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Conservation practice standards are reviewed periodically and updated if needed. To obtain 

the current version of this standard, contact your Natural Resources Conservation Service 

State Office or visit the Field Office Technical Guide.

NATURAL RESOURCES CONSERVATION SERVICE

CONSERVATION PRACTICE STANDARD

WETLAND ENHANCEMENT

(Ac.)

CODE 659

DEFINITION

The augmentation of wetland functions beyond 

the original natural conditions on a former, 

degraded, or naturally functioning wetland site; 

sometimes at the expense of other functions.

PURPOSE

To increase the capacity of specific wetland 

functions (such as habitat for targeted 

species, and recreational and educational 

opportunities) by enhancing:

• Hydric soil functions (changing soil 

hydrodynamic and/or bio-geochemical 

properties).

• Hydrology (dominant water source, 

hydroperiod, and hydrodynamics).

• Vegetation (including the removal of 

undesired species, and/or seeding or 

planting of desired species).

• Enhancing plant and animal habitats.

CONDITIONS WHERE PRACTICE APPLIES

This practice applies to any degraded or nondegraded wetland sites with hydric soils, 

where the objective is to enhance selected 

wetland functions to conditions different than 

those that originally existed on the site.

This practice does not apply to:

• The treatment of point and non-point 

sources of water pollution (Constructed 

Wetland – Code 656); 

• The rehabilitation of a degraded wetland or 

the reestablishment of a former wetland so 

that soils, hydrology, vegetative 

community, and habitat are a close 

approximation of the original natural 

condition and boundary that existed prior 

to the modification (Wetland Restoration –

Code 657).

• The creation of a wetland on a site location 

that was historically non-wetland. 

(Wetland Creation – Code 658).

• The management of fish and wildlife 

habitat on wetlands enhanced under this 

standard.

CRITERIA

General Criteria Applicable to All Purposes

The purpose, goals, and objectives of the 

enhancement shall be clearly defined in the 

enhancement plan, including soils, hydrology, 

vegetation, and fish and wildlife habitat criteria 

that are to be met and are appropriate for the 

site and the project objectives. 

The planning process will evaluate the impact 

of this practice on existing non-degraded 

wetland functions and/or values. The relative 

increase or decrease in functions will be 

assessed with the use of a functional 

assessment procedure or state approved 

equivalent. The functions to be increased or 

decreased on wetlands found to be currently 

functioning at or near a “reference” condition 

will be documented.

The soils, hydrology, and vegetative conditions 

existing on the site, the adjacent landscape,

and the contributing watershed shall be 

documented in the planning process. 

The nutrient and pesticide tolerance of the 

plant and animal species likely to occur shall 

be evaluated where known nutrient and 

pesticide contamination exists. Sites 

suspected of containing hazardous material

shall be tested to identify appropriate remedial 

measures. If remedial measures are not 

possible or practicable, the practice shall not 
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be planned.

The availability of sufficient water rights should 

be reviewed prior to enhancement.

Upon completion, the site shall meet the 

appropriate wetland criteria and provide 

wetland functions as defined in the project’s 

objectives.

Invasive species, federal/state listed noxious 

plant species, and nuisance species (e.g., 

those whose presence or overpopulation 

jeopardize the practice) shall be controlled on 

the site as necessary to enhance wetland 

functions. The establishment and/or use of 

non-native plant species shall be discouraged. 

Criteria for Hydric Soil Enhancement

Enhancement sites will be located on soils that 

are hydric. 

Changes to soil hydrodynamic and biogeochemical properties such as permeability, 

porosity, pH, or soil organic carbon levels shall 

be made as needed to meet the planned 

objectives.

Criteria for Hydrology Enhancement

The hydroperiod, hydrodynamics, and 

dominant water source of the enhanced site 

shall meet the project objectives. The 

enhancement plan shall document the 

adequacy of available water sources based on 

groundwater investigation, stream gage data, 

water budgeting, or other appropriate means.

The work associated with the wetland shall not 

adversely affect adjacent properties or other 

water users unless agreed to by signed written 

letter, easement or permit.

Timing and level setting of water control 

structures required for the establishment and 

maintenance of vegetation, soil, and wildlife 

and fish habitat functions shall be determined.

Other structural practices, macrotopography 

and/or microtopography may be used to meet 

the planned objectives.

