Penn State’s Center for Dirt and Gravel Studies combats pollution from unpaved roads

Penn State's Center for Dirt and Gravel Studies combats pollution from unpaved roads

Some unpaved roads reveal nature’s simple engineering, like the path deer chose in a forest centuries ago. Native Americans used the deer paths to travel, and those trails widened over time for horses and buggies to become dirt roads.

Pennsylvania is home to approximately 23,000 miles of unpaved public roads, and there are likely thousands of miles more on private property and in the vast Allegheny National Forest. They’re more than just a quaint feature of rural America, too. School buses, mail and other delivery vehicles, first responders, and a growing number of gravel-loving cyclists and outdoor enthusiasts use them daily.

In places like Bradford County, which has the most miles of unpaved road in the state at just under 1,600, maintaining the dirt and gravel isn’t just about transportation and smoothing out a bumpy ride, though. It’s about water quality.

“With all those miles here, just about every dirt road in the county touches a waterway of some sort,” said Joe Quatrini, a dirt and gravel roads specialist with Bradford County’s conservation district.

Many dirt and gravel roads hug the banks of rivers and streams, two lines on a map following the path of least resistance like two synchronized snakes. On an ideal gravel road, rainfall disperses evenly across the surface, like a sheet of water, filtering through more land before it reaches a stream. Unmaintained or “orphaned” roads that no one’s taking care of often sink or become deeply rutted, forming small bogs. When it rains, those rutted roads can funnel water, collecting sediment, trash, and other pollutants like pesticides, oils, and fertilizer into an erosive torrent that rushes into a creek. That sheer volume of water can wash away stone and rock beds that fish and other aquatic life need to breed.

“The sediment is the main impact from a dirt road, and that’s what our program aims to eliminate,” said Justin Challenger of the State Conservation Commission. “That’s why we’re more of an environmental program than a traditional, PennDot type of road program.”

The state’s effort to address sediment runoff from unpaved roads was inspired by some frustrated trout fishermen and resulted in the opening of Penn State’s Center for Dirt and Gravel Studies in 2001. In the last two decades, Penn State’s unique program provided training and technical assistance for thousands of projects in nearly every Pennsylvania county. It has also advised a handful of other states, including Arkansas and Vermont, on how to develop their own. The center is the educational arm for Pennsylvania’s Dirt Gravel and Low Volume Roads Program, which provides the grant funding for the projects through the Conservation Commission in Harrisburg.

Pete Ryan, a dentist and avid trout fisherman from Coudersport, in rural Potter County, saw that process play out time and time again on his favorite streams when it rained. One late-spring afternoon, in 1990, he eyed an overcast sky over coffee, looking for divine intervention in the charcoal clouds rolling through the county. The sulphur and green drake mayflies were hatching all over northern Pennsylvania, and rainbow, brook, and brown trout would rise to eat them in the county’s cold, clear streams. Fishermen would try to fool a few into biting fuzzy hooks instead.

But Ryan hoped rain would ruin the fishing that day in “God’s Country,” so he could prove a point. And the heavens opened up.

“It was perfect,” Ryan recalled.

Ryan and another member of the God’s Country chapter of Trout Unlimited had invited a state biologist, a Penn State professor, and a fellow fly fisherman to Potter County to show them how those timeworn, unmaintained dirt and gravel roads affected water quality in those world-class trout streams. Rain, like the kind they saw that day, flowed quickly into Big Moores Run, clouding up the water in the short term but also introducing pollutants and washing away rock.

“It was like pouring milk into coffee,” Ryan said of the runoff.

As a direct result from that rainy day in Potter County, a state task force on dirt and gravel roads was formed in 1993. For the next five years, volunteers from Trout Unlimited, a national nonprofit that advocates for clean waterways and fisheries, traveled the state, identifying approximately 900 sites where sediment from unpaved roads was disrupting waterways. The number of potential sites grew to 12,000.

