Sediment Management on Unpaved Roads

Unpaved roads have the potential to be a significant source of suspended sediment in rural watersheds. The timing and frequency of the sediment loads from unpaved roads is significant in that seemingly small rainfall events can contribute suspended sediment to streams and creeks resulting in elevated turbidity and total suspended solids concentrations. The sediment from unpaved roads has the potential to adversely affect water quality of streams by reducing water clarity and decreasing aesthetics. Also, suspended sediment loads impact benthic habitats through clogging and burying of interstitial spaces of gravel bed stream networks and aquatic biology by clogging fish gills, suffocating eggs and benthic insect larvae.

Proper road construction and maintenance protects water quality during and after agricultural, forestry, and road maintenence activities.

Road Location/Planning

1) Use soil surveys, topographic maps, aerial photographs or site visits to plan road locations to protect water quality.
2) Design roads to avoid or minimize stream crossings.
3) Cross streams at right angles.
4) Where topography permits, locate roads along the contour and along the crest of long ridges.
5) There should be sufficient distance between the Streamside Management Zones (SMZ) boundary and roadway to allow right-of-way maintenance.

Road Construction

1) Use at least the minimum design standard that produces a road sufficient to carry the anticipated traffic load with minimum environmental impact.
2) Remove timber from rights-of-way and deck it outside SMZs.
3) Design roads no wider than necessary to accommodate the anticipated use.
4) Balance cuts and fills to minimize excess excavated material.
5) Place sidecast or fill material above the ordinary high water mark of any stream except where necessary to stabilize stream crossings.
6) Plan and conduct work so that water quality is protected during heavy rain.
7) When needed, use seeding and mulching in a timely manner to reduce erosion.