|Stressor - Land Erosion|
What is Land Erosion?
Land erosion is the process by which material on the surface of the land is dislodged and moved. Land erosion becomes a water quality stressor when the transported materials reach surface waters. The sediment itself is a pollutant when it reaches waters. Land erosion is a natural process that can be greatly increased through human activities. Erosion can be caused by both wind and precipitation; however, precipitation-driven erosion is the primary water-quality stressor in Vermont.
In the precipitation-driven erosion process, soil or other materials are first dislodged from the ground by either the impact of rain hitting the ground, or by being “swept up” by the flow of “sheet runoff water” across the ground surface. Land erosion increases rapidly when vegetation and the intact “duff” or organic outer layer of soil are removed. Erosion rates vary significantly depending on a site’s slope, the inherent erodibility or prior compaction of the soil, as well as the extent and condition of vegetation and antecedent moisture conditions. The pollutant load associated with land erosion is dependent on the amount of pollutants that exist on or in the eroding material. The extent to which eroded material is delivered to a receiving water depends on proximity and the existence of constructed or natural conveyances, such as swales, channels and ditches, pipes, or culverts. Barriers to sheet-flow based erosion, such as riparian buffers, filter strips, stone-lined roadside ditches, or other land treatments, can significantly reduce or even preclude the impacts of land erosion.
How important is Land Erosion?
Available data indicate that the effects of land erosion are widespread throughout the state. The delivery of sediments and associated nutrients has multiple effects on receiving waters, with the intensity of the impacts dependent on the type of sediment involved, the nutrient content of the sediments, and the capacity of the receiving water.
Empirical data are not available to describe the quantity of sediments and nutrients delivered from land erosion separately from those delivered by channel erosion. However, the 2010 statewide water quality assessment suggests that for rivers and streams, 211 miles are impaired due to sediment, with an additional 800 miles stressed. For nutrients, there are 136 river miles impaired, and 498 miles stressed. Among Vermont’s lakes, 100 acres are impaired due to sediment, and an additional ~8,900 acres are stressed (~5,400 of which are in Lake Champlain). As for nutrients, there are 139,800 acres impaired (132,000 acres of which are in Lake Champlain), and ~3,900 acres stressed (hyperlink 305b report).
What objectives are achieved by managing Land Erosion?
Addressing and preventing land erosion promotes several surface water goals and objectives, including:
Minimize Anthropogenic Nutrient and Organic Pollution
Sediments from eroded lands contribute significantly to nutrient pollutant loading. Reducing land erosion can decrease the nutrient load delivered to receiving waters. Minimizing activities that contribute to erosion and implementing best management practices that prevent and control the rate of erosion are the focus of a substantive multi-agency effort to reduce this form of pollution.
Protect and Restore Aquatic, and Riparian Habitat
Excess sediment resulting from land erosion degrades aquatic and riparian habitat. Cover, feeding, and reproductive habitats of aquatic organisms are dependent upon the sorting, distribution and variety of sediment types in lakes, wetlands, and streams. By minimizing land erosion, complex physical habitats that support a diverse assemblage of aquatic and riparian species are maintained. Excessive land erosion will yield uniform, sediment-embedded habitats of considerably lesser quality.
Minimize Toxic and Pathogenic Pollution, and Chemicals of Emerging Concern
Land erosion from excessively applied or poorly incorporated manure results in pathogen releases to surface waters, resulting in potential impacts to recreational uses. However, land erosion is not considered a major delivery mechanism for most toxic compounds, nor for Chemicals of Emerging Concern.
What are the causes and sources of Land Erosion?
The causes and sources of land erosion generally include activities that either eliminate the vegetation that protects soil from erosion, or result in increased runoff volume and velocity. The causes and sources of land erosion include runoff from developed lands; construction activities; agriculture; and forest management. Each of these categories is described in more detail below.