State funding for maintenance was approved in 1997 and Penn State’s center opened in 2001, focusing on educating and training county conservation districts. From 1997 to 2013, the dirt and gravel maintenance program received $4 million in funding per year. That number jumped, in 2014, to $28 million with a minimum of $8 million per year dedicated to low-volume roads that see fewer than 500 cars per day.

“In most areas, the number of gravel roads are likely decreasing, but in some rural areas, when townships realize they can’t afford to maintain paved roads, they’ll actually rip it back up,” said Steve Bloser, director of the Penn State Center

While students can’t major in “dirt and gravel roads” at Penn State, Bloser said, the center developed a “Rural Road Ecology” class primarily for forestry or engineering students.

On a recent winter day in Potter County, Pete Ryan and Andrew Mickey, the county’s dirt and gravel roads technician, took a drive out to Big Moores Run to see where the state’s gravel and dirt road maintenance program began. Big Moores Run Road was covered in snow. Trout, Ryan said, are like the canaries in the coal mine — but for watersheds. They demand cold, clean water, free of pollutants. In Potter County, the trout population is thriving, because the roads are maintained.

“We don’t have development or industry,” Mickey said. “We just have a huge dirt-road network.”

When Mickey stopped his truck by a stream crossing, brook trout darted off in the clear water.

Fishermen aren’t the only group that care about dirt and gravel roads. All over the state, cyclists and runners are looking to gravel as a softer and safer substitute for traditional roads. Dave Pryor runs unPaved Pennsylvania, which promotes gravel and dirt bicycle riding and racing. He sees the state’s abundance of gravel and dirt roads not only as a playground but as an economic driver. The 2021 unPAved race of the Susquehanna River Valley Pryor hosted saw more than 800 participants from all over the country converging on Lewisburg, Union County, for a weekend.

“There were a lot of events in the Midwest, and I figured we need to do this in Pennsylvania,” Pryor said. “The public lands we have in Pennsylvania are gems. We have miles and miles of quiet, gravel roads. We have some of the best in the country.”

On a fall day in Lehigh County last year, Pryor was out scouting random gravel roads near Emmaus. Like many, this one ran beside a creek. People lived along it, and every few minutes or so, a car would pass. Farther down the road, a metal sign credited the county’s conservation district and the Penn State center for a reconstructed stream crossing.

“Better roads, cleaner streams,” the sign read.

Pryor said he’s raced in other states where rainfall all but shuts riding down.

“Or it gets so muddy you have to walk your bike,” he said. “Here, it could rain for a week, and you’d get wet, but you’d still be able to ride.”

The bicycle industry now makes gravel-specific bikes that can cost as much as $6,000. There are magazines dedicated to dirt and gravel riding, and Pryor’s wife, Selene Yeager, wrote a book about the phenomenon called Gravel!

“Gravel riding is the hottest thing in bikes right now,” Outside Magazine wrote in 2020.

The Penn State center said Philadelphia is the only county in the state without a conservation district, and the city isn’t on its list of counties with unpaved mileage. The city does have dirt and gravel roads in parks, however, including Forbidden Drive, a gravel road that mostly serves as a popular recreation area for cyclists, runners, and hikers. It runs just feet from Wissahickon Creek.

In 2020, Pennsylvania’s dirt, gravel, and low-volume road maintenance program helped build or replace more than 1,200 culverts to break up surface water flow. It builds buffers and bridges and fills in roads that have become “entrenched,” or sunken, after decades of use. The program used 395,000 tons of fill to build them back up in 2020.

“Some of these roads can be 100 years old,” Bloser said.

While COVID-19 affected the number of projects able to be done in recent years, Bloser expects work to ramp up again in the coming years.

On very rare occasions, when homeowners and other stakeholders are gone and public use has dwindled, some counties will give their unpaved roads back to nature. That’s often the case with old logging roads. Bloser said the goal, in those rare instances, is to “obliterate” the road and fill it in.

Grasses grow again, then trees, and roads slowly become hiking trails and deer paths again.