BMP Field Manual
Chapter 1 - Introduction
Clean water is essential to Wisconsin's economy and rich quality of life. Lakes and streams provide habitat for wildlife, fish and other aquatic species. Our forests play a vital role in purifying and maintaining clean water for streams, lakes and groundwater. The most practical and cost-effective method to assure that forestry operations do not adversely affect water quality in Wisconsin is through the use of the voluntary "best management practices" (BMPs) described in this manual. These BMPs are voluntary in the sense that they are not legally mandated. However, the Wisconsin Department of Natural Resources (DNR) strongly encourages their use by all Wisconsin forest landowners, land managers and forestry professionals.
Several categories of public and private landowners in Wisconsin already use forestry BMPs to guide their management activities. For example, the DNR requires the use of BMPs on forested lands owned by the DNR and encourages counties to incorporate them into their forest management plans. Cooperating consultant foresters are required to manage private lands in a manner that matches the DNR's standards for DNR lands. Managed Forest Law and Forest Stewardship management plans must incorporate BMPs to control soil erosion that adversely affects water quality. Also, several pulp, paper and forest industry companies have adopted these BMPs as part of their corporate land management policies.
It is U.S. Department of Agriculture - Forest Service policy to promote and apply approved best management practices for control of nonpoint sources of water pollution. The Chequamegon and Nicolet National Forests support the best management practices developed by the Wisconsin Department of Natural Resources.
In addition to the BMPs described in this manual, you should be aware of existing municipal, county, state and federal regulations relating to forest management and water quality. (See Permits and Regulations.)
This manual can help guide you when making decisions about management activities on your land. Applications of BMPs may be modified for specific site conditions with guidance from a forester or other natural resource professional if modifications provide equal or greater water quality protection, or if the modification has no impact on water quality.
You can get professional advice on BMPs and all forest management activities from natural resource professionals such as:
- Consulting foresters
- Industrial foresters
- Wisconsin DNR foresters, fish managers, and water quality staff
- USDA Natural Resources and Conservation Service staff
- County Land Conservation Department staff
One of the biggest threats to water quality in the United States is nonpoint source pollution. Nonpoint source pollution occurs when surface water runoff from rainfall or snowmelt moves across or into the ground, picking up and carrying pollutants into streams, lakes, wetlands or groundwater. Soil becomes a nonpoint source pollutant when water runoff carries large amounts of soil into a waterbody. Best management practices are practical and cost-effective ways to prevent or reduce nonpoint source pollution.
Nonpoint source pollution is the source for about half of all pollutants entering our nation's waters. Three to 9% of all nonpoint source pollution comes from forestry practices nationwide. Because Wisconsin is relatively flat, only about 3% of the state's nonpoint source pollution comes from forestry practices. While 3% sounds small, localized nonpoint source pollution can be significant. And the cumulative effects of all sources can seriously degrade water quality in a drainage system.
Sediment is the primary pollutant associated with forestry activities, especially at stream crossings for forest roads and skid trails.
Forest management activities can generate the following forms of nonpoint source pollution:
- Sediment. Forest floor vegetation and organic debris protect the soil from the erosive action of falling raindrops and runoff. Forestry management activities, such as road building, can remove this protection. This can lead to erosion of the soil, creating sediment. When sediment is carried away in runoff and deposited elsewhere, sedimentation occurs. Without using appropriate BMPs on exposed and sloping land, the soil will likely erode and may wash into a body of water. Sediment is the primary pollutant associated with forestry activities, especially at stream crossings for forest roads and skid trails.
In the natural world, sedimentation is a slow, naturally occurring process. However, human activities often speed it up. The result can be large amounts of sediment accumulating in lakes, streams and wetlands that speed up the aging of lakes and bury fish spawning grounds and aquatic plants. These plants are a source of food and habitat for fish and other aquatic organisms.
Accumulating sediment also constricts naturally flowing channels, leading to increased stream bank erosion and possible flooding. Suspended sediment can cloud the water, reducing the hunting success of sight-feeding fish; it can also damage the gills of some fish species, causing them to suffocate.
- Organic Debris. Leaves and large woody debris (generally large fallen logs, at least 12 inches in diameter with root ball attached) that naturally fall into streams can greatly benefit aquatic ecosystems. However, too much organic debris deposited in a short time can harm water quality. This can occur during logging when tree tops and branches fall or wash into streams. Too much decomposing matter in streams can decrease dissolved oxygen in the water, which fish need to thrive and reproduce.
- Nutrients. Nutrients such as nitrogen and phosphorus exist naturally in forest soil and can enter waterbodies if the soil erodes into water. Also, if fertilizers are used in forest management, they can wash into waterbodies in runoff. Excessive amounts of nutrients may cause algal blooms in lakes and streams, which can reduce levels of dissolved oxygen in the water to below what fish and other aquatic species need to survive.
- Temperature. Some sunlight filtering through trees is healthy for many streams. It can promote plant growth (food) in the water and foster healthy ground vegetation along shorelines. However, when trees and the shade they provide are removed along most small streams, peak mid-summer water temperatures climb as a result of increased solar radiation. This can eliminate cold water fish, reduce dissolved oxygen and affect the metabolism and development of fish.
- Chemicals. Pesticides (herbicides, insecticides and fungicides) help control forest pests and undesirable plant species. But when applied improperly, pesticides can be toxic to aquatic organisms. Also, fuel, oil and coolants used in harvesting and road-building equipment must be handled carefully to avoid water pollution.
- Streamflow. Timber harvesting can increase peak streamflow which increases chances for flooding, streambank erosion and sedimentation. When 60% or more of a basin's area consists of trees less than 15 years old, snow can melt at several times the rate that occurs in forests over 15 years of age. This increase in snowmelt can increase peak streamflows.
If timber harvesting equipment compacts a large area of the forest soil, water infiltration into the soil is reduced and surface runoff into streams increases. This also reduces water percolation through the soil to recharge groundwater. Groundwater provides cool, clean water to lakes and streams, maintaining steady streamflows and lake levels throughout the summer.
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