Home 5. Protect Wetlands

Protect Wetlands Locally

Local governments play a key role in filling the gaps in wetland protection, because they have primary responsibility for local land use management. Local action is particularly critical in states that do not have comprehensive wetland protection programs.  Protect Wetlands Using Regulatory or Voluntary Measures provides a review of regulatory and non-regulatory options for local governments. Ideally, a combination of approaches will be used.

Managing wetlands at the watershed scale can help minimize indirect impacts to wetlands.  Direct impacts to wetlands include the removal or addition of material such as dredging, filling, or draining that are largely regulated through the federal and state wetland permitting process.  Indirect impacts such as altered hydrology, increased pollutant loadings, and buffer encroachment caused by urbanization are summarized in Wetlands & Watersheds Article 1.  Using a watershed approach allows communities to make better choices about preserving the highest quality wetlands, protecting the most vulnerable wetlands, and finding the best sites for wetland restoration.  Wetlands & Watersheds Article 2 provides detailed information on using local watershed plans to protect wetlands.

 

Protect Wetlands Using Regulatory or Voluntary Measures

Communities vary greatly in their size, technical and financial resources, development review process, and prior experience in wetland management and watershed planning.  A menu of different wetland protection techniques that communities can choose from to protect wetlands from direct and indirect impacts is provided in Table 5.1. 

The protection techniques are organized by the eight tools of watershed protection that represent a comprehensive approach to protect wetlands in watersheds facing land development (derived from Wetlands & Watersheds Article 3). The eight tools roughly correspond to the stages of the development cycle including initial land use planning, site design and construction, and ultimate occupancy and long-term maintenance.  Each of the eight tools should be specifically applied to protect unique wetland resources in watersheds that may be vulnerable to impacts from future development.  Communities should examine the numerous techniques within each category that best protects wetlands identified as priorities.  Some techniques are more restrictive than others, and the choice of techniques depends on the future wetland protection needs in the community, as well as the capacity of the community to implement the techniques.

Click on the links in Table 5.1 below to read a description of each regulatory and voluntary wetland protection measure, as well as case studies as available and additional information. Wetlands & Watersheds Article 3 provides more detailed information about each approach.

Table 5.1. Regulatory and Voluntary Wetland Protection Measures

Watershed Protection Tool

How to Apply the Tool to Protect Wetlands

Regulatory / Voluntary Measure

1. Land Use Planning

Incorporate wetland management into local watershed plans

Both

Adopt a local wetland protection ordinance

Regulatory

Adopt a floodplain, stream buffer, or hydric soil ordinance to indirectly protect wetlands

Regulatory

 2. Land Conservation

 Identify priority wetlands to be conserved

Voluntary 

 Select techniques for conserving wetlands

Both 

 3. Aquatic Buffers

Require vegetated buffers around all wetlands

Regulatory

Expand wetland buffers to connect wetlands with critical habitats

Regulatory

Increase stream buffer widths to protect downstream wetlands

Voluntary

 4. Better Site Design

Encourage designs that minimize the number of wetland crossings 

Voluntary

Encourage or require site design techniques to protect wetlands

Voluntary

 5. Erosion and Sediment Control

Require perimeter control practices along wetland buffer boundaries

Regulatory

Encourage more rapid stabilization near wetlands

Voluntary

Reduce disturbance thresholds that trigger ESC plans

Regulatory

Increase ESC requirements during rainy season

Regulatory 

Encourage use of site fingerprinting or construction phasing

Voluntary 

Increase frequency of site inspections

Both

6. Stormwater Treatment

Prohibit use of natural wetlands for stormwater treatment

Regulatory

Restrict discharges of untreated stormwater to natural wetlands

Regulatory

Discourage installation of stormwater treatment practices within wetland boundaries

Voluntary

Discourage constrictions at wetland outlets

Voluntary

Encourage progressive stormwater management techniques

Voluntary

Develop special sizing criteria for stormwater treatment practices

Regulatory

Promote effective stormwater treatment practices to protect downstream wetlands

Voluntary

 7. Non-Stormwater Discharges

Conduct illicit discharge surveys for all outfalls to wetlands 

Voluntary 

Actively enforce restrictions on dumping in wetlands and their buffers

Regulatory 

Require enhanced nutrient removal from on-site wastewater treatment systems

Regulatory

Require regular septic system inspections

Regulatory 

8. Watershed Stewardship

Incorporate wetlands into watershed education programs

Voluntary

Post signs to identify wetlands, buffers, and wetland drainage area boundaries

Voluntary

Manage invasive wetland plants

Voluntary

Establish volunteer wetland monitoring and adoption programs

Voluntary

Encourage wetland landowner stewardship

Voluntary

Establish partnerships for funding and implementing wetland projects

Voluntary

Key
Strategies that address direct impacts to wetlands
Strategies that address indirect impacts to wetlands
Strategies that address both indirect and direct impacts to wetlands

Incorporate Wetland Management into Local Watershed Plans   Back to Top

Incorporating wetland protection into the local watershed planning process can help minimize impacts to wetlands and identify priority wetlands to be conserved.  During the watershed planning process, local wetlands must be inventoried, assessed, managed, and prioritized on a watershed scale rather than on a site-by-site basis.  This can be done through an initial desktop inventory of wetlands based on available mapping, followed by a detailed field assessment to verify the location of the wetland, function and condition. Selecting priority wetlands for conservation will vary for each community.  Factors to consider when choosing wetland conservation sites include: aligning functions provided by the wetland to existing community goals, location in the watershed, size and connection to landscape features, ownership and vulnerability to future development.  The wetland inventory is then used by the community to make better choices to preserve the highest quality wetlands, protect the most vulnerable wetlands, and find the best sites for wetland restoration.  By identifying the best wetland sites in advance of development, there is an increased chance of permanent protection. Additionally, the watershed plan is shared with the regulatory community as a proactive approach to inform wetland permit decisions made by state and federal agencies, to affect compensatory mitigation decisions regarding impacted wetland resources, or to identify opportunities for voluntary wetland conservation and restoration programs.

