United States Department of Agriculture 659-CPS-1

NRCS, NHCP

November 2022

NRCS reviews and periodically updates conservation practice standards. To obtain the current 

version of this standard, contact your Natural Resources Conservation Service State office or 

visit the Field Office Technical Guide online by going to the NRCS website at 

https://www.nrcs.usda.gov/ and type FOTG in the search field. 

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Natural Resources Conservation Service 

CONSERVATION PRACTICE STANDARD 

WETLAND ENHANCEMENT 

CODE 659 

(ac)

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 

This practice is used to accomplish the following purposes: 

• To enhance hydric soil functions (changing soil hydrodynamic and/or bio-geochemical properties). 

• To enhance wetland hydrology (dominant water source, hydroperiod, and hydrodynamics). 

• To enhance vegetation (including the removal of undesired species, and/or seeding or planting of

desired species). 

• To enhance plant and animal habitats. 

CONDITIONS WHERE PRACTICE APPLIES 

This practice applies to any degraded or non-degraded 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 (NRCS Conservation Practice

Standard (CPS) 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 (NRCS CPS Wetland Restoration

(Code 657)). 

• The creation of a wetland on a site location that was historically non-wetland. (NRCS CPS 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 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. 

Additional Criteria for Hydric Soil Enhancement 

Enhancement sites will be located on soils that are hydric. 

Changes to soil hydrodynamic and bio-geochemical properties such as permeability, porosity, pH, or soil

organic carbon levels shall be made as needed to meet the planned objectives. 

Additional 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 NRCS CPS 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 NRCS CPS Fish Passage (Code 396). 

Additional 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. 

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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: 

• 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 non-target aquatic organisms. 

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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 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. 

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REFERENCES 

Executive Order 13112, Invasive Species, February 3, 1999. Federal Register: Vol.64, No.25. Feb. 8,

1999. http://frwebgate.access.gpo.gov/cgi-bin/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://ftp-fc.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. 

USDA-NRCS. Hydric Soil Technical Note 13, Deliberations of the National Technical Committee for Hydric

Soils (NTCHS). 

ftp://ftp-fc.sc.egov.usda.gov/NSSC/Hydric_Soils/note1 3.pdf

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NRCS, NHCP

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November 2022