Wasn't just removing trash. Drove heavy machinery (excavator) into the stream bed to remove silt thereby changing stream hydraulics and releasing silt downstream further degrading water quality and potentially smothering fish, invertebrates and vegetation. Used backhoe to uproot vegetation from stream bed making it more susceptible to future erosion. Dumped and left materials on the streams flood plain which could alter hydraulics in a flood.

As an environmental lawyer he knows permits and extensive planning needed when changing streamflow. (EDIT first comment after just reading links, just followed up with video links, a bit of a puff piece but monitoring/surveying/planning was done END EDIT) As a lawyer and an officer of the court is held to a higher ethical standard than ordinary civilian. Despite this he first conspired to break the law, and then proceeded to break the law. Not a minor transgression, deserves more than a minor punishment. EDIT Not minor transgression but with some mitigation already done, perhaps lessor punishment