CASE STUDY: Lake County, IL Advanced Identification (ADID) Study

Located in the Chicago suburbs, Lake County, Illinois was facing development pressure and experiencing unwanted wetland loss.  In order to protect the existing wetlands in the County, a partnership with federal, state and local agencies was developed to complete an Advanced Identification (ADID) study.  The ADID study provides an inventory of high quality wetland resources in the County that were defined as wetlands that provide the following functions; habitat quality, stormwater storage, and water quality mitigation.  The data from the study provides upfront information on the location of wetlands designated for protection which allows more predictability in the wetland permitting process.  The study is used at the federal level as an advisory document during federal 404 wetland permit reviews, at the local level to inform local land use decisions, identify potential mitigation/restoration sites, and identify potential sites for acquisition.

Source: Dreher, Elston, and Schaal (1992)

Adopt a Local Wetland Protection Ordinance   Back to Top

A local wetland protection ordinance can provide more stringent protection for a greater range of wetland types than is currently being regulated by state and/or federal agencies.  Local wetland protection ordinances can restrict or require a special permit for certain activities -- such as dredging, filling, clearing, and paving -- within wetland boundaries or buffers.  Communities can either adopt a new wetland protection ordinance or revise existing ordinances such as zoning, erosion and sediment control, and stormwater management ordinances.

CASE STUDY: A Model Local Ordinance to Protect Wetland Functions

Wetlands & Watersheds Article 4 presents a model wetland drainage area protection ordinance available for use by local governments to protect wetland functions.  The model ordinance aims to protect wetlands from indirect impacts not addressed under the Section 404 permit program.  The model ordinance uses the following concepts and principles for protecting wetlands: identifying sensitive wetlands, addressing wetland contributing drainage areas, and applying wetland protection criteria.

Adopt Floodplain, Stream Buffer, or Hydric Soil Ordinance to Indirectly Protect Wetlands   Back to Top

As discussed in Update Local Wetland Maps, most communities lack a detailed inventory of their wetlands and instead rely on federally available National Wetlands Inventory maps.  These maps are outdated and thus can result in a lack of comprehensive wetland protection.  In these cases, communities may choose to protect wetlands indirectly through the protection of other natural resource features as a surrogate for wetlands such as floodplains, stream buffers, and hydric soil features.  Figure 5.1 provides an example of how to overlap GIS layers with wetlands to provide significant wetland protection.  A more detailed approach to protecting local wetlands is provided in Update Local Wetlands Maps.

 

Figure 5.1. Wetland maps showing overlap with the 100-foot stream buffer (top), 100-year floodplain (center), and hydric soils (bottom) (Graphic source: Wetlands & Watersheds Article 3)

Figure 5.1. Wetland maps showing overlap with the 100-foot stream buffer (top), 100-year floodplain (center), and hydric soils (bottom) (Graphic source: Wetlands & Watersheds Article 3)

 

Select Techniques for Conserving Wetlands   Back to Top

A Conservation plan should be developed for individual wetlands that include what land conservation tools will be used, who will apply them and when they will be applied.  Communities can choose from directly purchasing the land, working with a local land trust or other organization to acquire the land or restrict development using tools such as conservation easements.  Several tools available are described below.

  • Land acquisition – Outright acquisition of title to conservation areas by a municipality, land trust, or other nonprofit organization that provides full control of the land.
  • Conservation easement or Purchase of Development Rights (PDRs) – Conveyances of development rights necessary for protection of specific conservation values from a property’s landowner to a municipality, land trust, or other nonprofit organization.  In a PDR program, the development rights are purchased by the program.
  • Transfer of Development Rights (TDRs) – Land use planning technique that transfers development potential from environmentally sensitive areas, called sending zones, to specific areas designated for growth, called receiving zones.

CASE STUDY: Eightmile River Watershed, Connecticut

The lower Connecticut River is home to internationally recognized tidal marsh communities, exceptionally intact forest blocks and tributaries, and a multitude of creatures, including six kinds of plants and animals that are rare or endangered worldwide. The Nature Conservancy (TNC) has protected more than 4,000 acres in the Lower Connecticut River region since 1960. A key component of TNC’s Lower Connecticut River Program is community partnerships, particularly in East Haddam, Lyme and Salem, the three towns through which the Eightmile River flows. This tributary of the Connecticut has remarkably high water quality, and is surrounded by large blocks of undeveloped forest.  Despite more than 350 years of settlement, the area today is more than 80 percent forested. It comprises a variety of habitats, from its cold, fast-flowing headwaters to the freshwater tidal marshes where it meets the Connecticut.

Local government partners have been working with TNC to protect the Eightmile River watershed by acquiring key parcels of land and conservation easements. In October of 2004, the town of Lyme and TNC protected the town's highest conservation priority, the 480-acre Jewett property.  A total of 434 acres were purchased, while conservation easements protected the remaining 46 acres for a total of $3,270,500. It was one of the three largest unprotected parcels in the Eightmile River watershed, and includes more than a mile of high quality tributaries of the Connecticut River. The land links a 1,000-acre block of protected open space to the south with a 3,000-acre block to the northeast, forming more than 10 miles of open space predominantly along the Eightmile River. The cost of the acquisition was split by TNC and the town of Lyme. A portion of the town’s funding came from the state Department of Environmental Protection Open Space and Watershed Protection grant program.

