It's important to keep an eye out for construction or excavation work occuring in flood plains and streambeds. Permits from the U.S. Army Corps of Engineers are required before the work commences. Contractors may undo restoration work if they don't plan and execute mitigation measures. If you see any work going on you can contact your town or county public works department to let them know. They'll send someone by to check out the project.
Here's the link for reporting an environmental violation at the EPA.
Just this week the EPA let loose on a Erie contractor for damage to Rock Creek.