A Formal Assessment of Informal Trails

The slim ribbon of dirt I'd been following for a quarter mile skirted the edge of a bluff, ducked under a low oak and then dipped out of sight as it followed a precipitous line down the edge of a dredge tailing. I made my way down the steep slope of rocks that had been excavated from the American River's bed during the California Gold Rush, listening for periodic beeps from my GPS to ensure that I was indeed recording and updating my location as I traveled. At the base of the tailing, the trail wound its way around a fallen cottonwood and finally disappeared into blackberry bushes and poison oak. I turned around and clambered back up the rock pile, GPS and satellite photos in hand. At the top of the pile, I stopped to record the trail's width and level of degradation.

As an intern at the Sacramento County Department of Regional Parks, I've been tasked with developing and implementing a system of mapping and categorizing informal social trails in the American River Parkway. The mapping and classification will provide a concrete means of assessing recreational impacts on the parkway's natural resources, which include deer, quail, valley oaks and other native flora and fauna. The trail assessment will play a major role as part of the resource impact monitoring plan called for in the 2008 American River Parkway Plan. The plan's Resource Policy 3.4 requires that the monitoring plan, which has proved exceedingly difficult to develop, “clearly define criteria and standards to monitor, evaluate and protect the Parkway's resources.”

In a complex ecosystem, determining precisely when and how the environment is affected by recreational use is a difficult prospect. Formal equestrian, pedestrian and bicycle trails are already mapped, but parkway visitors who venture off these official trails to swim in the river or to cross a field leave behind trampled grass, compacted soil, and fragmented grasslands and riverbanks. They also leave behind a trail that is invisible. Mere human presence, however temporary, can alter the behavior and well-being of wildlife. And physical habitat fragmentation means there is less available space away from humans in which threatened species like the Swainson's Hawk can eat and live.

The assessment of informal trails will bolster the resource impact monitoring plan with data. But how can qualities like erosion, soil compaction and the loss of organic matter be incorporated in a classification system that is applicable to all trails on the parkway? What does the trail down the rocky dredge tailing at Sailor Bar have in common with a dirt trail through tall grass near the river? Scientists like Jeff Marion have spent their careers in pursuit of a scientific understanding of trail conditions. For the past few weeks, I have been combing through articles written by scientists like Marion in order to gain a thorough enough understanding of trail condition science to write a system of trail classifications that can be applied to the American River Parkway.

My supervisor has sent me to numerous parts of the parkway to expose me to the dramatically varied landscape and informal trail conditions that exist in the various parts of the river corridor. Trails weave through prickly thickets and curtains of reeds. They cut swaths through otherwise impenetrable walls of star thistle. Trails flow over stretches of rocky riverbeds left dry in these years of drought. It's all of these trails that need to be classified, cataloged and mapped in order to provide a scientific understanding of where recreation can be encouraged and where it must be curbed for the good of wildlife.


Korbi Thalhammer is a sophomore at UC Berkeley studying forestry and natural resources. He is interning at the Sacramento County Department of Regional Parks as a Matsui Local Government Fellow.