Using BMPs to protect - water quality
The role of forests in stabilizing soils and protecting watersheds is universally recognized. Best Management Practices (BMPs) by definition are practical and efficient technologies to protect water quality. When a forest is disturbed the potential for erosion and degrading water quality increases. Water quality is affected by sediment levels, water temperature, streamflow, nutrient levels, dissolved oxygen levels. BMPs can minimize, eliminate or reverse water quality impacts.
The following forest management practices require BMPs regardless of whether the purpose is for timber, wildlife, recreation, aesthetic or other reasons:
- Road and trail construction, maintenance and use
- Timber harvesting and skidding logs to loading areas
- Mechanical equipment operation
- Controlled burning, particularly fireline construction
- Site preparation by hand, chemical or mechanical methods
- Fertilizer application, particularly near water bodies
- Minor drainage alterations
- Pesticide applications
The BMPs you select to manage your property will be a unique mix. Prior to beginning any activities, you need to walk your property and identify such things as restrictive/sensitive zones around water bodies and streams; soil types; areas of steep slopes; unique natural areas; and wildlife habitats.
Roads, trail and log decks should be kept at the minimum number to allow efficient timber harvesting while protecting water quality. Determine what type of logging equipment will have the least environmental impact on your forest.
Site preparation and regeneration planning
Select the practice(s) which accomplish the required vegetation control and seedbed preparation with the minimum soil/site impact.
Fertilizer or pesticide application planning
From a planning standpoint, learn the chemical characteristics, topography, soils, drainage, and other factors that might be important for preventing water pollution during application.
Roads, trails and firelines planning
Roads, trails and firelines are the major source of sediment from forestry operations. A well-planned road, trail and fireline system minimizes the number of stream crossings, fits the topography of the site, locates the roads, trails and firelines outside of critical streamside areas and uses appropriate drainage and water control structures. Hand constructed firelines should be used on steep terrain.
Streamside Management Zones (SMZ)
An SMZ is an area or zone along an intermittent or perennial stream (which flows more than 30 percent of the year) where extra precaution is used during activity. Its purpose is to slow and spread surface water flow, and trap and filter suspended sediments before they reach the stream channel. SMZs also provide stream shade and function as buffers to filter and capture fertilizers, pesticides, and other potential pollutants.
The recommended width of an SMZ will vary from 50 to 200 feet depending on the stream, the soils, and the topography. Limited tree harvesting is allowed in the SMZ if trees can be felled away from the stream channel and removed with extreme care – leaving the forest floor and ground cover vegetation largely undisturbed. Heavy equipment use is discouraged in the SMZ.
Effective SMZ's have the following characteristics:
- Wide enough to capture and filter soil and other pollutants before they reach the stream or water body
- Has no more than 40 percent bare ground, evenly distributed
- Wheeled or tracked-type equipment is excluded
- Enough shade is retained to maintain stream shade and temperature – normally 75 percent of the pre-harvest level
- Broadcast pesticide or fertilizer application is prohibited
- Controlled burning is not allowed
- Chemicals, hazardous wastes or fuels are stored outside the SMZ
- Roads and trails are located outside of the SMZ, except where stream crossings are essential, or where physical or topographic restrictions require the placement of a road in the SMZ
- Bare soil areas are promptly re-planted or mulched
- Sawmills, log storage areas and log decks are not located inside the SMZ
BMPs for fertilizer and pesticide application
Assess the rates, timings and application technologies (delivering the right amount of chemical to the right place at the right time) for optimum effectiveness, and minimal water quality impact.
Applicable BMPs for fertilizers include:
- Perform a soil test to determine fertilizer needs
- Carefully apply fertilizer, avoiding direct and indirect entry of fertilizer into streams or water bodies.
Applicable BMPs for pesticides (herbicides, insecticides, fungicides and rodenticides) include:
- Apply only according to label directions, using the minimal rate to accomplish the desired result
- Carefully apply pesticides, avoiding direct and indirect entry of pesticides into streams or water bodies
- Do not broadcast apply in SMZs; utilize injection, stump treatment or directed spray in areas immediately adjacent to open water
- Comply with applicable federal and state regulations for buffer zones/filters strips, such as around roads, schools, residences, etc.
- Mix chemicals and clean tanks only where spills will not enter streams, lakes or ponds
- Maintain and adjust application equipment to prevent spillage and excessive application
- If a spill should occur, immediately contain it (Note: some spills require immediate notification of appropriate authorities)
- Dispose of containers according to label recommendations and applicable state laws
- If hiring a custom applicator, require a written contract and proof of appropriate licenses, insurance and bonding of the contractor
- Aerial application will cease when 1) wind speeds exceed six miles per hour; 2) temperature reaches 90 degrees F; 3) in advance of/or during unstable weather patterns
- Aerial and ground equipment and techniques used are designed to assure maximum control of the spray swath (width) with minimal drift
BMPs for roads, trails and firelines
A road system, temporary or permanent, provides access for timber harvesting and management activities, recreation or wildlife enjoyment Improper road construction and maintenance is the major cause of erosion and sediment from forestry activities.
