It can be drainage from crop land, urban storm water, strip mining, runoff from construction sites, stream bank erosion, or groundwater seepage.
(It; can be; drainage from crop land, urban storm water, strip mining, runoff from construction sites, stream bank erosion, or groundwater seepage)
It
can be
drainage from crop land, urban storm water, strip mining, runoff from construction sites, stream bank erosion, or groundwater seepage