OSMP Closures

Muddy trail closures

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Other Trail Closures and Advisories

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.

Flagstaff Summit Road closed to vehicles for winter
The summit road is closed to vehicles until May. Visitors may still access the area on foot.

Anemone Hill Trail weekday closures
The new Anemone Hill trail system is open to public use during evenings and weekends (also open Thurs. 11/25 & Fri. 11/26). During workdays between 5 a.m. and 5 p.m., Monday through Friday, Anemone Hill is closed as trail construction work continues on the lower/east approach section. The trail is anticipated to be fully open in early 2022, but the construction schedule is dependent on winter weather conditions.

Creek Closures to Limit Spread of Invasive Mudsnails Instituted
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. While the city implemented limited South Boulder Creek closures to help stem the human-caused spread of mudsnails in October, it is taking additional steps to prevent their spread into uninfested stretches of the stream by closing creek access at the South Mesa Trailhead and areas to the west. Learn more about the NZMS closures.

Cottontail Trail construction delay; Closure to remain in place
City of Boulder Open Space and Mountain Parks (OSMP) has completed trail improvements along the main section of the Cottontail Trail that is part of the Longmont-to-Boulder Regional (LoBo) Trail. That section of trail northeast of Boulder is ​currently open ​and will remain open – with the exception for short maintenance closures later this year.

However, construction along the section of Cottontail Trail between Lookout Road and the LoBo trail – east of the Gunbarrel Estates neighborhood – is delayed because the contractor that began trail work has told the city it is no longer able to continue construction activities. OSMP is working as expeditiously as possible to restart trail construction, which requires a contractor with specialized tools and equipment to construct engineered drainage crossings and site grading. ​This section of the Cottontail Trail will remain closed as the area is an active construction site that presents safety risks to visitors.

Because the city must ​equitably select a new contractor through a procurement process, which will require new bids from other vendors, OSMP cannot provide a specific date for when ​trail work will restart. OSMP recognizes this trail section's importance to community members, and the department appreciates their patience while we secure a contractor to complete trail construction.

Rock Island 1 in Boulder Canyon closed
Rock Island 1 is closed. The rock fractured and part fell onto the Boulder Canyon Creek path. Sections of the remaining rock have been evaluated as unstable so it is closed until recommended bolting can be completed.

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.

The areas below are closed from Nov. 1 to July 31 for the protection of nesting and roosting bald eagles:

• 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.

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 South Boulder Road to Marshall Road

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.

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 Nov. 1.

Due to bear activity dogs must be leashed from 8-15 to 11-1 on the following trails:

• Portions of Gregory Canyon, Saddle Rock and Amphitheater Trails
• Skunk Canyon up to the Mesa Trail
• Upper part of Doudy Draw Trail

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.

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:

• Cosslet/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.)
• Superior Associates and Kelsall Properties (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.

All cliff-nesting raptor closures have been lifted for 2021.​​​​​​

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 cliff nesting raptors:

• Lefthand Canyon Palisades, at the intersection of Lefthand Canyon Drive and Olde Stage Road (Buckingham Picnic area remains open).
• Flagstaff Mountain, the north side of Flagstaff Mountain. The Boy Scout Trail remains open.
• May’s Point cliff, May’s Point Trail will remain open.
• 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.
• Skunk Canyon, including Ridges 2, 3 and 4, the Aechean Pronouncement, the Dreadnaught, the North Ridge and the entirety of Sacred Cliffs.
• The Back Porch and The Box.
• Der Freischutz.
• 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 Sphinx
• The Wings
• The Apostle.
• 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.

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.

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