Land erosion from developed lands. Developed land generates more runoff than undeveloped land. Impervious surfaces, including roads (both paved and gravel), parking areas, and buildings prevent precipitation from infiltrating into the ground, and instead produce runoff of sufficient velocity to erode soil and other materials in the flow path. Additionally, developed land often includes a stormwater collection system, or storm sewer system, that effectively routes large areas of impervious system to single points, thus exacerbating the potential for erosion. Erosion is most pronounced where runoff is collected, or concentrated, such as in road ditches, or at outfalls of storm sewer systems. Land erosion due to stormwater runoff from developed land can be mitigated through practices that reduce the volume of runoff, remove pollutants from stormwater, and slow the rate of runoff. Providing appropriate riparian buffers from surface waters can also mitigate the impacts of land erosion from developed land sources.
Land erosion from construction activities. Because construction activities typically result in the loss of vegetative cover, they can produce extremely high rates of soil loss. In addition, altering a site’s topography can result in a concentration of runoff and stockpiling of erodible materials can cause significant erosion. Land erosion due to runoff from construction activities can be mitigated through: practices that reduce the amount of cleared land at a given time as well as reduce the period during which it is exposed or left without permanent cover or vegetation; practices that protect the soil during construction, such as mulching; and practices that slow runoff and filter or otherwise reduce the pollutants from the runoff. Providing appropriate riparian buffers from surface waters can also mitigate the impacts of land erosion from construction sources.
Land erosion from agricultural activities. Agricultural activities including: runoff from impervious surfaces in agricultural production areas, such as barn roofs and concrete barn yards; land disturbance associated with the planting and harvesting of annual crops, such as corn and soy; and unmanaged or poorly managed pasturing, allowing livestock direct access to surface water and wetlands and/or overgrazing and denuded vegetation, can all contribute to land erosion through alteration or removal of vegetation. This leaves soils exposed and alters natural drainage patterns, concentrating flows through ditching or tiling. Similar to runoff from developed lands, land erosion rates are highest where runoff is concentrated into a ditch or similar conveyance. Land erosion due to agricultural activities can be mitigated by following practices to reduce the potential for erosion, such as: expanding “clean water management” to include hydrologic considerations, planting only perennial crops in sensitive areas such as along rivers, ditches, lakeshores and steep slopes, using conservation tillage, planting cover crops, installing “WASCoB’s (water and sediment control basins), excluding animals from surface waters, and implementing rotational grazing systems. Providing appropriate riparian buffers from surface waters also mitigates the impacts of land erosion from agricultural sources.
Land erosion from logging activities. The construction of logging roads, skidder trails, log landings, inadequate protection of stream and wetland crossings, and log transport activities that expose the soil to precipitation, as well as a lack of site maintenance and close-out, can result in land erosion similar to that of construction activities and runoff from developed lands. On a statewide basis, logging activities result in less land erosion than results from runoff from developed lands and construction activities, however, when erosion from logging operations is allowed unchecked, intense localized impacts occur. Land erosion due to logging activities can be mitigated by following practices that properly locate and construct logging roads, skidder trails, stream crossings, and log landings, as well as restrict the use of mechanized equipment to times when there are sufficiently dry or frozen conditions. Providing appropriate buffers from surface waters can also mitigate the impacts of land erosion from logging sources.
Monitoring and assessment activities to assess effects of Land Erosion
Existing monitoring and assessment activities that consider the causes and effects of excessive land erosion are listed below. Full descriptions of the programs that carry out these activities may be found in the State Monitoring and Assessment Strategy and in Appendix D.
- VT DEC’s Monitoring and Assessment Program carries out a comprehensive surface water monitoring strategy aimed at understanding the relative importance of sedimentation and nutrient pollution in Vermont surface waters.
- VTDEC’s Lake Assessment Program and Citizen Lake and Watershed Surveys particularly note erosion occurring along lakeshores.
- VTDEC River Management Program
- Stream Geomorphic Assessments
- Bridge and Culvert Assessments
- VTDEC Ecosystem Restoration Program Program
- Stormwater Infrastructure Mapping
Illicit Discharge Deection and Elimination Surveys
- The LaRosa Partnership Program of VTDEC supports citizen scientists who are interested in monitoring the condition of waters in their watersheds.
