There are tips for birding Pickering Ponds in Birdwatching in New Hampshire, pp. 83-85.

The Rochester Wastewater Treatment Plant is one of those places that does not look spectacular but attracts an incredible diversity of interesting birds. This is one of the premier (but little-known) gull-watching spots in New England. A series of active and defunct wastewater treatment ponds serve as a loafing area for thousands and thousands of gulls that commute daily from the coast or even farther to feed at the nearby landfill. Waterfowl are also numerous and frequently stay quite late into winter because the warmth and aeration of the treatment ponds keep them open.

Take Exit 12 off the Spaulding Turnpike (be careful if you are coming from the south, as this exit is immediately after exit 11 and is easily missed). Head south on NH-125 off the exit ramp until the first light. Take a left at the light onto Main Street which soon crosses a bridge and becomes Pickering Road. Soon, you will see the gated entrance to the plant on your right (if you reach Tebbetts Road, you have gone too far). The treatment plant is open Monday through Friday from 9 AM (perhaps earlier) until 3 PM. Pass through the open gate and park in the lot in front of the office building. You must check in with the staff in the building before birding the plant. Leave your car in the lot as they do not like people driving out on the dikes. Be sure you are out of the plant before 3 PM so the plant staff do not have to come and get you. State birders have worked hard to maintain a positive relationship with plant staff and it is essential that such a relationship continues.

Once you have checked the treatment plant, head back to Pickering Road and take a right. After a mile or so, take an inconspicuous drive off to the right opposite mailbox #374 and park in the lot at the end. Walk through the gate to access Pickering Ponds Trails, which has no special hours and is normally publicly accessible.

This location has probably produced more gull species than any other single spot in the state, with rarities such as Franklin’s, Slaty-backed, and Thayer’s (pending acceptance by the NHBRC) Gulls on the list. White-winged Gulls are a specialty, with counts of over a dozen Iceland and half-a-dozen Glaucous being regular. Lesser Black-backed Gull is a frequent visitor as well. Sometimes the gulls loaf at Pickering Ponds, but they are more often at the treatment plant. November and December are generally best for gulls. Numbers vary throughout the season, week, and even day, so some visits are less productive than others. Waterfowl can be numerous, with teal, pintail, shoveler, wigeon, scaup, or Ruddy Duck regularly joining the local Mallards and American Black Ducks and occasionally lingering into winter. Rare species like Eared Grebe, King Eider, and Barrow’s Goldeneye have even stopped in on these small ponds! The ponds can produce a few shorebirds in season, especially if water levels are suitable. Buff-breasted and Baird’s Sandpipers have been recorded among more common species. Keep an eye open for raptors in the area, as Bald Eagles are frequently seen passing overhead and startling the gulls. Passerines are to be watched for at Pickering Ponds, with nesting Brown Thrasher in the area and Fish Crow and Northern Shrike are seen on occasion.