Source: TNC (no date)

Require Vegetated Buffers around all Wetlands   Back to Top

Wetland buffers provide numerous benefits including wildlife habitat, removal of pollutants from runoff, reduction in erosion, temperature moderation, storage of floodwaters, increased aesthetic and recreational value, and providing a visual separation between wetlands and developed areas.  The benefits provided by the wetland buffer depend on the buffer width.  Widths of 50 -100 feet are recommended to protect wetland water quality, while widths of 100 to 300 feet or more are recommended for wetlands with important wildlife functions (EOR, 2001; Chase et al., 1997; Castelle et al., 1992).  Wetland buffer widths can be set for all wetlands, or a community may choose to set buffer widths based on wetland type or wetland functions performed.  Communities can choose to require vegetated buffers around wetlands through expanding or adding to a local wetland protection ordinance, adding wetlands to an existing stream buffer ordinance, or incorporating wetland buffers into a post-construction stormwater management ordinance.

CASE STUDY: Washington State Wetlands Rating System

Washington State Department of Ecology developed a rating system for wetlands based on functions, values, sensitivity to disturbance, rarity, and replacement difficulty.  Local management decisions that are based on this rating include: the level of impact avoidance required, width of buffers necessary to protect from adjacent development, mitigation acreage and replacement ratios, and permitted uses in wetlands. The wetlands rating system includes four categories, ranging from the highest quality, rare wetland types (Category I) to the smallest, and least diverse wetlands (Category IV).  Category I wetlands include Natural Heritage wetlands and bogs, and require a buffer width of 215 feet, while only a 50 foot buffer is required for Category IV wetlands.

Source: WADOE (1993)

Expand Wetland Buffers to Connect Wetlands with Critical Habitats   Back to Top

Communities can provide for flexible wetland buffer widths that allow linking wetlands together with high value upland habitats.  Large, unbroken habitat areas are valuable for habitat thus providing for improved habitat value and function of the wetland.  In addition, upland habitat adjacent to wetlands provide critical habitat for many semi-aquatic and terrestrial ecotone species (Semlitsch and Jensen, 2001).  Communities should be flexible in their ordinance requirements to encourage the creation of large, contiguous habitat areas and linkages between these areas.

CASE STUDY: King County, Washington Critical Areas Ordinance

King County, Washington’s Critical Areas Ordinance states that an increase in buffer width of 50 feet may be required for certain wetland types if located within 300 feet of priority habitat areas, as defined by the state.  Alternatively, the developer may provide a relatively undisturbed vegetated corridor at least 100 feet wide between wetlands and all priority habitat areas located within 300 feet of the wetland, provided this corridor is protected by easement.

Source: King County, Washington (2005)

Increase Stream Buffer Widths to Protect Downstream Wetlands   Back to Top

Wetland buffers can’t provide protection from all activities within the wetland drainage area.  To provide for extra protection, communities can increase the stream buffer width on tributaries to sensitive wetland drainage areas or on direct tributaries to sensitive wetlands.  Changes to a community’s stream buffer ordinance can be made to reflect increased buffer widths for streams that drain to sensitive wetlands.

Encourage Designs that Minimize the Number of Wetland Crossings   Back to Top

Wetland crossings by roads or utilities often result in outlet constrictions and cause hydrologic impacts to wetlands.  Communities should limit the number of wetland crossings in a new development by:

  • Using efficient road layouts
  • Focus development away from the wetlands
  • Use existing crossings
  • Use a single crossing for utilities and roads

Developers should be required to provide an inventory of natural resources before a site is developed to allow for identification of sensitive areas and the design of the site to avoid these areas at the early planning stages of site design.  In addition, the local site plan review process should coordinate with federal and state regulatory processes to determine whether wetland impacts are minimized or avoided altogether.

Encourage or Require Site Design Techniques to Protect Wetlands   Back to Top

Use of Open Space Design

Open space design is a site layout technique that achieves the conservation of natural resources on a lot by clustering the development on another portion of the lot.  This design creates less impervious cover, preserves forest and wetlands, and reduces stormwater runoff.  Communities can require open space design community-wide through their existing subdivision regulations or may require the practice within a wetland protection overlay zone, within drainage areas to sensitive wetlands, or on sites with wetlands.  A local open space design ordinance should require a percentage of existing open space be conserved for each zoning district, define allowable and restricted uses for the open space, and an enforcement mechanism.

Utilize Natural Drainage Systems

During the development process, land is cleared and graded often resulting in soil compaction and destruction of natural drainage ways.  Communities can minimize these impacts by combining the following goals into the site development regulations as shown in Figure 5.2.

  • Avoid construction activity in the most sensitive areas
  • Develop the site using the existing terrain
  • Use the natural topography and vegetated waterways to convey runoff
  • Direct runoff to pervious areas for infiltration

 

Figure 5.2. Conventional development (top) versus development that works with the existing topography (bottom) (Graphic source: MNSWAG, 1997)

CASE STUDY: The Villages of Thomas Run

When originally proposed, the Village of Thomas Run in Harford County, Maryland consisted of 450 single-family homes on individual lots. The plan required extensive filling of wetlands and five stream crossings. When the County rejected the proposal, citing adverse impacts on wetlands, the developer hired a local planning and engineering consultant to redesign the site. The revised plan called for townhomes to be clustered on upland portions of the site. Careful designing of the site allowed nearly half of the site to be preserved as open space, reduced the number of stream crossings, and greatly minimized the impact to wetlands.

Source: ULI (1994)

Require Perimeter Control Practices Along Wetland Buffer Boundaries   Back to Top

Perimeter controls at development sites are typically placed on the upland boundary of streams and wetlands during the active construction phase of a project.  These devices include sediment traps and basins, diversions/dikes, earthen berms, and silt fences.  It is recommended that perimeter controls be installed along the boundary of any required wetland buffer, rather than at the wetland boundary (Figure 5.3).  This practice allows for additional sediment filtering in the wetland buffer in case the perimeter control fails.  This requirement should be reflected in the local Erosion and Sediment Control (ESC) manuals.

