REPORT: Clean Water Act Violations Occur Routinely [1]
In 2005, at least 3,600 facilities violated their water discharge permits more than 24,000 times, according to a US Public Interest Research Group report [2] released Oct. 11, 2007.
The violators made up more than half the major facilities reviewed by the advocacy group, after it acquired the data from EPA via a FOIA request. Many facilities dumped nearly four times what they were allowed in their permit, and some exceeded their permit six-fold. Many other smaller facilities that may be polluting weren't included in the study.
In the report, USPIRG breaks out the violations in a variety of ways, such as by state, county, number of violations, and frequency of violations. You can also download a spread sheet for all the identified major violators in each state (except for Oregon, which has not provided data to EPA since 2004).