view the Boulder Star from afar as it remains closed. No designated trail currently leads to the Boulder Star. Learn more about viewing the Boulder Star from afar.

Creek closures to limit spread of invasive mudsnails
The City of Boulder has closed access to South Boulder Creek at the South Mesa Trailhead to prevent the spread of a highly invasive aquatic species, New Zealand Mudsnails (NZMS). The South Mesa Trailhead and the Mesa Trail will remain open. Learn more about the NZMS closures.

The area closures below do not close any designated hiking trails (climbing access trails may be affected). Please be sure to check for any leash restrictions if you are bringing a dog. Current area closures can be seen on the Wildlife Closures map.

Thank you for your cooperation in respecting the closures and providing the owls a quiet place to nest!

These areas are closed to protect nesting burrowing owls every year from March 15-Oct. 31:

• Cosslett/Knaus Property (north of the East Boulder Trail, south of Lookout Road and east of 75th St.)
• Jafay/Lynch Property (north of Lookout Road and east of 79th St.)
• Jenik/Cosslett property north of East Boulder - Gunbarrel Trail, south of Lookout Road. Vesper Trail remains open but dogs must be leashed.
• Gunbarrel Ranch property north and south of East Boulder - Gunbarrel Trail; the trail remains open.
• Superior Associates Property (north of Coalton Trail, trail remains open, south of Coal Creek)

This Parks and Recreation property will be closed through Oct. 31 if burrowing owls nest in the area:

• Boulder Reservoir (Dry Creek East): East of 51st/55th Streets, south of Dry Creek, west of the Boulder Reservoir water body and north of the private property on North 51st St.

All designated trails near these areas remain open to help visitors view wildlife species as they thrive in their native habitats.

The following area on OSMP is closed every year from March 15 to Sept. 10 to protect nesting osprey and Northern Harrier:

• Axelson: Part of the Axelson property near the Boulder Reservoir is closed from March 15 to Sept. 10 every year to protect nesting osprey.
• Boulder Valley Ranch: West of 51st/55th, west of Eagle Trail and west of the Boulder Valley Ranch pond.
• Sawhill Ponds: The southwest corner of the Sawhill Ponds property, located west of 75th St. between Valmont and Jay.

The following areas on Parks & Recreation land are closed every year from March 15 to Sept. 10 to protect nesting osprey, northern harrier and American bittern:

• Boulder Reservoir (Little Dry Creek East): East of 51st/55th Streets, south of private property on North 51st St., west of the Boulder Reservoir water body and north of the Boulder Reservoir Regional Park entrance.
• Boulder Reservoir (Little Dry Creek West): West of 51st/55th Streets, south of the Eagle Trailhead, east of Boulder Valley Ranch and north of private property on Valhalla Drive.
• Boulder Reservoir (Dry Creek East): East of 51st/55th Streets, south of Dry Creek, west of the Boulder Reservoir water body and north of the private property on North 51st St.
• Coot Lake: Within the wooden fence that surrounds the western portion of the Coot Lake area.

All designated trails near these areas remain open to help visitors view wildlife species as they thrive in their native habitats.

Female bats locate roosting sites in caves and rock crevices along the foothills, where the pups are raised in maternity colonies. The pups suffer high mortality rates even under normal conditions, so these closures help ensure they will remain undisturbed by humans during roosting season. Thank you for your cooperation!

Permanent closures:

The following areas are closed permanently to human use to reduce the chance of people introducing White-Nose Syndrome.

• Mallory Cave
• Harmon Cave
• Seal View Cave

Seasonal closures:

• Closed April 1 - Sept. 1: the east face of the climbing formation known as Der Zerkle is closed April 1 - Sept. 1 every year.
• Closed April 1 - Oct. 1: A buffer surrounding Mallory Cave is closed April 1 - Oct. 1 to protect Townsend’s Big-eared Bats. Instead of being part of the permanent Mallory Cave closure, the climbing routes on the east face of The Hand, the standard route on the Finger Flatiron, and all of Shark’s Fin are only closed from April 1 to Oct.1.

Closures

• Year-round - Dry Creek
• Year-round - Boulder Creek downstream of Valmont Road
• Year-Round - Areas west of the South Mesa Trailhead
• Temporary - South Boulder Creek from Marshall Road north to the East Boulder Community Center

Learn more about New Zealand Mudsnails and how you can help stop the spread.

The closures listed below are not currently in place. You may review the maps for reference, but these areas are not currently closed.

Grassland breeding birds have seen widespread and precipitous declines at a continental scale due to a variety of impacts. OSMP provides habitat for several species of grassland nesting birds including Grasshopper Sparrow, Western Meadowlark, Vesper Sparrow, Horned Lark, Lark Sparrow, and Savannah Sparrow. OSMP closes certain areas to help reduce human impacts that could disturb nesting birds.

