A growing number of U.S. dairy producers are realizing innovative income streams from what they are calling “brown gold.” They are using digesters to turn manure into biogas, which is later converted into compressed or liquefied natural gas, electricity or other fuels.

Farm and environmental groups are sparring over the number of animal feeding operations subject to new emissions reporting requirements and how extensive those requirements should be, as a reporting deadline approaches.

Can manure be regulated under the Resource Conservation and Recovery Act? Nearly three years ago, a federal judge said yes, it can be, in a ruling that cast a spotlight on how the dairy industry manages its waste.