Tests have shown that floodwaters in two Houston areas have been contaminated with bacteria and toxins, according to an article on The New York Times website.
It is not clear how far the toxic waters have spread, but there have been breaches at numerous waste treatment plants.
Water flowing down Briarhills Parkway in the Houston Energy Corridor contained Escherichia coli, a measure of fecal contamination, at a level more than four times that considered safe.
The E.P.A. and the Texas Commission on Environmental Quality have expressed concern about toxic floodwaters, but have not made public the results of sampling they may have done.