Opossum better know as possum. They do have color variations in their fur.

i have seen what possums look like the face of the animal i saw yesterday didnt look like a possum.

could be a nutria - looks like a beaver with a rat tail. Lives in wetlands or along streams, rivers

Not likely a nutria in NY state. I suggested a muskrat in another forum.

rhizo - good point - we do have an excess of nutria out west. However, this site: http://el.erdc.usace.army.mil/ansrp/ANSIS/html/myocastor_coypus_nutria.htm shows nutria do exist in New York, so it is not impossible. Muskrat have a slightly different tail and are smaller than nutria. The site listed gives differentiating details between muskrats, nutria, and beaver. Something to think about.