Local voters will head to the polls on May 20 to decide whether two lighted turf athletic fields, a grass practice field, and an access road and parking lot should be built with private funds at Caryl Park on Dedham Street. The question on the town election ballot is not binding, but Parks and Recreation Commission chairman Rich Oasis has said his board would abandon its plans for the Caryl Park complex if a majority of voters are against the proposal. Oasis has said growing enrollment in youth sports has created a need for more fields in town. He said his board considered other sites, but believes Caryl Park is the best place for the facility, which would be used by boys’ and girls’ soccer, field hockey, football, and lacrosse teams. A vocal group of park neighbors and other residents has opposed the proposal, however, saying the town-owned open space should be preserved as walking and hiking trails. Opponents also cite environmental concerns related to wetlands at the site. The Town House polls will be open from 7 a.m. to 8 p.m. on May 20.