We describe a modeling suite of Matlab functions for simulating nonpoint source (NPS) pollution in groundwater aquifers. The NPS model simulates groundwater flow and contaminant transport from a large array (order of 102 – 107) of spatially distributed sources with time-varying pollution strength to a similarly large array of spatially distributed production wells (receptors) using the streamline transport approach. The code solves three equations: steady-state groundwater flow, particle tracking, and transient advection dispersion contaminant transport. The code performs convolution integration in its predictive step. Written in highly efficient vectorized form to avoid time consuming “for/while” loops, the code is also suitable for other groundwater flow and transport problems. The code is verified against analytical solutions and finite element software Comsol. An application illustrates 200 years of transient nitrate transport in the 2000 km2 Tule River aquifer sub-basin of the Central Valley, California, with 9000 individual nitrate sources and 1920 wells.