1987 Corps of Engineers Wetland Manual

The 1987 Corps of Engineers Wetland Delineation Manual is the official technical standard used by the U.S. Army Corps of Engineers for identifying and delineating wetlands in accordance with the Clean Water Act. This comprehensive manual provides detailed guidance on wetland identification, classification, and boundary determination using the three-parameter approach: hydrology, hydric soils, and hydrophytic vegetation.

Introduction and Purpose

The 1987 manual establishes standardized methods for wetland delineation to ensure consistent application of Section 404 of the Clean Water Act across all Corps districts.

Wetland Definition and Criteria

Wetlands are defined as areas that are inundated or saturated by surface or groundwater at a frequency and duration sufficient to support hydrophytic vegetation.

1. Primary Indicators: Hydrology, soils, and vegetation must be present
2. Supporting Evidence: Secondary indicators for borderline cases
3. Exclusions: Areas that do not meet all three criteria
4. Transition Zones: Areas with mixed characteristics

IMPORTANT! All three parameters must be evaluated for proper wetland identification.

Three-Parameter Approach

The manual employs a three-parameter approach requiring positive indicators in hydrology, soils, and vegetation.

1. Hydrology: Evidence of saturation or inundation
2. Hydric Soils: Soil characteristics indicating anaerobic conditions
3. Hydrophytic Vegetation: Plant species adapted to wet conditions
4. Parameter Integration: How indicators work together

NOTE: Positive indicators in all three parameters are required for wetland designation.

Hydrology Indicators

• Primary Indicators: Surface water, soil saturation, water marks
• Secondary Indicators: Drainage patterns, sediment deposits
• Seasonal Variations: Accounting for temporal hydrology
• Measurement Methods: Field observation and monitoring
• Documentation: Recording hydrologic evidence

Hydric Soils Identification

Hydric soils show evidence of anaerobic conditions through color, texture, and chemical properties.

Key Characteristics: Gleying, mottling, organic accumulation, redoximorphic features.

Soil Types: Mineral hydric soils, organic soils (peat, muck), problematic hydric soils. Field Tests: Chroma determination, redox potential, soil color charts. Documentation: Soil profiles, sampling procedures, classification.

Hydrophytic Vegetation

Plant species adapted to living in saturated soil conditions with limited oxygen availability.

1. Indicator Species: Obligate wetland plants (OBL)
2. Facultative Species: Facultative wetland (FACW) and facultative (FAC)
3. Vegetation Analysis: Dominance testing and prevalence index
4. Regional Variations: Plant lists by geographic region

Tip: Use regional wetland plant lists for accurate identification.

Delineation Procedures

Step-by-step methodology for determining wetland boundaries in the field.

1. Site Preparation: Review maps and aerial photos
2. Field Reconnaissance: Initial site assessment
3. Transect Establishment: Systematic sampling lines
4. Data Collection: Recording all three parameters
5. Boundary Determination: Identifying wetland-upland interface
6. Flagging and Mapping: Marking delineated boundaries
7. Quality Control: Verification and documentation

WARNING! Proper training required for accurate delineation.

Data Collection Methods

Standardized procedures for collecting and recording wetland parameter data.

Problematic Wetland Situations

Guidance for difficult delineation scenarios including agricultural areas, disturbed sites, and seasonal variations.

CAUTION! Professional judgment required for atypical wetland situations.

Regulatory Framework

The manual operates within the context of Section 404 of the Clean Water Act and Corps regulatory authority over waters of the United States.

Field Applications

Training: Required for all Corps personnel conducting delineations.

Updates: Supplemental guidance memos and regional supplements available.