Figure 5.3. Silt fence used as perimeter control to protect wetland (Photo source: MDE, no date)

Encourage more Rapid Stabilization near Wetlands   Back to Top

Immediate soil stabilization on a construction site is important to reduce sediment inputs to wetlands on exposed slopes near wetlands.  Communities should encourage developers to permanently stabilize upland areas near wetlands as soon as possible after completion of ground disturbing work and to use temporary seeding and stabilization if disturbed areas will be left exposed for longer than 14 days.  The most effective means of stabilization is to establish a vigorous grass cover to prevent erosion from occurring (Figure 5.4).  Communities should specify in their ESC program that a native wetland seed mix should be used to stabilize sites immediately adjacent to wetlands.

Figure 5.4. Exposed slope stabilized with erosion control matting

Reduce Disturbance Thresholds that Trigger ESC Plans   Back to Top

Many communities have ESC program regulations that apply to sites disturbing a minimum amount of land (e.g., Federal disturbance threshold is one acre).  Communities can reduce the sediment input to wetlands by lowering the minimum threshold that triggers ESC regulations.  In addition, communities should review the waivers and exempted projects identified in their ESC regulations.  Since ESC regulations are not required at these sites, they can cumulatively provide a large source of sediment to wetlands.  Alternatively, communities with limited resources may decide to apply tighter ESC regulations to sites within sensitive wetland drainage areas.

Increase ESC Requirements during Rainy Season   Back to Top

Construction site erosion is directly linked to rainfall events, meaning that if sites do not have ESC, sediment deposition into wetlands can increase significantly.  To reduce this occurrence, communities should require more stringent controls during the rainy season, including: restrict major grading operations, require faster vegetative stabilization, and increase the frequency of inspections.  In addition, sites should be inspected to ensure stability before the rainy season and after every storm event.

CASE STUDY: King County, Washington Erosion Control Guidance

The King County Department of Development and Environmental Services (DDES) has written guidance for contractors regarding construction site controls needed during the “wet” season of October 1 through April 30. In certain designated areas of the county, no clearing and grading work can occur during the wet season unless the site infiltrates 100% of its runoff or the applicant submits and obtains approval for a “Winterization Plan” from DDES. This plan must identify the areas where work is to be performed, describe the techniques that will be used to mitigate erosion, and include the name and number of a 24-hour contact who has demonstrated ability in erosion control.

Source:  King County, Washington Erosion and Sediment Control for Construction Sites

Encourage the Use of Site Fingerprinting or Construction Phasing   Back to Top

The best way to reduce sediment inputs to wetlands is to prevent erosion from occurring at the construction site in the first place.  Communities can prevent erosion by limiting the amount of clearing conducted at a site by encouraging site fingerprinting and construction phasing.  Site fingerprinting (also known as site footprinting) minimizes clearing at a site by limiting disturbance to the necessary minimum to construct buildings and roadways.  The limits of disturbance need to be clearly marked in the field and on the site plan.  Construction site phasing is a process of disturbing land on a site in distinct phases.  This is in contrast to the traditional construction sequencing where the entire site is cleared and graded at one time.  Under construction site phasing, a portion of the site is cleared and graded, infrastructure is installed, and the disturbed soil is stabilized before work begins on the next phase.  Since the amount of soil exposure is limited, this is a preventative approach to ESC. 

CASE STUDY: Mecklenburg County, North Carolina ESC Ordinance

Mecklenburg County, North Carolina has incorporated construction site phasing into its erosion and sediment control ordinance. The County encourages contractors not to disturb more than 20 acres at any one time. When an area larger than 20 acres is disturbed, the corresponding ESC plan must contain five additional measures to ensure that soils are exposed for the shortest amount of time possible. Included among these measures is construction sequencing and construction phasing to “justify the time and amount of exposure.”

Source: Mecklenburg County, North Carolina (2002)

Increase Frequency of Site Inspections   Back to Top

An important part of any ESC program is frequent inspections and enforcement.  Surveys reveal that 16% to 50% of ESC practices specified in plans are never installed or are installed improperly (Paterson, 1994; Mitchell, 1993).  These findings highlight the importance of bi-weekly inspections and/or inspections after certain sized storms.  Communities can require more frequent ESC inspections within the drainage areas of sensitive wetlands.  In order to avoid overburdening local ESC inspectors, communities can require contractors to hire an independent, certified erosion and sediment inspector to ensure proper installation and performance of ESC practices.

Prohibit Use of Natural Wetlands for Stormwater Treatment   Back to Top

Allowing natural wetlands to treat stormwater runoff increases the depth of temporary or permanent ponding in a wetland.  Over time, the altered hydrology transforms a natural wetland into a stormwater wetland with the loss of biological diversity and functional value.  To prevent this from occurring, communities should review their existing stormwater ordinances to makes sure they prohibit the use of natural wetlands for stormwater treatment.

Restrict Discharges of Untreated Stormwater to Natural Wetlands   Back to Top

Since wetlands are located at the low point in the landscape, stormwater outfalls may unintentionally be discharged to natural wetlands.  To prevent this from occurring, communities can require treatment of stormwater from new and existing stormwater pipe outfalls that discharge directly to wetlands through a local stormwater ordinance.  This allows removal of pollutants, such as sediment and nutrients, and dissipates the velocity of runoff into the wetland.  In addition, communities may want to consider retrofitting existing stormwater outfalls that discharge to wetlands with some form of stormwater treatment.

