The Scientific Software Group
Scientific Software Group has a long tradition of excellence in providing the most advanced and comprehensive environmental software and publications available. Products include various types of groundwater modelling software.
www.scisoftware.com/   reviews

Haestad Methods - Your Hydrology and Hydraulics Modeling Solution
Offers various types of hydrology modeling software.
www.haestad.com/   reviews

WRCS - The Hydrology And Hydraulics Software Shop
Hydrology and Hydraulics Modeling Software.
www.waterengr.com/   reviews