Wetland Assessment Methods

FHWA Needs

Laws and Regulations

• National Environmental Policy Act

• Section 404 CWA Regulatory Program

• Executive Order 11990, Protection of Wetlands– Isolated wetlands under EO 11990

FHWA Regulation

• 23 CFR 777, Mitigation of Impacts to Wetlands– Requires consideration of wetland functions

and values to be impacted or replaced– Determination of landscape level functions and

significance of impacted wetlands and mitigation needs

– Consider both the short and long term effects of the project

Other Guidance

• FWHA Policy of a net gain of wetlands– 1.5:1 compensation ratio

• Section 404 Mitigation Action Plan– Emphasizes landscape level

functions– Functional replacement– Best available science

• Corps REGL 2-02– Watershed approach– Assessment of Streams

Challenges for Linear Highway Projects

• Impacts could occur in different drainage areas

• Wetlands within and among drainages could be of various types

• Wetlands in different areas may perform different functions

FHWA Assessment Needs and Objectives

• Methodology that is broader in scope to account for different wetland types and functions

• Flexible – Utilize 1 assessment methodology for one project that takes into account different wetland sizes, functions, and types.

Large projects on New Alignment, such as Legacy Parkway – over 100 acres impacts

Small projects – widening, realignments, safety – often less than acre of impact

FHWA/DOT Needs in Assessment

• Standardized – One methodology per region or statewide uniformity

• Rapid – Able to accommodate project timelines• Functionally based – Since linear projects may

impact several different types of wetlands, a functionally based assessment is necessary.

• Quantitative – determine appropriate mitigation ratios and identify suitable mitigation sites by site characteristics – NEPA, 404, 11990

• Efficient in use of personnel time

FHWA/DOT Needs• Identify all information needs for

regulatory permitting requirements within the method’s basic framework– Multi stage for different project scopes – Expandable for large projects

Assessment Objectives

• Allowances for integration of ecosystem based mitigation including wildlife habitat, vegetated buffers, uplands, and open water habitat

• Applicable to Banking Preference – Recognize appropriate applications of bank in mitigation

• Recognize that on-site mitigation is not feasible in all instances

• Monitoring – recognize important indicators– Determine success in mitigation – specific functional

indicators or condition indices

Alternatives in Assessment

• Hydrogeomorphic Approach (COE)– Has withstood legal challenge (on Legacy

Parkway Project – over 100 acres of impacts)– Quantitative when correctly developed and

applied – provides a numerical output– Establishes appropriate mitigation ratios– Identifies critical site parameters– Can address all functions, including wildlife– Updatable

HGM Downside

• Long development time before application

• Can be relatively time consuming when applied to smaller projects

• Needs special development to assess landscape level functions – such as wildlife

• Does not differentiate wetland types well – weak alternatives analysis

Alternatives In Assessment

• New England Methodology (CORPS NED)– Relatively quick– Addresses all functions– Does not provide numerical output– Does not help define mitigation ratios– Is not expandable for larger projects

• Requires special studies that are not defined in the method to be developed for larger projects

– Does not address landscape relationships

Assessment alternatives

• Montana DOT Methodology– Combines quantitative and subjective approaches

to give subjective assessment of wetland condition, function and value

– Recognizes specific wetlands functions– Yields wetland value ranking

Alternatives in assessment

• Washington DOT methodology– Uses HGM like characteristics to define

wetland functions– Can associate landscape level functions– Helps identify specific mitigation site

characteristics– Adaptation of New England methodology

FHWA Hopes For

• Continued development of a functional based approach that will– Be flexible for smaller projects– Expandable for large projects– Identify all permit needs– Operate in accordance with the regulations– Regionally standardized– Help establish appropriate mitigation ratios