The Green River Swimming and Recreation Area is Greenfield's town swim spot, a 22 acre park on Nash's Mill Road where a low dam across the Green River backs the current up into a wide, slow pool. The town calls it an in stream swimming pool, which is exactly right. This is river water, not a chlorinated tank. Regulars call the deep water "The Pool," and the sand strip along the south bank shows up on maps as Greenfield Beach.

The Green River comes down out of the hills of Leyden and Colrain before it meets the Deerfield a short way below the park, and it carries that upland chill with it. Even in late July the water off the beach stays bracing, and the shaded upstream end of the impoundment runs colder still. Depth builds gradually from the sand, so the near edge suits small kids while the far side against the wooded bank goes well over your head. You can walk out onto the dam itself, which doubles as a footway.

The south side holds the beach, a toddler play area, a fenced playground, restrooms and showers, a covered pavilion with a permanent grill, and a snack shack. A dozen benches sit along the back of the sand looking out over the water, and stone walls and steps laid by Depression era crews still edge the lawn. WPA workers put up a new bathhouse here in 1936, after the town took title to the land in two grants, one in 1929 and one in 1933. Cross the pedestrian bridge to the north side and you get roughly 35 numbered picnic tables under mature shade trees, no beach, and concrete stairs down into the river.

The 2026 season opens on the weekends of June 6 and June 13, runs seven days a week from June 20 through August 23, then finishes on the weekends of August 29 and September 5 through 7. Weekdays 11 to 7, weekends 10 to 8, snack shack noon to 6. Greenfield residents pay $5 adult, $4 youth and $3 senior at the gate. Non residents pay $10, $8 and $6. Under 3 is free and everyone pays half price after 5 pm. Season passes run $65 for a resident family and $95 for a non resident family.

Know the hazards before you drive up. Water quality is tested weekly under the state bathing beach code, and this stretch has a history of failing it. An E. coli spike delayed the 2024 opening, and cryptosporidium and giardia closed swimming for weeks in 2022, so check for a posted closure first. Heavy rain moves gravel and reshapes the channel, which means the bottom is not the same every year. Staff clear the river for lightning and reopen 30 minutes after the last thunder. Anyone under 9 needs a companion who is at least 16, and dogs are banned from June 1 through November 1. Parking is a gravel lot off Nash's Mill Road, and the Riverside Community Path links the park to downtown Greenfield about a mile and a half southeast.