MT3D99 - The Leading Code for Analyzing Contaminant Migration in Groundwater.

MT3D99 builds on the strengths of the public-domain MT3DMS code, and includes significant new enhancements to improve performance and increase the functionality of the MT3D96 and MT3DMS codes.

New Free software upgrade available to registered MT3D99 users. The most recent version of MT3D99 is Service Pack 4. For details inquire at

Key Features:

  • Implicit Solver
    The iterative solver is based on generalized conjugate gradient methods with the highly efficient Lanczos/ORTHOMIN acceleration scheme and enables the user to solve a wide array of problems using much less computer.
  • TVD Solution Scheme
    The third-order TVD (total-variation-diminishing) scheme for solving the advection term is mass conservative and minimizes numerical dispersion and artificial oscillation. It has been shown to be effective where other solution techniques fail.
  • Dual Porosity Option
    The optional dual-porosity advection-diffusion model provides a more effective approach than the standard single-porosity advection-dispersion model for modeling solute transport in fractured or extremely heterogeneous porous media.
  • Nonequilibrium Sorption and Monod Kinetics
    The nonequilibrium sorption model enables the user to examine the role of sorption in solute transport and remediation processes without the restrictive local-equilibrium assumption. In addition to the first-order kinetics, MT3D99 supports zero-order and mixed-order Monod kinetic reactions.
  • Multispecies Reactions
    MT3D99 can handle BIOPLUME-type aerobic and anaerobic reactions between hydrocarbon contaminants and any user-specified electron acceptors, and parent-daughter chain reactions for inorganic or organic compounds. This enables MT3D99 to analyze natural attenuation and bioremediation without using an add-on package. The multispecies reactions are fully integrated with the MT3DMS transport solution schemes, including the implicit solver.
  • Automatic Restart Option
    MT3D99 supports a new automatic restart option to greatly facilitate the continuation of a run from a previous simulation.
  • Complete Mass Budgets
    MT3D99 computes cell-by-cell mass flux and mass storage terms. This enables the user to compile a detailed mass budget for any subregion of the model grid.
  • Postprocessing Programs
    MT3D99 includes several useful and flexible postprocessing programs: PostMT3D/MODFLOW for creating 2D and 3D data files for any graphic and visualization software package including Surfer and TecPlot; HCOMP for computing residuals and summary statistics between observed and model-calculated heads and concentrations; and FBUDGET for calculating detailed groundwater flow and solute mass budgets in any user-specified subregion of the model grid.

Why choose MT3D as your 3D Solute Transport Simulator?

  • Full Compatibility with MODFLOW
    MT3D99 is designed to work directly with the industry-standard groundwater flow code MODFLOW-88 and MODFLOW-96. Other flow models can also be supported by modifying the LinkMT3D package for MODFLOW.
  • Three Major Classes of Transport Solution Techniques
    MT3D99 combines three major classes of transport solution techniques in a single code, namely, the standard finite difference method; the particle tracking based Eulerian-Lagrangian methods; and the higher-order finite-volume TVD method.
  • Wide Acceptance and Support
    MT3D has been successfully applied to model thousands of sites and is widely accepted by regulators and the groundwater consulting and research community. In addition, MT3D99 is backward compatible with all previous versions of MT3D, supported by all major graphical pre- and post-processors.
  • Free Technical Support
    S.S. Papadopulos & Associates, Inc. stands behind this product 100% and provides complete documentation and free technical support for MT3D99 users.

Please contact us at for downloading instructions and technical support. Before downloading any SSP&A proprietary software, please read the License Agreement.

  • New Purchase ($700)
  • Upgrade ($250) - Upgrade from MT3D96 to MT3D99
  • To purchase a copy of MT3D99 by phone, please contact SSP&A at our Bethesda, Maryland office at (301) 718-8900.