Notice of Implementation of the Water Erosion Prediction Project (WEPP) Technology for Soil Erodibility System Calculations for the Natural Resources Conservation Service

AGENCY:

Natural Resources Conservation Service (NRCS), U.S. Department of Agriculture (USDA).

ACTION:

Notice of availability of WEPP for soil erodibility system calculations scheduled for implementation for public review and comment.

SUMMARY:

Notice is hereby given of the intention of NRCS to implement the WEPP technology to replace the use of the Revised Universal Soil Loss Equation, Version 2 (RUSLE2), where applicable.

DATES:

Effective Date: This is effective November 17, 2016.

Comment Date: Submit comments on or before December 19, 2016. The final version of the new WEPP water erosion prediction technology will be adopted after the close of the 30-day period, and after consideration of all comments.

ADDRESSES:

You may submit comments, identified by Docket Number NRCS-2016-0009, using any of the following methods:

• Federal eRulemaking Portal: http://www.regulations.gov . Follow the instructions for submitting comments.
• Mail or hand-delivery: Norman Widman, National Agronomist, Ecological Sciences Division, Natural Resources Conservation Service, 1400 Independence Avenue Southwest, Room 6150, Washington, DC 20250.
• Email: norm.widman@wdc.usda.gov.

NRCS will post all comments on http://www.regulations.gov . In general, personal information provided with comments will be posted. If your comment includes your address, phone number, email, or other personal identifying information, your comments, including personal information, may be available to the public. You may ask in your comment that your personal identifying information be withheld from public view, but this cannot be guaranteed.

FOR FURTHER INFORMATION CONTACT:

Norman Widman, National Agronomist, Ecological Sciences Division, Natural Resources Conservation Service, 1400 Independence Avenue Southwest, Room 6153, Washington, DC 20250.

SUPPLEMENTARY INFORMATION:

The RUSLE2, an empirical erosion prediction model for calculating sheet and rill water erosion, is being replaced by WEPP technology for selected highly erodible compliance applications. The WEPP model is for use where water erosion is the primary causal factor for comparing the annual level of erosion before conservation system application to the expected annual level of erosion after conservation system application (i.e., substantial reduction for highly erodible land conservation). The use of the Universal Soil Loss Equation (USLE) to calculate potential erodibility remains unchanged. The regulation for USLE is located at 7 CFR 610.14.

The implementation of the WEPP technology does not affect the highly erodible soil map unit list contained in the NRCS Field Office Technical Guide as of January 1, 1990. The factor values from the 1990 list will continue to be used for all erodibility index calculations, including sodbuster determinations and review of previous determinations.

The WEPP technology computer model is a process-based, daily time-step model that predicts soil erosion by simulating the fundamental processes controlling water erosion. WEPP calculates sheet and rill erosion rates and sediment deposition and delivery. The WEPP model also provides the user with spatial information regarding soil flux, deposition, and loss from specific regions of a field over time. The model is intended for conservation planning, assessing water erosion for NRCS' National Resources Inventory, and aiding the development of regional and national policy.

The WEPP modular design is amenable to incorporation of new features; thus, WEPP utility also is for estimating long-term soil productivity, the effect of climate change on crop growth and erosion, sediment depositional loading of lakes and streams, and ephemeral erosion prediction.

Further, WEPP aids in calculating onsite and offsite economic costs of erosion and assessing impacts of management strategies on public lands when used in conjunction with other models.

A complete summary of the processes utilized by the WEPP model can be seen in “WEPP Model Documentation” on the USDA Agricultural Research Service Web page at http://www.ars.usda.gov/Research/docs.htm?docid=10621 . Additional WEPP documents also are also available on this Web page.

The proposed implementation timeframe for WEPP in each NRCS field office with a water erosion concern is December 1, 2016. Section 1201(a)(11)(C) of the Food Security Act of 1985, as amended, (16 U.S.C. 3801(a)(11)(C)) requires NRCS to make available for public review and comment all proposed changes to equations to carry out the highly erodible land provisions of the law in a manner consistent with section 553 of title 5.