These closures do not affect designated trails in the area which remain open throughout the closure period.

The following areas are closed May 1 - July 31 every year:

• Greenbelt Plateau: Both sides of the Greenbelt Plateau trail from the Community Ditch trail to the Greenbelt Plateau trailhead on Highway 128. Dogs must be on-leash on the Greenbelt Plateau trail;
• Doudy Draw: the area north of Community Ditch trail and west of Highway 93;
• Flatirons Vista: the area north of Flatirons Vista North trail and west of Highway 93 on top of the mesa; and
• Lower Big Bluestem: the area north of the South Boulder Creek West Trail, east of the Bluestem Connector and south of Shanahan Ridge (dogs are prohibited off-trail in this area year round).
• Hester, DeLuca and Campbell properties: located north of Nimbus Road and west of 39th Street.
• Jenik/Cosslett property: north of East Boulder - Gunbarrel Trail, south of Lookout Road. Vesper Trail remains open but dogs must be leashed.
• North Sky Trail: visitors must always remain on trail. Dogs are prohibited on the trail May 1 to July 31. Dogs are allowed on the trail Aug. 1 through April 30, but they must be leashed at all times.

Note: Dogs must be on-leash on Lower Big Bluestem year round due to West Trail Study Area Implementation.

Thanks to OSMP visitors and volunteers for supporting these closures and the cliff-nesting raptor program! The following areas (listed north to south) are closed from Feb. 1 - July 31 to protect falcons:

• Third Flatiron, including Queen Anne’s Head, W.C Fields Pinnacle, 1911 Gully and the Ghetto, the East Bench & West Bench, the East & West Ironing Boards, The Fin, Green Thumb and Jaws.
• Fern Canyon, north of the Fern Canyon Trail, including the Nebel Horn Ridge, East Ridge, the Goose and the Goose Eggs (the designated Fern Canyon hiking trail remains open).
• The Wings
• Shadow Canyon and the Matron: The Maiden remains open and accessible from the east; Shadow Canyon Trail remains open.
• The entire Mickey Mouse wall, including South Tower, North Tower, Central Tower, Ship's Prow, Wall of Shiva's Dance, The Gargoyle, the East Face and Cryptic Crags.

The following closures were lifted early:

• Lifted 5/29/25: The Sphinx
• Lifted 5/29/25: The Apostle

Please note: Golden Eagle closures now begin on Dec. 15.

The areas below are closed from Dec. 15 to July 31 for the protection of nesting Golden Eagles:

• Lefthand Canyon Palisades, at the intersection of Lefthand Canyon Drive and Olde Stage Road (Buckingham Picnic area remains open).

The following closures were lifted early:

• Lifted 5/15/25: Flagstaff Mountain, the north side of Flagstaff Mountain. The Boy Scout Trail remains open.
• Lifted 5/15/25: Skunk Canyon, including Ridges 2, 3 and 4, the Aechean Pronouncement, the Dreadnaught, Hippo Head, the North Ridge and the entirety of Sacred Cliffs.

The following areas are closed to protect nesting Bald Eagles from Nov. 1 - July 31:

• The Coal Creek area east of Highway 93 and south of Marshall Lake.
• The Kolb, Weiser and ERTL Properties east of 75th Street and north of Valmont Road.
• The entire Short and Milne Property, east of 61st street along Boulder Creek.
• The entire Boulder Valley Farm Property, east of 95th St, along Boulder Creek.

These areas are frequent foraging locations for bears. Leash restrictions protect dogs and their guardians when there is a high probability of encountering bears, and help avoid disturbing bears while they feed during the critical pre-hibernation period.

Seasonal Leash Restrictions are in place Aug. 15 to Dec. 1.

Due to bear activity dogs must be leashed from 8-15 to 12-1 on the following trails:

• Portions of Gregory Canyon, Saddle Rock, Amphitheater and Bluebell-Baird Trails
• Skunk Canyon up to the Mesa Trail
• Shadow Canyon South from the Mesa Trail up to the intersection with Shadow Canyon North
• The upper part of the Doudy Draw Trail above Springbrook Loop

Grassland Ground Nesting Bird restriction in place May 1 to July 31

The Greenbelt Plateau area is also affected by a seasonal leash restriction for grassland ground nesting birds from May 1 to July 31 every year: Both sides of the Greenbelt Plateau trail from the Community Ditch trail to the Greenbelt Plateau trailhead on Highway 128. Dogs must be on-leash on the Greenbelt Plateau trail, view map.

North Sky Trail: visitors must always remain on trail. Dogs are prohibited on the trail May 1 to July 31. Dogs are allowed on the trail Aug. 1 through April 30, but they must be leashed at all times.