Macrotopographic features, including ditch 

plugs installed in lieu of re-filling surface 

drainage ditches, shall meet the requirements 

of other practice standards to which they may 

apply due to purpose, size, water storage 

capacity, hazard class, or other parameters. If 

no other practice standard applies, they shall 

meet the requirements for Dike – Code 356 

unless there is no potential for damage to the 

feature or other areas on or off site due to 

erosion, breaching, or overtopping.

Water control structures that may impede the 

movement of target aquatic species or species 

of concern shall meet the criteria in Fish 

Passage – Code 396.

Criteria for Vegetative Enhancement

Hydrophytic vegetation restoration shall be of 

species typical for the wetland type(s) being 

established and the varying hydrologic regimes 

and soil types within the wetland. Preference 

shall be given to native wetland plants with 

localized genetic material. 

Where natural colonization of acceptable

species can realistically be expected to occur

within 5 years, sites may be left to re-vegetate 

naturally. If not, the appropriate species will be 

established by seeding or planting.

Adequate substrate material and site 

preparation necessary for proper 

establishment of the selected plant species 

shall be included in the plan.

Where planting and/or seeding is necessary, 

the minimum number of native species to be 

established shall be based on a reference 

wetland unless the objectives require a 

different plant community.

• If the targeted hydrophytic vegetation is 

predominantly herbaceous, species 

diversity will be maximized as appropriate 

to meet the targeted functions. Seeding 

rates shall be based upon the percentage 

of pure live seed and labeled with a current 

seed tag from a registered seed laboratory

identifying the germination rate, purity 

analysis, and other seed statistics.

• Where the dominant vegetation will be 

forest or woodland community types, 

vegetation establishment will include a mix 

of woody species (trees and/or shrubs)

adequate to establish the reference 

wetland community.

CONSIDERATIONS

Soil Considerations

Consider making changes to physical soil 

properties, including:
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• Increasing or decreasing saturated 

hydraulic conductivity by mechanical 

compaction or tillage, as appropriate

• Incorporating soil amendments.

• The effect of construction equipment on 

soil density, infiltration, and structure.

Consider changes in soil bio-geochemical 

properties, including:

• Increasing soil organic carbon by 

incorporating compost.

• Increasing or decreasing soil pH with lime, 

gypsum, or other compounds.

Hydrology Considerations

Consider the general hydrologic effects of the 

enhancement, including:

• Impacts on downstream stream 

hydrographs, volumes of surface runoff, 

and groundwater resources due to 

changes of water use and movement 

created by the enhancement.

Consider the impacts of water level 

management, including:

• Increased predation due to concentrating 

aquatic organisms, including herptivores, 

in small pool areas during draw downs.

• Increased predation of amphibians due to 

high water levels that can sustain predator 

fish.

• Decreased ability of aquatic organisms to 

move within the wetland and from the 

wetland area to adjacent habitats, 

including fish and amphibians, as water 

levels are decreased. 

• Increases in water temperature on-site, 

and in off-site receiving waters.

• Changes in the quantity and direction of 

movement of subsurface flows due to 

increases or decreases in water depth.

• The effect changes in anaerobic conditions 

have on soil bio-geochemical properties; 

including oxidation/reduction, and 

maintenance of organic soils.

• The potential for water control structures, 

dikes, and macrotopographic features to 

negatively impact the movement of nontarget aquatic organisms.

Vegetation Considerations

Consider:

• The relative effects of planting density on 

fish and wildlife habitat versus production

rates in woody plantings.

• The potential for vegetative buffers to 

increase function by trapping sediment, 

cycling nutrients, and removing pesticides.

• The selection of vegetation for the 

protection of structural measures that is 

appropriate for wetland function.

• The potential for invasive or noxious plant 

species to establish on bare soils after 

construction and before the planned plant 

community is established.

• The use of prescribed burning to maintain 

wetland and adjacent upland plant 

communities.

Fish and Wildlife Habitat Considerations

Consider:

• The addition of coarse woody debris to 

provide an initial carbon source and fish 

and wildlife cover.

• The potential to restore habitat capable of 

supporting fish and wildlife with the ability 

to control disease vectors such as 

mosquitoes.

• The potential to establish fish and wildlife 

corridors linking the site to adjacent 

landscapes, streams, and water bodies

and to increase the sites colonization by 

native flora.

• The need to provide barriers to passage 

for unwanted or predatory fish and wildlife 

species.

