Paul Polak has taken a walk every day for 15 years. When he imagines moving to a warmer climate, one thing stops him: “I enjoy the trails,” he said. “That’s why we haven’t moved.”

Rice Creek North Regional Trail, with its quiet fields and towering woods, is a favorite. But the paved route shows signs of wear and tear — cracks every few yards, sometimes so deep they split the path in two.

Growing demand for trails, by both nature lovers and commuters, has driven a building boom in Minnesota for more than two decades. Metro area counties and the state have added about 135 miles of paved trails in the past five years, rapidly expanding a network that crisscrosses the state and draws visitors year-round.

But as trails start to show their age, maintenance costs are mounting and officials are questioning whether enough planning and money has gone into preserving and connecting the sometimes disparate pathways. For state trails alone, maintenance is expected to cost $320 million over the next decade — and legislative funding is routinely falling short of what is needed, according to trail advocates. Counties that rode the building boom starting in the late 1980s are now facing trails that are showing their age. Anoka County plans to spend about $650,000 to rebuild and resurface trails over the next five years — $250,000 more than what it spent the previous five years.

“There are all these miles and miles of trails that have been authorized and there is concern. What are we going to do to maintain them over time?” said Erika Rivers, parks and trails director at the Minnesota Department of Natural Resources. “It is a real issue and we have to grapple with it.”

Insufficient, complex funds

Because trails often cross city and county boundaries, dividing maintenance responsibility and funding for repairs is complicated. It varies depending on the type of trail and what kind of maintenance is needed, and budget decisions can have implications for the future of parks as well.

Paved trails typically have a life span of 20 years before cracks, erosion and potholes require them to be completely rebuilt.

Trail-goers may notice those signs of aging, but other everyday costs, from removing fallen trees to repairing signs and bathrooms, aren’t always visible to users, Rivers said.

“There’s a list that goes on and on,” she said. “There’s an ongoing annual maintenance for every mile of trail … and that’s where I don’t think we have kept up with funding.”

Last year, state funding fell nearly $4 million short of what was needed, Rivers said.

As trail costs grow, some are worried about the impact on parks, which often rely on the same funding sources.

At a recent Dakota County meeting, residents railed against the addition of a paved trail through Lebanon Hills Regional Park, saying trail maintenance costs seem unsustainable.

“There’s so much at the park that needs to be rejuvenated, cared for and maintained,” said Anne Koutnik, of Eagan.

Dakota County plans to spend $32.3 million developing greenway trails over the next five years, but just $2.1 million on all parks and trails maintenance.

When it comes to regional trails, the responsibility and cost of maintenance often falls jointly on counties and cities.

Cities tend to handle routine maintenance, like snowplowing. If a trail needs to be repaved, that’s up to the county.

The Metropolitan Council gives trail maintenance money to 10 regional park agencies, drawing from different pools to pay for operations and longer-term rebuilding.

“The bottom line is, each implementing agency that we work with gets a certain percentage of the funds based on the formula,” said Jan Youngquist, the Met Council’s manager of regional parks and natural resources. “So they’re guaranteed a certain slice of the pie, if you will.”

Once the individual agencies get the money, it’s up to them to decide how to use it.

State and local agencies are shifting focus to preventive maintenance, said Thomas Wood, a research project supervisor at the Minnesota Department of Transportation.

“The idea is to spend a penny to extend the life and save dollars,” he said.

Demand for trails — particularly those that serve commuters — is still on the rise, despite decades of building.

From 2010 to 2013, visits to metro area regional trails grew by 2.7 million, according to the Met Council.

“Part of that, frankly, is that we’re adding more trails every year. When you add trails you’re going to have new users and more use and the numbers are going to go up,” said John VonDeLinde, Anoka County’s parks and recreation director. “One leads to the next.”

But gaps in the system remain obvious.

Scott County is just beginning to build a regional trail system and hammer out a maintenance plan to go with it. Until recently, there wasn’t a comprehensive plan for creating a countywide trail network, said Mark Themig, Scott County’s general manager for parks and trails.

One of the county’s biggest tasks will be piecing together the disparate trails it does have in place.

Jean Routh has struggled to find routes for biking near her home in Savage. “I hate to have to throw my bike in my car and drive to someplace in order to go bike riding,” she said. “The frustrating part is when I would rather just bike right from home, but there’s just not always good routes to get there.”

Even where trails are connected, best practices for maintaining them are still being developed.

Washington County is creating a new maintenance system that will track trail pavement conditions in the same way as road conditions.

The county is starting to realize that trails have different maintenance needs than roads, in part because of the way they’re used.

“From a standpoint of roller-bladers, you know, they notice smaller imperfections in the trail, whereas someone in a car probably isn’t going to notice a small imperfection or deterioration on a roadway as much,” said Cory Slagle, engineering and construction manager.

As trail use evolves, so should maintenance funding, said Jonathan Vlaming, associate superintendent of Three Rivers Park District.

Three Rivers’ long-term plan says a funding solution that counts regional trails as part of a transportation network “must be developed now, before the funding imbalance becomes so great that new regional trails are no longer financially feasible.”

A solution has not yet been developed, Vlaming said. Meanwhile, the agency is building two new trails that will cover more than 20 miles.