How do I Install a Water Bar Drainage System?

A water bar is a drainage structure that may be used to divert the flow of water on a grade of no more than 20 percent.

Wood Water Bars

With proper construction and maintenance, water bars can be a reliable way to redirect surface water on trails.With proper construction and maintenance, water bars can be a reliable way to redirect surface water on trails.
Most commonly, water bars are built on trails or backcountry roadways to help reduce soil erosion caused by water flow. Water bars are best constructed with rock or peeled logs and require ongoing annual maintenance to ensure that the structure continues to work properly and does not become a safety hazard for hikers or horsemen.

Determine where along the trail water bars will be placed and mark each area with a line at a 45 to 60 degree angle across the trail. Dig a trench, following the angle, along the premarked line. Water bars must sit at the appropriate angle to reduce the amount of silt caught by the structure.

Install a 6- to 8-inch diameter peeled log, meaning a log that has been stripped of its bark, into the back wall of the trench. Bury the log so that half of the log is embedded in the soil and the other half exposed. Make sure that the log sits in line with the angle of the trench and spans the width of the trail.

Secure the log in place using stakes or large rocks at the uphill end of the log. Use soil and rocks to fill in the area around the downhill end of the log, leaving a maximum of 1 to 2 inches of wood exposed.

Rock Water Bars

Dig a trench across the width of the trail at a 45 to 60 degree angle, in the same manner as you would to construct a wood water bar.

Locate enough rocks to span the width of the trail. Ideally, rocks used in water bar construction should be rectangular in shape and just small enough that they can still be reasonably carried by an adult.

Bury the rocks into the downhill side of the culvert, leaving one-third of the rock's surface above ground. Arrange the rocks to that they touch one another and fill any gaps between them with smaller rocks so that water is unable to flow between the rocks and cause erosion.

Gather soil to back fill the downhill area of the water bar, creating a gradual ascent to the water bar and reducing the danger of anyone using the trail accidentally tripping or slipping on exposed rocks.

Things You Will Need

  • Shovel or McLeod
  • Peeled logs
  • Large rocks