Nonprofit calls for permanent swimming area on the Charles

The Charles River Conservancy's proposed permanent swimming facility along the river.Stantec

For the past few summers, the Charles River Conservancy has offered swimmers a rare opportunity to steep in the river’s tea-colored water during the surprisingly popular “City
Splash” event.

Now, the nonprofit wants to create a lasting place where runners can stop mid-jog and plunge in, or families can lay down towels and bask in the sun before a cooling dip.

On Tuesday, the conservancy unveiled an ambitious feasibility study, crafted in partnership with the engineering firm Stantec, pinpointing a spot where the organization envisions a permanent swimming facility in a river once known for its dirty water.

The proposal calls for construction of a floating dock near North Point Park with a vegetated edge enclosing the area where people could splash around. The spot on the Boston-Cambridge line, not far from the Museum of Science, would offer sweeping views of the Leonard P. Zakim Bunker Hill Memorial Bridge.

“One of the reasons we love this location is that you can get there in so many ways. You can bike there, you can walk there, you can take the T there,” said Jennifer Gilbert, chairwoman of the conservancy’s Swimmable Charles committee. “It could be as easy as walking out your door . . . and going for a swim.”

In addition to releasing the detailed 74-page study, which included renderings of the swimming structure, the conservancy launched an Indiegogo.com campaign in hopes of raising $25,000 to fund the first stage of the project.

The money would go toward mapping the bottom of the river, analyzing its cloudiness, and regularly sampling its quality.

The nonprofit began work with Stantec, which designed the nearby Lynch Family Skatepark, last fall. Company employees volunteered their expertise to draft the proposal, which they wrapped up this spring.

The study is based on the assumption that water quality and permitting issues will be addressed by the conservancy. The company examined a total of five locations near North Point Park.

The conservancy ultimately settled on a space that’s out of the way of heavy boating traffic and features an existing dock that could be incorporated into the design.

“We wanted to find a piece of park that was ready to facilitate,” said Renata von Tscharner, president of the conservancy.

But creating a dedicated space for swimming in the Charles won’t come without challenges. To achieve its goal, the conservancy will need to work closely with local, state, and federal agencies.

The Department of Conservation and Recreation has jurisdiction of the river and North Point Park. State officials would need to analyze potential operational and construction costs, ensure public safety, and notify various stakeholders, long before a facility could be built.

But DCR was receptive, at least, to the conservancy’s idea.

“The agency welcomes the opportunity to review new and unique proposals that have the potential to increase public interest, particularly [for] first-time visitors, in the state parks system,” spokesman Troy Wall said in a statement.

Bob Zimmerman, executive director of the Charles River Watershed Association, which has worked for decades to turn the Charles from a polluted water body into the country’s cleanest urban river, said he, too, supported swimming in the river more regularly.

But a number of “significant obstacles” remain, he added, such as addressing stormwater runoff, which leads to E. coli contamination and cyanobacteria in the river that can make people sick.

“The lower basin meets swimming standards between 60 and 70 percent of the time,” he said. “But conversely, that means it doesn’t meet standards 30 to 40 percent of the time. That being said, we are working, and have been for some time, on these issues. We do believe there’s a point in the future that [swimming in the Charles] will happen, but the question is how far out that is.”

Von Tscharner said she understood the roadblocks, but remained optimistic.

“It might not be possible to swim every day of the year, but the days that it is possible, we want to have swimming available so that people can enjoy the river,” she said. “We are looking at our riverfront in a very different way than we did a decade or two decades ago.”

That’s true for Boston City Council President Michelle Wu, and the more than 300 people who signed up for Tuesday’s fourth annual CitySplash swim at a dock on Boston’s Esplanade, across the river and upstream from the proposed site.

Wu, who supports expanding public access to the river, said people think she’s crazy for planning to plunge in, given its history.

“But from my perspective, the Charles River is one of Boston’s treasures,” she said, “and we have to treat it that way.”