On March 9th there was one adult Great Cormorant in breeding plumage actively diving in the middle of the pond. On March 11th it was gone. On March 12th there were two adults in breeding plumage observed in the middle of the pond for a few minutes. These sightings constitute the 1st, 2nd, and 3rd eBird records for Milton.
After receiving an email of a sighting of a Red-necked Grebe on March 10th, I saw it the next day on March 11th. On March 12th there were two. As far as I know they are still there. These two birds constitute the 1st and 2nd eBird records for Milton.
In their wintering range both the Great Cormorant and the Red-necked Grebe are most common along the ocean shore, rarely being found on small ponds. However, the Great Cormorant will also inhabit areas of river near the ocean. In Milton there seems to be only about four areas of water that are reasonably productive for waterbirds: the Neponset River, Turners Pond, Popes Pond, and the Wollaston Golf Course pond.