• MODRET model (MODel for RETention Pond Design) was originally developed in 1991, by Nicolas E. Andreyev, P.E. as a complement to a research and development project for the Southwest Florida Water Management District (SWFWMD), Brooksville, Florida.   The scope of that research project was to develop a practical design manual for site investigation criteria, laboratory and field testing requirements, and guidelines to calculate infiltration losses from stormwater retention ponds in unconfined shallow aquifers.  Since 1990 there have been several revisions to the original model, consisting of more options and greater flexibility.  Currently, the full version model is MODRET Version 7 (updated in 2018).  MODRET is used for permit reviews by the SWFWMD, SJRWMD, FDOT, FDEP, numerous counties in Florida and other regulatory agencies.

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• MODRET Recovery was developed to perform only one of many functions of the full version.   It uses the same analytical approach as the full version model but in a spreadsheet format that allows calculation of time of recovery for a dry retention pond without any hydraulic controls.  Although this simplified model is limited to one function and one type of retention pond, it is simple to use and it is designed to generate a more accurate simulation of the shallow aquifer system through a refined MODFLOW model grid.   The model input is reduced to a single page, allowing the user to run the model quickly and efficiently without having to go through the learning curve needed for the full version model.  The model produces slightly different results, generally showing a slightly quicker recovery time, due to the finer MODFLOW model grid and a starting head set at the top of the pollution abatement volume.  For this model, the total number of model cells within the pond area was increased 25-fold, resulting in a more accurate simulation of the retention pond area and the corresponding average water elevations for each one-hour time step.