The conservancy is holding two special events in July, bringing in life guards for safety and entertaining features to showcase the waterway’s progress.

The Charles, whose pollution was once notable enough to inspire The Standells classic “Dirty Water,” is now clean enough to accommodate swimmers — though jumping in is strongly discouraged for most of the year.

For the third straight summer, The Charles River Conservancy is inviting people to take a dip in the river that runs between Boston and Cambridge.

“We just want the river to be open and accessible for people,” said SJ Port, a spokeswoman for the conservancy.


Swimmers can wade into the waters on July 14, from 3 p.m. to 7 p.m., and again on July 25, from 10 a.m. to 3 p.m.

The swimming series, which is in a designated area of the river, is free, but organizers are encouraging attendees to make donations so that they can continue the tradition.

Swimmers have to sign up for the events to secure a spot. Each swimmer will get a 30-minute time slot.

The first community swim was held in 2013. The Conservancy; the Charles River Swimming Club; and the Department of Conservation and Recreation, the state agency that oversees the parkland surrounding the river sponsored the events. It was the first public community swim in the Charles in more than 50 years, according to officials.

Last year, organizers hosted the swim events on two Saturdays. But in order to cater to a different crowd, they opted for a midweek offering this time around.

“The people who come into the city and commute don’t get to engage in the water,” said Port. “But now when you get off work, if you want to cool off after dealing with colleagues all day, you can jump in the river.”


Event organizers believe this year will also prove popular, and they hope that in years to come there will be a more permanent spot along the Charles where people can swim at their leisure, instead of on designated days.

“We would love to have that,” said Port. “And I think we are closer to doing it than we had originally thought.”

Steve Annear can be reached at steve.annear@globe.com. Follow him on Twitter @steveannear.