Discourage Installation of Stormwater Treatment Practices within Wetland Boundaries   Back to Top

Wetland buffers are intended to connect the wetland with upland habitat areas and provide a transitional area of native vegetation that protects it from future disturbance or encroachment.  As a general rule, communities should strongly discourage the location of large stormwater treatment practices, such as stormwater ponds or created wetlands, inside the wetland buffer.  In some cases, the use of a filter strip may be desirable in the wetland buffer.  This approach works well when the stormwater occurs as sheet flow or shallow concentrated flow.  When the stormwater becomes more concentrated, a stormwater depression or bioretention area may need to be used at the buffer boundary to store and release the increased runoff volumes.

Discourage Constrictions at Wetland Outlets   Back to Top

Constrictions built below wetland outlets increase stormwater runoff to natural wetlands.  Constrictions may be caused by downstream culverts, bridges, dikes, roadway embankments, stormwater embankments and other water control structures.  Each type of constriction has the potential to back water up into the wetland – increasing ponding or the frequency of inundation.  These hydrological alterations have strong influence on the wetland plant community, and can cause dieback for some woody species, and may impact other wetland dependant species.  In order to avoid these impacts, communities should carefully evaluate the effect of any proposed constriction in or near a wetland, either as part of the preliminary site plan review process or as part of the local wetland permit review.

Encourage Progressive Stormwater Management Techniques   Back to Top

In situations where development is located near wetlands, communities should use progressive stormwater management techniques to prevent a direct discharge or fill into the wetland.  These techniques use a combination of site design, source control, and stormwater treatment approaches (Hirschman and Kosco, 2008):

  1. Reduce runoff through design – use site planning and design techniques to reduce impervious cover, disturbed soils and stormwater impacts.
  2. Reduce pollutants carried by runoff – use source control and pollution prevention practices to reduce the exposure of pollutants to rainfall and runoff.
  3. Capture and treat runoff – design stormwater practices to collect and treat the stormwater that is generated after applying the first 2 steps.  This is accomplished through the use of small-scale, distributed practices close to the source of runoff (e.g. rain gardens and pervious parking) combined with conventional practices (ponds and filters).

Additional information is found in (Hirschman and Kosco, 2008) and Wetlands & Watersheds Article 4.

Develop Special Sizing Criteria for Stormwater Treatment Practices   Back to Top

Local or state stormwater manuals or regulations outline the amount of stormwater runoff that needs to be managed for storm events of various sizes.  These sizing criteria may involve recharge, water quality, channel protection, overbank flooding, and extreme flood control.  Communities may adjust their existing stormwater sizing criteria to protect wetlands from the indirect impacts of stormwater runoff.  They can also require additional information including a field investigation of any wetlands present at a development site to determine their sensitivity, delineate the drainage area to the wetland, and evaluate whether any additional runoff will be delivered to the wetland as a result of the proposed project.

This information can be used to determine special sizing criteria to protect sensitive wetlands.  Components of special sizing criteria include the recharge volume, water quality volume, channel protection volume and hydroperiod standards.  These special stormwater criteria are outlined in a model wetland ordinance that can be adopted by local communities. 

Recharge volume criteria are designed to maintain existing groundwater recharge rates at development sites in order to preserve existing water table elevations and maintain wetland hydrology.  Since many sensitive wetlands depend on groundwater to maintain their natural hydrology, communities may choose to require recharge to maintain predevelopment recharge rates within sensitive wetland drainage areas.

The water quality volume captures and treats runoff from about 90% of the rain events each year into a stormwater treatment practice.  Communities should ensure that the water quality volume is fully treated before any stormwater is discharged to a down-gradient wetland.  For sensitive wetlands such as bogs or calcareous fens, a higher level of stormwater treatment may be required.

The channel protection criteria is designed to prevent stream channel enlargement and stream habitat degradation due to the increased frequency of bankfull and sub-bankfull flows that follow urbanization (Schueler and Brown, 2004).  Channel protection can be applied to protect wetlands where future development faces a headwater stream that leads directly to a wetland and where a large proportion of freshwater wetlands are located in or near headwater stream channels that are expected to be impacted by increased stormwater discharges.

Wetland hydroperiod refers to the extended duration of inundation and/or saturation of wetland systems.  Small changes in wetland hydroperiod can have negative effects in sensitive wetlands.  Communities can adopt hydroperiod standards into their existing stormwater management regulations in order to maintain the existing wetland hydroperiod in all sensitive wetlands.

CASE STUDY: Puget Sound Wetland Guidelines

Washington State Department of Ecology’s Storm Water Management Manual specifies that discharges to wetlands must maintain the hydrologic conditions, hydrophytic vegetation, and substrate characteristics necessary to support existing and designated beneficial uses. To provide guidance for developers on how to meet this requirement, the Puget Sound Wetlands and Stormwater Management Research Program developed criteria for determining the maximum allowed exceedances in alterations to wetland hydroperiods. The resulting Puget Sound Wetland Guidelines are summarized below.

In order to determine if the proposed development will impact the wetland hydroperiod, designers must first determine the existing hydroperiod of the wetland using simulation models or actual measurement over a period of time. Next, they must forecast the future hydroperiod of the wetland using simulation models or impervious cover (IC) estimates and relationships between IC and water level fluctuations (WLF) (Chin, 1996; Horner et al., 1997). The future hydroperiod of the wetland must meet the following standards:

  • Mean annual WLF shall not exceed 20 cm
  • The frequency of stage excursions of 15 cm above or below pre-development stage shall not exceed an annual average of six
  • The duration of such stage excursions shall not exceed 72 hours per excursion
  • The total dry period shall not increase or decrease by more than two weeks in any year 
  • Alterations to watershed and wetland hydrology that may cause perennial wetlands to become vernal shall be avoided

For priority peat wetlands (e.g., bogs, fens), the duration of stage excursions above the pre-development stage shall not exceed 24 hours in any year. For wetlands inhabited by breeding native amphibians during breeding season, the magnitude of stage excursions above or below the pre-development stage shall not exceed 8 cm, and the total duration of such excursions shall not exceed 24 hours in any 30-day period.

