Just as highways need repair and occasional rebuilding, bike trails can also require some high-cost maintenance. That's on the minds of Three Rivers Park District planners, who maintain 15 regional trails with about 120 miles used by speedy commuters, casual bikers, daily walkers and strolling families.

Another 80 miles of trails are on the drawing board over the next decade.

"The regional trail system is going to eat us alive over the next 20 years" in terms of costs, Three Rivers Board Chair Larry Blackstad said recently. Commissioner Joan Peters called it "a monster waiting to happen."

The bigger the system, the more expensive it will be to keep up, said Three Rivers associate superintendent Boe Carlson. "At some point 20 or 25 years down the road, we're going to have to rehab all these trails, we're going to have to maintain them, we're going to have to deal with the issues as that infrastructure ages," he said.

Commissioners voted earlier this month to have Carlson study the possibilities for "an ongoing, secure and stable funding source" for the popular trail system. Officials said it has grown rapidly for both recreation and commuting, receiving an estimated 3.5 million visits in 2011.

One factor driving the concern is declining federal funds for trails.

The Three Rivers trail system received upwards of $10 million in federal transportation funds during the past decade, Carlson said, often with the support of former Minnesota Rep. James Oberstar, then chair of the House Transportation Committee and a well-known champion of bicycle trails and transit projects.

Oberstar lost a re-election bid in 2010, and changes in both committee leadership and policy have meant that trails now have a lower priority, Carlson said.

Money now goes to roads

"A lot of those dollars are now going directly into the roadway system," he said.

Three Rivers will prepare a position paper about alternatives for funding trails, Carlson said, including some possible new sources:

• User fees or some type of trail passes for certain corridors;

• Sales taxes on certain items that could be dedicated to trails;

• Initiatives at the Legislature that would earmark some transportation dollars for trails;

• Establishing a regional trail authority, perhaps with a broader metro base of funding.

System could triple in size

The Three Rivers trail system is part of a much larger network in the seven-county metro area that includes 308 miles of regional trails, according to Arnie Stefferud, a trails planning analyst for the Metropolitan Council. That system could more than triple to about 1,000 miles by 2030, he said, depending on demand and funding.

The council distributes bonding money for park capital improvements, Stefferud said, and also channels funds from the Parks and Trails Fund, approved by voters in 2008 under the Clean Water, Land and Legacy Amendment.

"There will always be a limit to the resources," Stefferud said. "The issue is the rate at which the park agencies want to develop the parks and trails in their jurisdiction."

In addition to Three Rivers, those trails are operated by Anoka, Carver, Dakota, Ramsey, Scott and Washington counties, and Bloomington, Minneapolis and St. Paul parks and recreation.

Tom Meersman • 612-673-7388