L Street Beach

L Street Beach is the stretch of Carson Beach on Dorchester Bay in front of the L Street Bathhouse, where the L Street Brownies have swum year-round since 1902 and still lead a New Year's Day plunge. It is a free state beach with DCR lifeguards on Carson Beach in summer, and Save the Harbor advises staying out for 24 hours after heavy rain.

Directions

Photo: SamAu · CC BY-SA 4.0

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Latest reading · SwimScore 70/100 (Good swim) for a typical swimmer: air 15°C, wind 29 km/h, waves 1.3 m, UV 2. Updated 23 Sept, 22:00 UTC.

Know before you go

Getting in: Free public DCR beach along Day Boulevard in South Boston, facing the L Street Bathhouse (BCYF Curley Community Center, 1663 Columbia Road); Wikipedia describes L Street Beach as the part of Carson Beach in front of the bathhouse.
Lifeguards: DCR lifeguards staff Carson Beach on weekends and holidays from May 23, then daily June 13-Sept. 7 in 2026. Neighboring M Street Beach is unguarded.
Water quality: DCR samples the South Boston beaches for enterococci; in Save the Harbor/Save the Bay's report card for the 2025 season, Carson Beach scored 95% and M Street 94%. Lab results take about 24 hours, so Save the Harbor advises staying out for 24 hours after heavy rain (0.3 in/hr).
Season: DCR designated swimming season May 23-Sept. 7 in 2026; the Brownies swim year-round.
Who swims here: The L Street Brownies, organized in 1902, swim year-round and lead a New Year's Day plunge into Dorchester Bay that draws hundreds. The revived Boston Light Swim course finishes at the L Street Bathhouse.
Watch for: Bacteria levels can rise after heavy rain
Facilities: BCYF Curley Community Center with steam rooms and saunas (membership limited to Boston residents) · McCormack Bathhouse at Carson Beach with restrooms and food stands