I pulled this from the EPA's website.
Specifically, the proposed rule clarifies that under the Clean Water Act:
• Most seasonal and rain-dependent streams are protected.
• Wetlands near rivers and streams are protected.
• Other types of waters may have more uncertain connections with downstream water and protection will be evaluated through a case specific analysis of whether the connection is or is not significant. However, to provide more certainty, the proposal requests comment on options protecting similarly situated waters in certain geographic areas or adding to the categories of waters protected without case specific analysis.
Looks like a land grab to me. There are a ton of groups getting together to fight this expansion. Here is an article about the proposal that breaks it down. It's one of the only articles I could find that wasn't full of left wing green propaganda promoting this.
http://www.schwabe.com/showarticle.aspx?Show=13558.
Here is the EPA site that defines what they want to change.
http://www2.epa.gov/uswaters