It is important to control erosion in forests
Best Management Practices During a Timber Harvest

Crossing streams to minimize erosion

This web article explains how loggers and landowners can cross streams during a timber harvest while minimizing sediment runoff and protecting the stream's aquatic life.

Basic concepts:
1. Make every effort to avoid streams and minimize stream crossings
2. Cross streams directly when necessary
3. Build and maintain effective structures to protect the stream bottom and banks

Landowners, foresters, and loggers will often work around three kinds of streams:

- Creeks that flow constantly
- Smaller streams that occasionally dry down or freeze over
- Dry channels that fill with intermittent flow from snowmelt or rainwater

Constant flow
Intermittent flow
Dry channel

All three types of streams require some kind of protection during logging. Because they are variable, soil erosion can be unpredictable. Rutting on the sides or bottom of streams is harmful and should be avoided. Landowners are partly responsible for ensuring logging activities do not cause environmental harm to streams and lake waters.

Best management practices for crossing streams

Refrain from crossing streams when possible.
During the planning stage, arrange the logging activity to cross streams as few times as possible or not at all. Refrain from logging in the vicinity of streams or stream crossings.

Obtain permits to cross streams.
The first step is to call the county Soil and Water Conservation District office and the regional NYS DEC office and ask for staff who handle water quality protection permits. A Protection Of Waters Permit is required if the timber harvest somehow crosses these protected streams, whether temporary or permanent.

According to the NYS DEC, all waters of the state are provided a class and standard designation based on existing or expected best usage of each water or waterway segment.

  • The classification AA or A is assigned to waters used as a source of drinking water.
  • Classification B indicates a best usage for swimming and other contact recreation, but not for drinking water.
  • Classification C is for waters supporting fisheries and suitable for non - contact activities.
  • The lowest classification and standard is D.

Waters with classifications A, B, and C may also have a standard of (T), indicating that it may support a trout population, or (TS), indicating that it may support trout spawning (TS). Special requirements apply to sustain these waters that support these valuable and sensitive fisheries resources. Streams and small water bodies located in the course of a stream that are designated as C(T) or higher (i.e., C(TS), B, or A) are collectively referred to as "protected streams," and are subject to the stream protection provisions of the Protection of Waters regulations.

Classified streams are protected year-round
Classified stream "C" in the Finger Lakes region

Small ponds and lakes with a surface area of 10 acres or less, located within the course of a stream, are considered to be part of a stream and are subject to regulation under the stream protection category of Protection of Waters.

To determine the classification and standard of a given watercourse, contact the Department of Environmental Conservation regional office responsible for the area in which the watercourse is located.

The DEC can also issue a more straightforward permit through the Standard Activity Permit Process (SAPP). These are appropriate for simple logging jobs that do not involve many stream crossings and will help ensure you are not at risk of violating Environmental Conservation Laws. A DEC Forest Ranger, can assist you with questions about SAPPs.

In some cases, the building of new logging roads may be considered a construction activity, depending on how long and wide the new roads are. If this applies to the planned timber harvest site, a DEC permit related to Stormwater Discharges from Construction Activities may be needed. This permit calls for a stormwater pollution prevention plan in compliance with New York's Environmental Conservation Law. Contact the permit division at your regional DEC office, or check with county Soil and Water Conservation District staff.

Cross small streams if the season and weather conditions permit
Very small streams are sometimes dry or frozen, making crossing less harmful. If the weather becomes warmer or rainy, refrain from crossing small streams.

Cross stream directly, not on an angle.
Do not skid logs down a stream course.

Cross streams where the stream bottom is stable and the banks are low and intact.

If a stream crossing is necessary, install an appropriate structure - a bridge, a culvert, or a pole ford - to minimize rutting and erosion.

bottom of culvert is same as creek bedConstruct bridges to minimize sediment erosion and maintain stream flow.
Inspect and photograph a planned stream crossing, noting potential obstacles, steep slopes, or other erosion hazards. Select materials that will not harm aquatic life. If the landowner would like a permanent bridge installed, construct it to withstand a 50 to 100-year rainstorm or flash flood. Consult with the county Soil and Water Conservation District technicians to assist with temporary or permanent bridge construction.

Construct culvert crossings to minimize erosion.
Use arch-type culverts to maintain stream bottom form and reduce sedimentation. Size the culvert(s) to handle current and storm flows of water. Consult with the county Soil and Water Conservation District technicians to assist with proper installation of culverts. Failure to properly size a culvert can lead to washed out roads and inaccessible forest land.

Sides of culvert stabilizedStabilize fords with rock or pole timber.
Fords that cross intermittent streams and dry washes can be protected with small logs placed side-by-side, small diameter pipe, or clean rock. These materials will prevent cross rutting and ponding within the logging trail. They should be removed immediately following the timber harvest.

Stabilize the sides of culverts to prevent erosion from the road.
Make sure the sides of the culvert are compacted, and / or reinforced with cull logs. Chain the culvert or bridge to a nearby tree so it can be retrieved if it is washed away.

Where a logging trail approaches a stream crossing, divert water into the forest.
If water collects and flows down a logging trail, it should be diverted off to the surrounding vegetation with a broad-based or rolling dip before it reaches the culvert or bridge. Do not allow water on a forest road to flow directly into a stream, as it will inevitably carry sediment. If it flows off to the surrounding vegetation, the water will filter through the streamside zone, trapping the sediment. The deck of the bridge (or culvert cover) should be higher than the approach road to improve drainage away from the stream crossing.
Cull logs can be embedded in the bridge approach, perpendicular to the roadway, reinforcing the sides.

Construct stream crossing structures during low flow periods.

Use temporary bridges to cross streams when appropriate.
If a selected forest road will be unmaintained after the harvest, a temporary bridge will protect the stream banks without incurring significant costs.

Monitor stream crossing structures during the timber harvest for plugging.
Bridges and culverts should not become filled with sediment or clogged with debris or beaver activity. This would create a significant erosion hazard as the water would then flow around or over the structure.

Page 41 in the NYS Best Management Practices Field Guide lists culvert size recommendations.


Pole ford drawing from Wisconsin's Forestry Best Management Practices for Water Quality.
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Please cite source: Cornell Cooperative Extension, 2004
Written by James Ochterski, CCE - Schuyler County