Old roads can cause fish-choking erosion

Most people have no idea how much water rushes out of the mountains in the spring. Gullies that are dry when the hikers and bikers arrive in June were rumbling with runoff in May.

But an old road carved across a hillside can be a good place to learn about one of the most serious water quality issues on national forests.

When a road is built, engineers install bridges and culverts to funnel streams and runoff under the road.

When a road is abandoned, the culverts must either be maintained or removed so the drainage can be restored to a natural condition to prevent washouts.

“Culverts are great when they’re working, but once they plug up, they’re a disaster,” said Rusty Gahr, Bonners Ferry Ranger District trail maintenance worker.

Gahr was surveying two cases in point within a mile of each other: massive washouts on the Bottleneck-Snow lake trail at Bottleneck Creek and Corner Creek.

For reasons that probably had something to do with cost, the culverts were not removed years ago when the road was closed.

The obvious consequence was that horses will not be able to pass through the deep washout gouges in the hillside until new trail is built later this summer.

“What’s not so obvious to most people is that all that material is being washed down the mountain into the streams below where fish are trying to live,” Gahr said.

“It’s a continuing story,” said Pat Hart, the district’s trail maintenance manager. With thousands of miles of abandoned roads on the forests and a dearth of money for maintenance, “It’s not a matter of whether they’re going to blow out, it’s just a matter of when.”