Several management-oriented, surface water quality models are available for TMDL (total maximum daily load) estimation. These include EPA's QUAL2E and WASP models and the Corps of Engineer's CEQUALW2 framework. Unfortunately, most of these frameworks employ kinetic representations developed prior to 1980.

The present talk outlines a new framework that incorporates some of the key scientific advances developed over the intervening years. These include mechanistic sediment-water interactions (i.e., SOD and nutrient fluxes), attached plants, and organic carbon speciation.

The model is implemented with an interface developed with the Excel/VBA (Visual Basic for Applications) programming environment.