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Habitat Conservation Areas

Habitat Conservation Areas

Habitat Conservation Areas: Preserving our Wild Heritage

The City of Boulder Open Space and Mountain Parks (OSMP) department designated nine Habitat Conservation Areas (HCAs) as a way to protect areas that provide habitat to some of Boulder’s rare plants and animals. HCAs protect some trees and flowers so unusual that they are found nowhere else in Colorado! Other species in HCAs are listed as threatened under the Endangered Species Act. View a map showing the location of OSMP's management arreas pdf, including HCAs.

You can help preserve and protect these extraordinary areas by staying on trail, observing closure signs and regulations, and avoiding nighttime use from one hour after sunset to one hour before sunrise.

Southern Grasslands HCA

This HCA protects a 3,000 acre remnant of intact grassland and the plant and animal species that depend upon it. Visitors to the area may see wildlife such as badgers or burrowing owls. A restored section of Coal Creek cuts across the HCA. Bald eagles return each year to nest in the cottonwood trees along its banks and many ground-nesting birds breed here each spring, such as meadowlarks and grasshopper sparrows. To visit this HCA, walk the High Plains and Greenbelt Plateau trails.

With the opening of the High Plains Trail, OSMP was able to provide new opportunities for hikers, cyclists, and equestrians to enjoy and access this HCA while at the same time establishing protections for the grassland plants and animals that live there. Off trail travel in this HCA requires a special permit.

Western Mountain Parks HCA

Boulder’s climate was cool and moist 10,000 years ago during the last Ice Age. Thick deciduous forests covered the foothills. As the Ice Age came to an end, the climate became hot and dry. The moisture-loving forests were replaced by Ponderosa Pines and drought-tolerant shrubs except in a few cool canyons where Ice Age conditions—and plant communities—can be found to this day. Nowhere else in Colorado can you find Paper Birches (Long Canyon Trail) or the tiny White Adder’s Mouth orchid. Western Mountain Parks preserves areas unbroken by roads or trails, preserving habitat for animals like wild turkey, bobcat and black bear. Narrow tree-lined canyons attract nesting flammulated owls and Williamson’s sapsuckers. One way to enjoy this HCA is to hike the “Triple Peak Challenge,” a strenuous day hike that takes you across all three summits of the mountain backdrop on the Green Mountain West Ridge and Greenbear trails.

In 2008, six new properties were added to the Western Mountain Parks HCA, increasing its size by 200 acres along the western edge. In 2011, an additional 100 acres were acquired protecting significant habitat and allowing the completion of the Chapman Drive Trail – a multiuse connection between Flagstaff Mountain and Boulder Canyon. Like the Southern Grasslands HCA, OSMP requires visitors to stay on the trail in the Western Mountain Parks, unless they have obtained an off-trail permit.

Lower Boulder Creek HCA

Cottonwood trees line the bank of Boulder Creek as it flows across eastern Boulder County. Animals use the creek to move between farms and fields in the security of streamside thickets. Lower Boulder Creek’s abundant water provides habitat for many amphibian and reptile species including the only occurrence of the six-lined race runner lizard on OSMP. Several pools along the creek provide a refuge for fish, where they can restock the populations up and down the waterway. The area can be accessed on the East Boulder/White Rocks Trail. Visitors may see bald eagles, northern harriers, belted kingfishers, and Great blue herons, which nest in a protected rookery just east of the HCA.

In 2013, the city enlarged the Lower Boulder Creek HCA by 655 acres with the acquisition of the Ertl Ranch. Because of special characteristics of the Lower Boulder Creek ecological systems, including protection of nesting bald eagles, off trail travel is not allowed in this HCA. A limited number of guided hikes are conducted by Open Space staff in late summer and early fall after eagles have fledged. More information about guided hikes in this HCA and elsewhere can be found on the Natural Selections webpage.

Eldorado Mountain HCA

The diverse terrain of Eldorado Mountain provides habitat for plants and animals. Here you’ll find shady old growth pine forests, dry meadows, cool canyons and dense shrub thickets. Few trails or roads bisect this area, making it available for animals such as Northern goshawks, mountain lions, prebles meadow jumping mice and rare butterflies such as Shryver’s Elfin.

The Eldorado Mountain/Doudy Draw TSA Plan was completed in 2006, identifying two trails to provide access to the Eldorado Mountain HCA. When the Goshawk Ridge Trail was opened, OSMP also established on-trail requirements for this HCA. As with the Western Mountain Parks and Southern Grasslands HCAs, travel off the trail is only allowed for visitors with permits.  

Jewel Mountain HCA

The grassy flats beneath Jewel Mountain are relatively undamaged because its stony soil was too difficult for settlers to plow. This unusual “xeric” (dry land) tall grass prairie is home to a number of rare butterflies such as the Arogos and Crossline Skippers. Jewel Mountain is home to elk herds that migrate between the mountains and eastern plains. Southern Arapaho cultural sites also make this an important area. Jewel Mountain HCA is not open to public access. 

