About NLE


The Nutrient Load Estimator (NLE) is a web-based tool that is designed to calculate the estimated nutrient and sediment loads for agricultural and urban tracts at a community-level and the impact that a best management practice (BMP) or combination of BMPs will have on those loads. NLE is a post-processor, not a simulation model, which is intended to provide results similar to results that the Chesapeake Bay Program Phase 5.3 Watershed Model (CBP WSM) would generate. NLE takes pre-BMP landuse loads generated by the CBP WSM and applies BMPs to those loads using application protocols adapted from the application protocols and processes used in the CBP WSM. The pre-BMP loads used in NLE at the tract-level represent the average pre-BMP loads for each landuse type in that land-river segment.


Water Stewardship, Inc. (WSI)

Contact information

Tom Simpson,, 301-873-2268, Suite 11, Building 7, 222 Severn Avenue, Annapolis, MD 21403

Sally Bradley,, 410-353-0329, Suite 11, Building 7, 222 Severn Avenue, Annapolis, MD 21403


The user must input tract location (state, county, Chesapeake Bay Program land-river segment), pre-BMP acres by landuse type, animals (type, number, fraction of time in confinement), and BMPs to be included in each scenario.


NLE provides the edge of stream load and the load delivered to tidal waters for nitrogen, phosphorus, and sediment with and without BMPs applied at a tract level.


NLE has a relatively simple user-interface that is intended for the non-modeler. A User’s Guide is available with detailed step-by-step directions. WSI staff is also available to provide training if necessary.

Scales of Relevance

NLE is designed for use at a tract level (e.g. farm, development, project).


NLE is a proprietary tool that was originally developed for use in farm assessments performed by WSI and in the development of farm Continuous Improvement Programs. It was designed to provide results similar to results from the CBP WSM because the CBP WSM is the model that is being used for the Chesapeake Bay TMDL. NLE’s use has since been expanded and it has been used for eco-label qualification, ecosystem service assessments, assessment of performance relative to regulatory expectations, and for National Fish and Wildlife Foundation Innovative Nutrient and Sediment Reduction Program grant proposals.


Keith Campbell Foundation, Blue Moon Fund, Aqua Fund, Oak Hill Fund