TWIN FALLS (AP) - Mountain bikers have been on tenterhooks waiting for a decision from the U.S. Bureau of Land Management to authorize the Indian Springs trails south of Kimberly. But they're preparing for what may come.

The Southern Idaho Mountain Biking Association will hold a trail building and maintenance workshop at Auger Falls with the International Mountain Bicycling Association.

"It's about teaching people the proper way of building multi-use trails," said Nathan Fuller, SIMBA president.

The workshop will began Friday with a "Better Living Through Trails" presentation at Rock Creek Fire Department (242 U.S. 30, Kimberly).

Today, the Subaru/IMBA Trail Care Crew will hold an all-day Trail Building School. It starts at 9 a.m. with classroom work at the Twin Falls Area Parks and Recreation office (136 Maxwell St., Twin Falls), followed by hands-on training from 1 to 5 p.m. near Auger Falls.

The Trail Care Crew is a grassroots educational program which has acted as a mobile authority on sustainable trail-building practices since 1997.

"They literally drive around North America in a specially outfitted Subaru," said Mark Eller, IMBA communication director.

But they don't just drive around. The two-person trail crew leads trail work sessions - meeting with land managers and working with IMBA affiliates and the communities they serve to improve trail use opportunities.

"There's things you can do the right way and things that don't work so well," Fuller said of trail work.

The hands-on training will include basic sustainable trail design, Eller said. "It's designed for land managers and volunteers to pick up a bunch of practical information about trail-building."

That information will include the use of trail building tools such as pin flags, hand tools and clineometers. The latter is used to measure the angles of slopes and is a critical tool in building sustainable trails, Eller said. Erosion is a problem in steep areas and on long, straight trails.

"The whole idea really comes down to keeping water off the trails," he said.

The 1,000-year flood wreaked havoc on Colorado's Front Range last year is a good example of the importance of sustainable design. All the trails built to IMBA's guidelines in the area weathered the storm, Eller said. Most of the older, legacy trails were destroyed.

The IMBA Trail Care workshop comes at a perfect time for trail users in the Magic Valley. The 100-year storm which pummeled the area in August dumped 2.74 inches of rain on Twin Falls in 24 hours. The immediate impact of the storm was obvious in the city, but it also caused extensive damage to some of the Indian Springs trails south of Kimberly.

"For the most part, they held up," said Mike Goudy, owner of Spoke and Wheel Bike Shop. "There are sections that are completely gone."

Goudy, who rode the trails last week, said the heavy rain caused erosion, exposing problems with how the trails were built. Most are cow trails that bikers began riding in the 1980s.

"If it's not laid out right, it's not gonna be built right," he said.

The BLM began working with SIMBA more than two years ago to authorize the 40 miles of user-made trails in the area and to develop others. Authorization would allow for legal development and maintenance of the trails. Riding them is legal; maintaining them currently is not.

The authorization process hangs on the fact that the entire area is priority sage grouse habitat. Federal officials said the bird warranted endangered status in 2010, but it was not listed under the Endangered Species Act because other species took priority. A federal judge then ordered the U.S. Fish and Wildlife Service to make a final decision on the listing by 2015.

In the meantime, the BLM and U.S. Forest Service have been amending land-use management plans to keep the bird from being listed as endangered. The final statement and subsequent land-use plan amendment is expected to be released this fall.

"Nothing has changed other than the storm," Mike Courtney, the BLM's acting Twin Falls district manager, said Wednesday of the plan.

One thing has changed: The BLM authorized "minor maintenance within the trail track" on seven of the existing trails in the Indian Springs area, said Jim Tharp, acting field manager of the BLM's Burley office.

The decision to allow for trail stabilization came when Fuller sent Tharp photographs of the washed-out trails.

"We don't want them to get worse," Tharp said.

Fuller requested permission to reroute some heavily damaged trails, but Tharp said the work cannot be authorized without the amended land-use plan in place.

This month's workshop is free to attend. You must attend the morning classroom session to participate in the field project. IMBA suggests wearing pants, closed-toe shoes, a hat and gloves for the trail project. Participants should also bring water.

For information on the trail workshop, contact Nathan Fuller at [email protected].