- The Natural Resources Conservation Service has developed a metric of soil loss called “T,” or tolerable soil loss. This is tracked within NRCS databases, and is assessed on a farm-by-farm basis. As a pre-condition for enrolling in many of the cost-share programs offered by NRCS, agricultural producers are required to have a plan in place that reduces soil loss to T by applying best management practices. The T-factor was initially developed out of concern for preserving agricultural productivity, and represents the maximum annual soil loss expressed in tons per acre per year that can occur on a particular soil while sustaining long-term agricultural productivity. It is important to remember that T is based on agricultural productivity and does not directly consider water quality impacts that such soil loss would have on a receiving water.
- Lake Champlain Basin Program – supports the Long-Term Water Quality and Biological Monitoring Program on Lake Champlain, which is operated jointly by the States of Vermont and New York. The program measures TSS, phosphorus, nitrogen and many other parameters in the lake and its tributary rivers. All chemical analyses are conducted by the Vermont DEC Laboratory. The tributary monitoring results are analyzed with data from the network of stream flow gauges in the basin operated by the U.S. Geological Survey. The monitoring results are updated annually on the Lake Champlain Long-Term Monitoring Program website where the data and graphical summaries are freely available. The Basin Program also supports individualized watershed-specific sampling efforts as needed.
Key Monitoring and Assessment Strategies to Address Excessive Land Erosion
Conduct integrated analysis of biomonitoring and land use data to identify trends in and extent of land erosion.
LiDAR, or “Light Detection and Ranging” is a method of very high-resolution elevation and contour mapping. Obtain statewide “LiDAR” data and use this to identify areas of localized erosion.
Complete critical source area analysis, evaluating the relative erosion potential from different areas across the state.
A major concept promoted through agricultural management programs is that soil loss should be maintained within a tolerable level, known by the farming community as “T.” “T” is presently based on soil protection, and not water quality protection. Alternatives for a water quality-based “T” value would benefit both soil protection and surface water quality.
Technical assistance programs to address Land Erosion
Existing programs that provide technical assistance in various aspects of managing the causes and sources of excessive land erosion are listed below. Full descriptions of these programs may be found in Appendix D.
- Lake Shoreland Management Program
- USDA NRCS Highly Erodible Land Conservation
- USDA Conservation Technical Assistance
- AAFM ARS Program
- Better Backroads Program
- Forests, Parks and Recreation Watershed Forestry and Urban and Community Forestry Programs
Key Technical Assistance Strategies to Address Land Erosion
- Develop and maintain the capacity to technically assist landowners, municipalities, land developers, agencies, and organizations in the implementation of sound land use practices, including shoreland management.
- Continue to provide technical assistance to town road maintenance programs through the Better Backroads Program to encourage proper ditch design and maintenance, and dirt road design specifications that minimize land erosion.
- The FPR Division of Forests staff provides technical assistance to forest landowners and loggers to help them comply with Vermont’s Water Quality and the Heavy Cutting Laws.
- The Vermont Agency of Agriculture, Food & Markets - Division of Agricultural Resource Management and Environmental Stewardship offers a host of programs to protect water resources. These programs are both regulatory and voluntary in nature and are designed to be an efficient approach for Vermont farmers to protect their environment.
Regulatory programs to address Land Erosion
Existing programs that regulate activities causing land erosion are listed below. Full descriptions of these programs may be found in Appendix D.
- VT DEC Stormwater Management Program
- AAFM Accepted Agricultural Practices AAPs
- AAFM Large Farm and Medium Farm Operation Permitting Programs
- Accepted Management Practices for Logging AMPs
- VTrans Access Management Permit Program
Key Regulatory Strategies to Address Land Erosion
Continue to implement the State’s stormwater regulatory programs. The 2009 Lake Champlain TMDL implementation plan also identified addressing stormwater runoff from developed lands as one of the top ten steps for reducing phosphorus pollution in Lake Champlain. The State’s stormwater program is the primary mechanism for regulating discharges from impervious surfaces and construction sites. Regulatory oversight of new development is necessary to ensure that stormwater discharges do not contribute to excess land erosion.Conduct an analysis of existing jurisdictional thresholds (e.g. 1 acre of disturbed land) to determine if existing programs are sufficiently protective, particularly in sensitive areas such as within river corridors, or lakeshores.
