Regarding EPA. Check with the government jurisdiction (county or city) and see if the have an Environmental Protection Agency Clean Water Act Permit. They probably do. Under that permit they are held responsible for any pollutants, and the associated big fines, that get into the ground water, streams, rivers, etc. All operations within the jurisdiction have to get permits for any activities that may potentially pollute or alter ground water or other water ways. I deal with this on just about every project I do, either complying or getting a waiver for some of the documentation required. You do not get a waiver for meeting the requirements. It is not something to be taken lightly, fines usually start at 5 digits and can hit 6 without to much of a problem because they are based on each day of violation (like $25K per day, and it take you 180 days, for instance to make them happy and fix the problem).
Look here, specifically under the dredging and filling of wetlands and the enforcement sections.
http://en.wikipedia.org/wiki/Clean_Water_Act. There have been some pretty significant cases in Idaho where people with property next to streams or wetlands decided to modify the landscape and got in some really deep doo-doo. And as with most laws, pleading ignorance will not work.
You also need to check with the jurisdiction to see what other permits or approvals are required.