Well-designed road and trail systems have the following characteristics:
- Roads should be allowed to stabilize/settle before use
- Roads should be as narrow as possible
- Roads should be on gentle slopes, avoiding flood plains when possible
- Roads should be placed outside of SMZs
- Roads should cross streams at right angles using bridges, culverts or constructed fords
- Roads should be daylighted to maximize drying and promote vegetation
- Water should be effectively controlled through diversion or drainage
- Frequent inspection and maintenance
Planning will identify the specific BMPs that will assure that your road and trail system is water quality friendly.
Road BMPs include:
Water turnouts are ditches, trenches or waterways that divert water away from the road surface. They carry water into an undisturbed area where the flow slows and sediments are filtered and trapped.
Cross-road drainage by culvert
Cross-road drainage is the transfer of water across or under the road, usually by a round culvert. It is used on any road or trail where storm water runoff, ditch-toditch transfer, slope or overland seepage might cause erosion. Pipe culverts 14 inches or larger are normally installed on permanent roads and trails.
Broad-based drainage dip
Broad-based dips create a reverse uphill slope in a road surface, effectively slowing and moving water off the road surface into an undisturbed adjacent area.
Rolling dips are a rounded hump which creates a reverse slope and turnout. They are often used in skid trails where logs are skidded (dragged) to a log loading area (deck). The rolling dip provides cross drainage and slows water flow and holds up better under heavy traffic.
Water bars are a combination mound/trench built into a road or trail and sloped slightly downslope to move water off the road surface into an undisturbed, adjacent area. Water bars are usually installed after the road is no longer used.
Forest harvesting and management activities often require crossing intermittent or perennial streams. Plan to use as few crossings as possible. Road and trail approaches to stream crossings must have good surface drainage that turns water into undisturbed areas away from the stream course.
Streams may be crossed in several acceptable ways:
Considered expensive, they are usually used on permanent roads. However, following use on temporary roads and trails, they can be carefully removed to minimize soil disturbance. It is important that culverts be of adequate diameter to handle above-normal water flows; long enough to extend slightly upstream and downstream from the crossing, and be installed with a 2-4 percent downstream angle to aid in flushing out debris. A single culvert, sized to handle the water flow, is less likely to clog than several smaller stacked culverts.
Backfill material should be free of debris and the culvert should be covered with fill to a depth of one-half the diameter of the culvert, or a minimum of one foot.
Temporary or permanent, there are numerous styles of bridges used to cross streams where culverts won't handle the stream flow. Bridges should be built to handle heavy loads using the proper type, size and materials. Professionals can help design your bridge. Stream channel and stream banks should be protected from erosion during construction by continual mulching or vegetated ground cover. Abutments and headwalls may be needed to handle flood conditions and stabilize the approaches to the crossing area. Use vegetation or ground cover to stabilize road approaches and road banks.
For temporary or minimum-use crossings, fords should only be used where the stream has an applied or existing firm base. Riprap stone, brush, poles or other materials stabilize the road or trail approach to a ford, and the streambed to protect the stream channel. Stone is usually not removed after road use ceases, but poles, brush and other materials are.
Site preparation and regeneration BMPs
The condition of the tract, the desired species you wish to regenerate and environmental concerns including water quality need to be addressed. SMZs, road layout and design, equipment limitations, and management options should be planned in detail and documented on the ground and/or on a map. There are numerous options for site preparation including bulldozers (chopping, discing, rake and pile, bedding, furrowing, scalping), hand tools, herbicides and fire. Site preparation techniques which create bare soil conditions increase the risk of erosion.
Site prep and regeneration BMPs include:
- Use the least site disturbing activity to accomplish the planned result
- A SMZ should be maintained on all perennial and intermittent streams
- Soil disturbance in ephemeral (flows less than 30% of the year) stream channels should be minimized or avoided
- On steep terrain and/or on fragile soils, herbicides, controlled fire or manual site preparation is preferred over heavy equipment
- No debris, oil or other waste should be placed in or close to streams
- Machine planting of trees should be done on the contour. Steep slopes should be hand planted
At the conclusion of any silvicultural activity:
- All temporary stream crossings should be carefully removed
- Roads, trails and firelines should be inspected to be certain that all water control structures are in place and functional
- All toxic waste, tires, oil and trash should be removed and properly disposed
- Mulch, brush or vegetative cover should be provided on bare soil areas to stabilize the area and reduce the potential for surface runoff and accelerated erosion