United States Department of Agriculture 447-CPS-1

NRCS, NHCP

February 2023

Notice of Proposed Changes to the National Handbook of Conservation Practices 

for the Natural Resources Conservation Service

[Docket No. ]

PROPOSED FULL TEXT FOR PRACTICE STANDARD CODE 447

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. 

USDA is an equal opportunity provider, employer, and lender.

Natural Resources Conservation Service 

CONSERVATION PRACTICE STANDARD 

IRRIGATION AND DRAINAGE TAILWATER RECOVERY 

CODE 447 

(no)

DEFINITION 

A system designed to collect, store, and convey irrigation tailwater, rainfall runoff, field drain water, or

combination thereof for reuse in water distribution to the crop. 

PURPOSE 

This practice is used to accomplish one or more of the following purposes: 

• Improve irrigation water use efficiency. 

• Improve offsite water quality, including potential drinking water sources. 

• Reduce energy use. 

CONDITIONS WHERE PRACTICE APPLIES 

A tailwater recovery system is suitable for use on lands that have a properly designed and installed

irrigation or subsurface drainage system where recoverable irrigation runoff, subsurface drainage

outflows, or rainfall runoff are expected under current or planned management practices. 

This practice does not apply to detailed design criteria or construction specifications for individual

structures or components of the recovery system. 

CRITERIA 

General Criteria Applicable to All Purposes 

Where criteria for individual components of the tailwater recovery system are described in existing NRCS

conservation practice standards, use those practice standards and their specific criteria for planning,

designing, and installation of that component. Use sound engineering principles for the design of

components not addressed in NRCS conservation practice standards. 

Laws and regulations 

Ensure that the tailwater recovery system is planned, designed, and constructed to meet all Federal,

State, Tribal, and local laws and regulations. The landowner must obtain all necessary permissions from

regulatory agencies, or document that no permits are required. 

Utilities 

The landowner and/or contractor is responsible for locating all buried utilities in the project area, including

drainage tile and other structural measures. 

Collection 

Provide a means of collecting the water to be recovered. Ensure that the collection system is protected

from erosion damage. Collection components may include, but are not limited to, ditches, culverts,

pipelines, pumps and sumps, and water control structures, as needed. Size the capacity of the collection
components to safely handle the expected rate of flow from the irrigation runoff, rainfall runoff, and/or

drainage system, as applicable. 

Storage 

Provide a means of storing the recovered water until it can be redistributed in the irrigation or distribution

system. Include the inflow volume, inflow rate, and the required water elevation at the control point where

the tailwater is returned to the distribution system in the storage capacity design calculations. 

For irrigation tailwater design the tailwater recovery storage component to store, at a minimum, the

complete runoff from a single irrigation set, if one or more of the following conditions apply: 

• The energy sources for tailwater pump back systems are subject to interruption, 

• Safe emergency bypass areas cannot be provided, or 

• Tailwater discharge violates local or State regulations. 

Where a tailwater recovery system is used to collect irrigation tailwater, drainage tailwater, or rainfall runoff

for storage and use as irrigation reservoir replenishment, base the size and capacity of collection and

storage components on expected drainages and runoff volumes and rates. Provide an adequate outlet for

inflow that exceeds the expected storage volume. Use criteria found in NRCS Conservation Practice

Standard (CPS) Pond (Code 378). 

Protect system components from storm events and excessive sedimentation. Design sumps and

collecting basins with inlets that protect the side slopes and the collection components from erosion.

Where required by State law, provide a diversion, dike, or water control structure to limit entrance of

rainfall runoff into the designed inlet structure. 

Install sediment traps as needed. 

Conveyance 

Provide a means to convey water from the storage component to a point of entry in the irrigation or

distribution system. Conveyance components may consist of a pumping plant and pipeline to return the

water to the upper end of the field, or a gravity outlet having a ditch or pipeline to convey the water to a

lower elevation in the irrigation system. Other components or combinations of components may be

necessary as determined on a site-specific basis. 

For systems where tailwater is discharged into a collecting basin, irrigation reservoir, or pipeline that has

components for regulating fluctuating flows (e.g., a float valve), small sumps with frequently cycling

pumping plants may be used. If the storage component is not designed to regulate flows, ensure the

capacity of the tailwater sumps or collection basins is large enough to provide the regulation needed. 