North Foothills HCA

The geology underlying the land supports and defines the living communities above it. This is especially true in the North Foothills HCA, where outcroppings of Smoky Hills shale score the landscape. The shale creates soils rich in selenium, which support unusual plants. The Colorado Natural Heritage Program lists many of this HCA’s plant communities as “sensitive” at the state-wide level. Look for the yellow-flowered Bell’s Twinpod in spring which is unique in the world to the selenium-rich shale barrens along the Front Range. The rare birdsfoot violet also crops up here and there. Rattlesnakes from the surrounding areas congregate here in winter, hibernating within rocky crevices. If you have sharp eyes, you may see Horned Lizards, commonly known as Horny Toads, sunning themselves on rocks.

Identified in the OSMP Visitor Master Plan in 2005, the North Foothills HCA was enlarged in 2013 when OSMP purchased Joder Arabian Ranch. Access and measures to protect the ecological values of the area are currently being developed in the North Trail Study Area Plan. The interim Joder and Hogback Ridge Trails provide on-trail access to this HCA.  

Tallgrass Prairie East HCA

When the Ice Age came to an end 10,000 years ago, Colorado’s lush stands of tallgrass prairie couldn’t take the heat, and were replaced by drought-tolerant grasses. But in isolated pockets around Boulder, tiny remnants or “relicts” of this ecosystem remain. This HCA preserves some of the most important stands of dryland (xeric) tallgrass prairie west of the Mississippi River. In fall, grasses take on delicate and subtle shades of ochre, tan, wine and purple. These pockets of habitat support rare plants like the Ute Ladies’ Tresses Orchid, which is protected under the Endangered Species Act and the American Ground Nut, known to grow in only six sites in Colorado (four of them on OSMP). Bobolinks, disappearing across much of their range, still nest here, as do common snipe and meadowlarks. Prairie dog colonies in this HCA attract hawks, eagles and American badgers.

This 1,600 acre HCA was identified in the Visitor Master Plan. No trails have been designated in this HCA. Many visitors enjoy the South Boulder Creek Trail, which runs along the edge of this HCA. A small but highly visible parcel on Davidson Mesa (near the overlook on US 36) was added to the HCA in 2006 to protect the scenic entry into Boulder from the southeast. 

Sombrero Marsh HCA

Sombrero Marsh may have been the only perennial body of open water in Boulder Valley at the time of settlement. Sombrero is an alkali marsh, rare in this part of the United States. It is shallow and periodically dries out, leaving mudflats that provide unique habitat for emergent vegetation and nesting wading birds. But it wasn’t always this way! It had been used as a garbage dump until 2000, when OSMP acquired the marsh. OSMP began restoring the marsh, first hauling out 55,000 cubic yards of trash, then replanting native alkali marsh vegetation. Several short trails and a board walk now skirt the eastern shore for use by the public, school groups and classes at Thorne Ecological Institute.

Identified in the Visitor Master Plan in 2005, Sombrero Marsh is a relatively small HCA (initially just 45 acres). A development on adjacent lands led to the dedication of another eight acres including about a quarter of the actual marsh along with surrounding uplands. Further planning for this HCA will take place during the East Trail Study Area process.

Cottonwood Grove HCA

Many species of songbirds nest among the foliage of the cottonwood trees that like Boulder Creek, including yellow warblers, northern orioles, blue grosbeaks, and American goldfinches. In the grassy meadows, rabbits search for food and watch out for red foxes and great horned owls. Because of the research value of this habitat, the Cottonwood Grove HCA is closed to visitors. An agreement with the University of Colorado has provided long-term research at Cottonwood Grove HCA.

The Visitor Master Plan and Off Trail Permits

One of the ways that HCAs protect ecological systems is by requiring visitors to stay on designated trails. Off-trail permits are required to travel away from the trail in the following HCAs:

  • Southern Grasslands
  • Western Mountain Parks
  • Eldorado Mountain 

Off-trail activities include hiking, bird watching, photography, climbing and running. Dog walking and bicycle riding are not allowed off-trail. Designated trails are always marked with signs that include a trail name. Dog walking and bicycle riding are not allowed on or off trail on Goshawk Ridge Trail in the Eldorado Mountain HCA, and equestrians may only travel on trail. Nighttime use (one hour after sunset to one hour before sunrise) in HCAs is discouraged.

Off-trail travel is not allowed in the Lower Boulder Creek HCA.  
No visitor access is allowed in the Jewel Mountain or Cottonwood Grove HCAs.

Off-trail access is currently allowed but discouraged for the following HCAs

  • North Foothills
  • Sombrero Marsh
  • Tallgrass Prairie East

No off trail permit is required for these areas.

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