If the analysis forecasts exceedance of any of the hydroperiod standards, then the designer must consider reducing the level of development, increasing the runoff storage capacity, using selective runoff bypass, or increasing runoff infiltration, where feasible. After development, wetland hydroperiod must be monitored continuously to determine if applicable limits are exceeded.

Source: Horner et al. (1997)

Promote Effective Stormwater Treatment Practices to Protect Downstream Wetlands   Back to Top

The selection and design of stormwater treatment practices applied in the wetland drainage area is very important in protecting sensitive wetlands.  Within wetland drainage areas, communities can review their stormwater design manuals to provide more guidance on the use of infiltration and filtering practices as well as encourage the following Better Site Design techniques:

  • Disconnection of rooftops and other impervious surfaces from the stormdrain network
  • Use of pervious areas to treat runoff close to the source through recharge and infiltration
  • Use of swales rather than curb and gutters along streets wherever possible
  • Conserve forests and other natural areas at the site to maintain predevelopment hydrology
  • Replant open or turf areas to achieve greater site forest cover or other native vegetative cover
  • Take care during clearing and construction to minimize the degree of soil compaction

For additional information on the use of specific stormwater treatment practices to protect wetlands refer to Wetlands & Watersheds Article 3 and Hirschman and Kosco (2008).

Conduct Illicit Discharge Surveys for all Outfalls to Wetlands   Back to Top

A storm drain that has measurable flow during dry weather containing pollutants is defined as an “illicit discharge.”  Sources of illicit discharges include cross-connections between the sewer system and the storm drain system, as well as land use activities that illegally discharge pollutants to the storm drain system.  Storm drain outfalls can contribute a variety of pollutants to a wetland during both dry and wet weather.  A discussion of the impact of urban stormwater pollutants to wetlands is provided in Wetlands and Watersheds Article 1. To help protect wetlands from illicit discharges, communities can conduct illicit discharge surveys for all outfalls that discharge directly to wetlands or are located within wetland drainage areas. Brown et al. (2004) provides guidance on conducing illicit discharge surveys.

Actively Enforce Restrictions on Dumping in Wetlands and their Buffers   Back to Top

Illegal dumping is a problem in urban stream valleys and wetlands because these areas do not have obvious landowners, are not usually policed, and are often poorly lit (Figure 5.5).  Even though most communities have ordinances that prohibit dumping, they are difficult to enforce.  To combat this problem, communities should specifically identify wetlands and buffers as restricted dumping areas, post No Dumping signs, and make use of community groups or adopt-a-wetland groups as monitors, and clearly define enforcement penalties.

Figure 5.5. Illegal dumping in a wetland (Photo source: USFWS, no date) 

 Require Enhanced Nutrient Removal from On-site Waste Water Treatment Systems   Back to Top

On-site waste water treatment systems provide a means of treating household waste for those areas that do not have access to public sewer, or where sewer systems are not feasible.  Traditional on-site waste water treatment systems are not designed to remove nitrogen from the waste water they discharge.  Nitrogen from these systems leaches into groundwater, which can have major water quality implications for wetlands dependant on groundwater.  To protect wetlands from these impacts, communities can require enhanced nutrient removal from these systems.  Communities can define the desired removal efficiencies for these practices or in some cases it is driven by state regulations.  Communities can encourage the use of enhanced nutrient removal systems by establishing more stringent performance criteria for waste water treatment, including higher nutrient removal efficiencies, and writing this into their local septic system design guidance and/or ordinances.

Require Regular Septic System Inspections   Back to Top

One of the biggest factors for septic system failure is lack of maintenance.  Septic system failure has a huge impact on wetland water quality by releasing bacteria and other pollutants into groundwater.  To combat this problem, local health departments must regularly inspect septic systems and take actions to fix or replace failing systems.  Innovative approaches to local septic system management include charging homeowners a monthly fee that is used for inspection, maintenance, and education.  Other communities have developed a revolving loan program to provide low-cost repair to failed systems.

CASE STUDY: Nags Head North Carolina Septic Health Initiative

The Town of Nags Head began a Septic Health Initiative in late 2000 designed to develop strategies and programs to improve the performance of septic systems in the Town. The programs developed were based on the work of the Town of Nags Head Septic Health Committee. This committee is composed of a cross-section of Town citizens sharing a deep concern for the protection of water quality within and around the Town. The goals of the Septic Health Committee in developing the Initiative were to improve septic systems performance while maintaining acceptable surface and ground water quality, as well as controlling the density of developed land by promoting the use of on-site waste systems. The Septic Health Committee developed a series of four programs designed to improve the performance of septic systems while gathering information about septic systems in the town. The four programs are:

  • Septic Tank Pumping and Inspection Program 
  • Water Quality Monitoring Program
  • Education Program
  • Decentralized Wastewater Management Plan

Click here for additional information.

Incorporate Wetlands into Watershed Education Programs   Back to Top

The general public is unaware of the benefits that wetlands provide and may have misconceptions about wetlands, including the idea that wetlands function only as breeding grounds for mosquitoes that carry the West Nile Virus.  Communities have the challenge of educating the public to overcome these barriers and provide information on the benefits of wetlands. Key information that should be included in a wetland education program includes providing information on how the average citizen can reduce inputs of nutrients and other pollutants to wetlands, enhance or restore wetlands on their property, and provide input on the federal wetland permitting process and state or local programs, where applicable.  Examples of wetland education resources include:

Post Signs to Identify Wetlands, Buffers, and Wetland Drainage Area Boundaries   Back to Top

An important companion to any new local ordinance or wetland protection program is a means of notifying the public of wetland values and/or new requirements.  Signs are most commonly used to notify the public about ordinances that protect natural resources, such as wetlands and their buffers.  Signs are posted to identify the boundaries of the protected area, to inform residents of restricted uses and penalties, and to educate residents as to why these areas are protected.  Communities should post signs around protected wetlands and their buffers, and may even be used to identify the boundaries of sensitive wetland drainage areas (Figure 5.6).