Determine the capacity of conveyance components by an analysis of the expected rate of tailwater

supplied to the storage component, the planned tailwater storage capacity, and the anticipated irrigation

application or other water distribution. If the tailwater capture is used as an independent irrigation supply

rather than as a supplement to a primary irrigation water supply, ensure the rate and volume of flow is

adequate for the irrigation system supplied. 

Additional Criteria Applicable to Improving Offsite Water Quality 

Storage components 

Where additional storage is required to provide adequate retention time for the breakdown of chemicals in

runoff water, size the storage components accordingly. Use site-specific information about the chemical of

concern to determine allowable retention times. 

Where additional storage is required to provide for sediment deposition, base additional storage volumes

on site-specific information of the contributing watershed. 

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February 2023
Additional Criteria Applicable to Reducing Energy Use 

Provide analysis to demonstrate reduction of energy use from practice implementation. 

Calculate the reduction of energy use as the average annual or seasonal energy reduction compared to

previous operating conditions. 

CONSIDERATIONS 

Additional Considerations to Improve Irrigation Water Use Efficiency 

Good irrigation system design and management will limit tailwater volume to that needed for effective

operation. This may reduce the capacity of the collection, storage, and conveyance components. 

Changes in irrigation water management may be necessary to optimize the use of return flows. 

Downstream flows and aquifer recharge dependent on tailwater and rainfall runoff will be reduced and

may cause undesirable environmental, social, or economic effects. 

Additional Considerations to Improve Offsite Water Quality 

Effects on surface and ground water quality by the movement of sediment and soluble and sedimentattached substances should be considered. 

Chemical-laden water can create a potential hazard to wildlife, especially waterfowl that are drawn to

ponded water. Consider installing measures that will deter waterfowl use if the water will be hazardous to

them. 

Treatment of tailwater to eliminate pathogens that cause foodborne illnesses may be necessary if it is

used to irrigate fruits and vegetables. 

Plan nutrient and pest management measures to limit chemical-laden tailwater when practical. 

Protect system components from storm events and excessive sedimentation. 

PLANS AND SPECIFICATIONS 

Prepare plans and specifications for irrigation tailwater recovery systems in accordance with this standard

and describe the requirements for applying the practice to achieve its intended purpose. 

At a minimum, include the following in the plans and specifications: 

• Site plan layout of the tailwater recovery system and associated components. 

• Cross sections and profiles. 

• Type, quality, and quantity of the various system components. 

• Location of utilities and notification requirements. 

OPERATION AND MAINTENANCE 

Prepare an operation and maintenance plan specific to the components installed for use by the landowner

or operator responsible for operation and maintenance. Provide specific instructions for operating and

maintaining components to ensure they function properly. 

The plan will include provisions to address, at a minimum,— 

• Periodic cleaning and regrading of collection components to maintain proper flow lines and

functionality. 

• Periodic checks and removal of debris as necessary from trash racks and structures to assure

proper operation. 

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February 2023
• Periodic removal of sediment from traps and storage components to maintain design capacity and

efficiency. 

• Inspection or testing of all pipelines and pumping plant components and appurtenances, as

applicable. 

• Routine maintenance of all mechanical components in accordance with the manufacturer’s

recommendations. 

REFERENCES 

USDA NRCS. 1983. National Engineering Handbook (Title 210), Part 650, Engineering Field Handbook,

Chapter 15, Irrigation. Washington, D.C. 

USDA NRCS. 1993. National Engineering Handbook (Title 210), Part 623, Chapter 2, Irrigation Water

Requirements. Washington, D.C. https://directives.sc.egov.usda.gov/

USDA NRCS. 1997. National Engineering Handbook (Title 210), Part 652, Irrigation Guide. Washington,

D.C. 

USDA NRCS. 2012. National Engineering Handbook (Title 210), Part 623, Chapter 4, Surface Irrigation.

Washington, D.C. 

USDA NRCS. 2016. National Engineering Handbook (Title 210), Part 623, Chapter 8, Irrigation Pumping

Plants. Washington, D.C. 

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NRCS, NHCP

447

February 2023