Further coordinate Aency of Agriculture, food and Markets regarding implementation of Accepted Agricultural Practices (AAPs), which, are intended to reduce, pollutants associated with common agricultural activities. The AAPs require, among other things, setbacks along surface waters. The AAPs are the State’s primary regulatory for any agricultural operation that does not trigger the regulatory thresholds of the medium- or large-farm operation permitting program; the AAPs apply to all farm operations, regardless of type or size.
Continue development of a Consolidated Animal Feeding Operation permit to somplement existing Medium (MFO) and Large Farm Operation (LFO) permitting programs as administered by the Agency of Agriculture.
Coordinate with the Department of Forests and Parks to evaluate opportunities for enhanced surface water protection under the Accepted Management Practices (AMPs) for Maintaining Water Quality on Logging Jobs in Vermont. AMP’s define allowable activities within river corridors and prescribe baseline practices to reduce land erosion.
Funding programs to address Land Erosion
Existing funding programs that support projects to address the causes and sources of land erosion are listed below. Full descriptions of these programs may be found in Appendix D.
- Ecosystem Restoration Ecosystem Restoration Grants
- USDA-NRCS EQIP program
- AAFM Farm Agronomic Practices (FAP) and, Nutrient Management Plan Incentive Programs
- USDA-NRCS/AAFM Conservation Reserve Enhancement Program
- Better Backroads Grant Program
- Clean Water State Revolving Fund
Key Funding Strategies to Address Land Erosion
The Ecosystem Restoration Grant program is the cornerstone of the Clear (C&C) Program’s on‐going efforts to reduce surface water pollution from phosphorus and sediment. C&C is specifically interested in proposals designed to improve water quality, including but not limited to projects that: improve stream stability, incorporate the science of fluvial geomorphology in river corridor management decisions, protect against flood hazards, and improve in‐stream and riparian habitat; mitigate the effects of hydrologic modification (stormwater runoff) associated with urban development; protect and restore riparian wetlands; re‐establish lake shoreline native vegetation and related shoreline erosion corrections; directly address in‐lake (internal) phosphorus loading conditions; and enhance the environmental and economic sustainability of agricultural lands.
The AAFM, Division of Agricultural Resource Management and Environmental Stewardship offers several funding programs to promote agricultural best practices that include very low cost-share requirements.
The Vermont Better Backroads Program provides direct funding to municipalities for road and culvert assessments and to promote improvements that are recommended by these assessments.
Information and Education programs to address Land Erosion
Existing programs that inform and educate the general public about the causes and effects of land erosion are listed below. Full descriptions of these programs may be found in Appendix D.
- Lake Shoreland Management Program
- Ecosystem Restoration Program
- Lake Champlain Basin Program
- UVM Extension
- Chittenden County’s Regional Stormwater Educational Program (RSEP) and associated Stream Team project.
As described above there are a broad suite of technical and financial assistance programs, as well as regulatory measures that are designed to address land erosion. By in large these efforts target specific practices, activities or locations, and do not provide broad-based outreach to the general public about the causes and effects of land erosion. While it is unlikely that the typical Vermont homeowner will have substantial and uncontrolled erosion occurring in their backyard, each and every homestead contributes to the changes in hydrology and overland flow that can cause or contribute to land erosion.
The Lake Shoreland Management Program works with lakeshore owners and municipalities to educate them about shoreland sources of erosion and to offer materials and technical assistance to correct and avoid problems.
Towns and other entities subject to MS4 stormwater permitting develop and distribute education about the source of stormwater and residential BMPs for protecting surface waters from stormwater and subsequent land erosion. To meet permit criteria, they provide information on websites, displays, commercials, and factsheets.
In municipalities subject to mandatory stormwater pollution control efforts at the individual parcel level (e.g., where total maximum daily loads and residual designation authority has been imposed), considerable education and outreach effort is provided to residents on how to comply with the stormwater control requirements. Materials developed for that purpose should be made available to residents and officials in other municipalities, coincident with a coordinated outreach effort.