Figure 5.6. Sign posted at conserved wetland (Photo source: www.landandfarm.com)

Manage Invasive Wetland Plants   Back to Top

In disturbed wetland ecosystems invasive plants may become dominant because they are tolerant of changes in hydrology and pollutant inputs.  Common invasive plant species include purple loosestrife, phragmites, reed canary grass, cattails, kudzu, multiflora rose, Asiatic tearthumb, water hyacinth, and Eurasian watermilfoil.  Invasive plant control methods vary with each species and can range from simple measures, such as mowing, to methods that require heavy equipment, herbicides, or burning.  Most methods require repeat application and constant monitoring, and will never fully eradicate the species from a site.  Therefore, communities should focus on the prevention of invasive species.  Invasive plant removal can be prioritized in sensitive wetlands and include control of invasive plants with wetland restoration projects. Several resources for wetland invasive plant management are listed below.

Establish Volunteer Wetland Monitoring and Adoption Programs   Back to Top

Communities can establish programs that engage citizen volunteers to monitor and ‘adopt’ wetlands in the watershed.  Adopt-a-wetland programs are similar in concept to the successful adopt-a-highway program – volunteers adopt a specific wetland and can perform a range of general maintenance such as trash removal, invasive species removal, and buffer plantings.  These types of programs provide educational and research opportunities for residents and can lead to increased concern, understanding, and stewardship or wetlands.  Another way to engage the community is through a wetland monitoring program that can range from simple, qualitative assessments to more advanced monitoring including surveys of invasive species, water quality, amphibians, and benthic macroinvertebrates.  Volunteers can range from school children to scout groups to senior citizen groups.

CASE STUDY: Oakdale, Minnesota Adopt-A-Wetland Program

The City of Oakdale, Minnesotaestablished an adopt-a-wetland program for community groups, homeowner associations, businesses, or other interested parties who want to help with the improvement and upkeep of a particular Oakdale wetland, pond, lake or stream. Volunteers can select their own water body or have the City suggest one for them, and choose from the following list of activities:

  • Trash removal
  • Invasive plant removal (e.g., buckthorn, purple loosestrife)
  • Native buffer planting
  • Water quality monitoring
  • Wetland data collection
  • Wetland monitoring
  • Community education

Volunteers can conduct the activity as frequently as they wish, and have officially ‘adopted’ the wetland after having completed one activity. Volunteers receive an Adopt-A-Wetland certificate, and a sign commemorating the volunteer group may be installed at the site.  The City has created an Adopt-A-Wetland How-To Kit, which contains instructional materials and resources for adopting a wetland.  This kit is available on the City’s website.

Source: City of Oakdale, Minnesota (no date)

Encourage Wetland Landowner Stewardship   Back to Top

There are several federal funded programs through the USDA to implement wetland conservation and restoration techniques on agricultural lands.  These programs range from cost-sharing assistance to landowners for developing habitat for threatened and endangered species, and other wildlife to establishing and maintaining long-term conservation practices such as buffer plantings and cattle fencing (Figure 5.7).  The USDA Natural Resources Conservation Service (NRCS) provides more information on federal programs for wetland stewardship.  Communities can provide additional funding for projects on non-agricultural lands to encourage wetland landowners to establish buffers, monitor wetlands, or conduct restoration activities.  Financial incentives can include financial assistance, such as estate or personal property tax credits, recognition by local government, and on-site technical assistance.

Figure 5.7. Before cattle fencing project (top) and after (bottom). (Photo Source: USFWS, no date).

 

Establish Partnerships for Funding and Implementing Wetland Projects   Back to Top

Communities should work with local land conservation and other non-profit groups to help implement wetland conservation and restoration projects recommended as part of a watershed plan.  These groups can provide volunteers to monitor or maintain project sites or implement simple projects, such as wetland buffer plantings.  Other groups, such as land trusts, can hold conservation easements or raise funds to acquire priority conservation lands.  A list of example potential partners can be found in Wetlands & Watersheds Article 3.

CASE STUDY: Wetland Restoration in the San Francisco Bay Estuary

The San Francisco Bay Estuary is the Nation's second largest and perhaps the most biologically significant estuary on the Pacific Coast. It has also suffered the most extensive degradation of any estuary in the nation. Many years of filling, pollution, and alien species invasions have taken a great toll on the ecosystem. Despite these losses, however, the San Francisco Bay Estuary is now a major center for a vibrant habitat restoration movement.

The Bay Estuary's ecological value lies mainly in the wetlands along its edge, and in the riparian habitats of streams and rivers feeding into it. These habitats are essential to the health of the myriad fish and wildlife populations of the region. Millions of shorebirds and waterfowl stop by during their annual migrations between Alaska and South America. The Western Hemisphere Shorebird Reserve Network has designated the San Francisco Bay Estuary as a site of "Hemispheric Importance" (its highest ranking), and the North American Waterfowl Management Plan has listed it as one of 34 waterfowl habitats of major concern in North America.

Over the past two decades, the San Francisco Bay Joint Venture (SFBJV) has made significant progress to protect what remains and to begin restoring as much as possible of what was lost. This partnership of public agencies, environmental organizations, the business community, local governments, the agricultural community, and landowners works cooperatively to protect, restore, increase, and enhance wetlands and riparian habitat in the San Francisco Bay watershed.