PLANS AND SPECIFICATIONS

Plans and specifications for this practice shall 

be prepared for each site. Plans and 

specifications shall be recorded using 

approved specifications sheets, job sheets, or 

other documentation. The plans and 

specifications for structural features will 

include, at a minimum, a plan view, quantities, 

and sufficient profiles and cross-sections to 
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define the location, line, and grade for stakeout 

and checkout. Plans and specifications shall

be reviewed and approved by staff with 

appropriate job approval authority.

OPERATION AND MAINTENANCE

A separate Operation and Maintenance Plan

will be prepared for sites that have structural 

features. The plan will include specific actions 

for the normal and repetitive operation of 

installed structural items, especially water 

control structures, if included in the project. 

The plan will also include the actions 

necessary to assure that constructed items are 

maintained for the life of the project. It will 

include the inspection schedule, a list of items

to inspect, a checklist of potential damages to 

look for, recommended repairs, and 

procedures for documentation.

Management and monitoring activities needed 

to ensure the continued success of the wetland 

enhancement objectives may be included in 

the above plan, or in a separate Management 

and Monitoring Plan. In addition to the 

monitoring schedule, this plan may include the 

following:

• The timing and methods for the use of 

fertilizers, pesticides, prescribed burning, 

or mechanical treatments.

• Circumstances when the use of biological 

control of undesirable plant species and 

pests (e.g. using predator or parasitic 

species) is appropriate, and the approved 

methods.

• Actions which specifically address any 

expected problems from invasive or 

noxious species

• The circumstances which require the 

removal of accumulated sediment.

• Conditions which indicate the need to use 

haying or grazing as a management tool, 

including timing and methods.

REFERENCES:

Executive order 13112, Invasive Species, 

February 3, 1999. Federal Register: Vol.64, 

No.25. Feb. 8, 1999.

http://frwebgate.access.gpo.gov/cgibin/getdoc.cgi?dbname=1999_register&docid=

99-3184-filed.pdf

Galatowitsch, Susan, et al, 1994. Restoring 

Prairie Wetlands: an ecological approach. Iowa 

State University Press, Ames, IA. 246 pp.

Hall, C.D. and F.J. Cuthbert. 2000. Impact of a 

controlled wetland drawdown on Blanding’s 

Turtles in Minnesota. Chelonian Conservation 

Biology. Vol. 3, No. 4, pp. 643-649Hurt, 

G.W.and V.W. Carlisle, 2001. 

Delineating Hydric Soils, in Wetland Soils –

Genesis, Hydrology, Landscapes and 

Classification. Edited by J.L. Richardson and 

M.J Vepraskas. CRC Press, Boca Raton, FL 

pp. 183 – 206.

Kingsbury, Bruce & Joanne Gibson, 2002. 

Habitat Management Guidelines for 

Amphibians and Reptiles of the Midwest. 

Partners in Amphibian & Reptile Conservation, 

Ft Wayne IN, 57 pp. 

M.J. Vepraskas ands S. W. Sprecher editors, 

1997. Aquic Conditions and Hydric Soils: The 

Problem Soils. Soil Science Society of America 

Special Publication Number 50. SSSA, Inc. 

Madison, WI.

Maschhoff, Justin T & James H. Dooley, 2001. 

Functional Requirements and Design 

Parameters for Restocking Coarse Woody 

Features in Restored Wetlands, 

ASAE Meeting Presentation, Paper No: 

012059.

USDA, NRCS, 2003. ECS 190-15 Wetland 

Restoration, Enhancement, Management & 

Monitoring. 425 pp.

ftp://ftp-fc.sc.egov.usda.gov/WLI/wre&m.pdf

USDA, NRCS. 2002. Field Indicators of Hydric 

Soils in the U.S., Version 6.0. G.W. Hurt, P.M. 

Whited and R.F. Pringle (eds.). USDA, NRCS 

in cooperation with the National Technical 

Committee for Hydric Soils, Fort Worth, TX.

ftp://ftpfc.sc.egov.usda.gov/NSSC/Hydric_Soils/FieldI

ndicators_v6_0.pdf

USDA, NRCS. Wetland Restoration, 

Enhancement, or Creation, Engineering Field 

Handbook Chapter 13, Part 650. 121 pp.

ftp://ftp-fc.sc.egov.usda.gov/WLI/wre&m.pdf

USDA-NRCS. 2000. Indiana Biology Technical 

Note 1.
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USDA-NRCS. Hydric Soil Technical Note 13, 

Deliberations of the National Technical 

Committee for Hydric Soils (NTCHS).

ftp://ftpfc.sc.egov.usda.gov/NSSC/Hydric_Soils/note1

3.pdf