The SFBJV helps partners put habitat restoration, acquisition and enhancement projects on the ground by connecting partners with the funding opportunities, information and resources they need to make projects happen. Over the past few years, the San Francisco Bay Joint Venture (SFBJV) partners have completed 22 wetland protection, restoration, or enhancement projects involving over 11,100 acres, with another 31,400 acres in progress. Working with the SFBJV, Ducks Unlimited staff has created a comprehensive, yet user-friendly habitat project tracking system that will help the SFBJV with their facilitation role and help the partnership track regional progress towards their restoration goals.

Source: http://www.sfbayjv.org/

 

Resources for Protecting Wetlands Locally

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Digitize
The process of converting features on a paper map into digital format using a trace methodology, which results in the creation of a spatial dataset.
Ecotone

A transition area between two adjacent, but different plant communities.

Indirect Wetland Impacts
Impact to wetlands caused by inputs of stormwater and pollutants generated by land development or other activities within the wetland CDA.
Direct Wetland Impacts
Wetland loss or degradation resulting from activities that occur within wetlands, such as dredging, filling and draining.  Activities that cause direct impacts are largely regulated through the federal and state wetland permitting process.
Stormwater Treatment Practices

A structural or non-structural practice designed to temporarily store or treat stormwater runoff in order to mitigate flooding, reduce pollution, and provide other amenities (also called a Best Management Practice – BMP).

Hydrogeomorphic
Factors that influence how wetlands function, including geomorphic setting, water source, and hydrodynamics.
Hydrogeomorphic
Factors that influence how wetlands function, including geomorphic setting, water source, and hydrodynamics.
Sinks
A cell or set of spatially connected cells that cannot be assigned flow direction in a raster elevation dataset. This can occur when all neighboring cells are higher than the processing cell or when two cells flow into one another. Sinks can indicate areas where water is likely to pond, but can also be an error in the dataset.
Facultative Wetland Plants
Species that usually occur in wetlands (approximately 67% - 99% probability), but also occur in non-wetland areas (approximately 1% - 33% probability).
Obligate Wetland Plants
Species that occur almost always in wetlands under natural conditions (greater than 99% probability), but which may also occur rarely in non-wetlands (less than 1% probability).
Interferometric Synthetic Aperture Radar (IFSAR)
A radar technique that uses two or more synthetic aperture radar (SAR) images to generate surface elevation using differences in the phase of waves returning to the satellite or aircraft.
Interferometric Synthetic Aperture Radar (IFSAR)
A radar technique that uses two or more synthetic aperture radar (SAR) images to generate surface elevation using differences in the phase of waves returning to the satellite or aircraft.
Light Detection and Ranging (LiDAR)

A remote sensing technique that measures properties of pulsed laser light reflected from objects to determine their position, velocity, and other information.

Light Detection and Ranging (LiDAR)

A remote sensing technique that measures properties of pulsed laser light reflected from objects to determine their position, velocity, and other information.

Light Detection and Ranging (LiDAR)

A remote sensing technique that measures properties of pulsed laser light reflected from objects to determine their position, velocity, and other information.

Digital Elevation Model (DEM)
A digital file consisting of terrain elevations for ground positions at regularly spaced horizontal intervals.
Digital Elevation Model (DEM)
A digital file consisting of terrain elevations for ground positions at regularly spaced horizontal intervals.
Hyperspectral Data

Information collected and processed from across the electromagnetic spectrum. Spectral signatures (unique “fingerprint” left by specific objects) enable identification of materials that make up a scanned object.

Remote Sensing
Gathering and recording information about objects without actual contact through the use of such techniques as photography, infra-red imagery, and radar.
Hydrophytes
A plant that grows wholly or partially submerged in water.
Blackspots
Areas on aerial photos that show up as dark blue, dark grey, or black and are indicative of saturated soil conditions.
Stereoscopic
The ability to see three dimensionally by using two views of a single object from slightly different positions typically through the use of an optical aid known as a stereoscope.
Hydric Soils
Soils that are saturated, flooded, or ponded for a long enough period during the growing season to develop anaerobic conditions in the upper soil horizons.
Hydric Soils
Soils that are saturated, flooded, or ponded for a long enough period during the growing season to develop anaerobic conditions in the upper soil horizons.
Hydric Soils
Soils that are saturated, flooded, or ponded for a long enough period during the growing season to develop anaerobic conditions in the upper soil horizons.
Hydric Soils
Soils that are saturated, flooded, or ponded for a long enough period during the growing season to develop anaerobic conditions in the upper soil horizons.
Hydric Soils
Soils that are saturated, flooded, or ponded for a long enough period during the growing season to develop anaerobic conditions in the upper soil horizons.
Hydric Soils
Soils that are saturated, flooded, or ponded for a long enough period during the growing season to develop anaerobic conditions in the upper soil horizons.
Hydric Soils
Soils that are saturated, flooded, or ponded for a long enough period during the growing season to develop anaerobic conditions in the upper soil horizons.
Hydric Soils
Soils that are saturated, flooded, or ponded for a long enough period during the growing season to develop anaerobic conditions in the upper soil horizons.
Geographic Information Systems (GIS)

A system that integrates hardware, software, and data for capturing, managing, analyzing, and displaying all forms of geographically referenced information.

Geographic Information Systems (GIS)

A system that integrates hardware, software, and data for capturing, managing, analyzing, and displaying all forms of geographically referenced information.

Digitize
The process of converting features on a paper map into digital format using a trace methodology, which results in the creation of a spatial dataset.
Minimum Mapping Unit

The minimum size or dimensions for features to be mapped as lines or areas for a given map scale.