Not that long ago, the concept of swimming in Baltimore’s harbor seemed like a joke.

Its waters were perennially plagued by discharges from the city’s sewage treatment plants and laden with historical pollution from the factories and industrial sites that once lined the waterfront.

Today, river otters and herons are returning to corners of the harbor, residents regularly kayak and sail, and — amazingly — people are beginning to swim. For the second year in a row, the group Waterfront Partnership plans to hold its Harbor Splash swimming event in Fells Point (An earlier swim date in June was postponed because of rain).

The organized swim is a milestone in the vision of Mike Hankin, a Baltimore County businessman and philanthropist who has championed a swimmable harbor for more than 15 years. The longtime board chair of the Waterfront Partnership of Baltimore, Hankin launched the group’s Healthy Harbor Initiative in 2010 with a mission to make the water body swimmable within the decade.

Cities around the world are attempting similar things with their central waterways — Paris recently reopened the Seine River to swimming after a century-long ban was lifted — and Hankin sees Baltimore as a leader in this global campaign. Ahead of Saturday’s scheduled swim, The Banner spoke with him about what comes next.

Hankin thinks it won’t be long before Baltimore has public swim sites open throughout the summer, just about any day of the week.

This interview has been edited and condensed for clarity.

Baltimore Banner: Is it fair to say that this was your idea originally, or were there others who inspired you?

Mike Hankin: Clearly, I was very vocal, but there were really well-meaning, experienced environmental organizations thinking about the harbor long before me. To the extent I made any contribution, it was only to say, “Look, let’s pick a goal to work toward. And let’s develop a plan that we think has a reasonable chance, is logical, that can get us there.”

This is 2010. We were all in the room together. I said, “All right, let’s do a very scientific study. Everybody turn over a piece of paper or napkin and write down: When do you think the harbor could be swimmable and fishable?” People put 2050, 2040, 2015 — there were some crazies — and I said, “Well, that seemed to average out to 2020.”

Obviously, it didn’t, but to pick anything further than 2020 would have been disheartening, to say the least.

Back when Baltimore was trying to court the Olympics in the early 2000s, then-mayor Martin O’Malley wanted the Olympic triathlon to take place in the harbor. At the time, the idea seemed far-fetched to many in Baltimore. Have we seen a shift in attitudes?

Oh, amazing shift. We talked about this a lot within the Waterfront Partnership and within the Healthy Harbor effort, that we needed to get people to shift from thinking it can never happen to, “It’s got to be managed — the same way Chicago and San Francisco and Paris and lots of other cities manage it."

And also to get people to understand that it’s a very complex issue. We can talk about the health of the environment. That is, how are the fish doing? How are invertebrates doing? How are the birds doing? Which I care about deeply. There are a lot of different factors that affect that: conductivity, dissolved oxygen, clarity, nitrogen, phosphorus, they’re all related.

And then there’s bacteria. And that’s going to keep you and I out of the water.

A swimmable harbor can mean different things to different people. What’s your ideal vision for a swimmable harbor? How close do you think we are to it?

I want to see the harbor used recreationally regularly. So I want to see people sailing. I want to see people paddle-boarding, kayaking every day. And we’re there now. Even the worst of the days, we’re there now.

Now, the subset of that is, “Yeah, I want to see regular swimming. I want to see a roped-off area that looks like Chicago, Lake Michigan or the Marina District in San Francisco.”

So I think Baltimore can ultimately offer a regular place for people to go in and swim laps. And I think on a regular basis, we’re off. We’re not there today. It’s going to take more cooperation from Rec and Parks and the Health Department and the other advocacy groups to find the right place.

I don’t know where it is, but until then, I want to see regular recreational use — that people don’t think twice about saying, “I’m going to go kayak for lunch.”

When it comes to swimming, how far off do you think we are from, say, regular swimming in a roped-off area?

I think it’s something that we’ll figure out in the next two years. There are some days I look at the water, I say, “If I had nothing else to do, I would love to jump in and swim.”

I want to get to testing. Healthy Harbor is doing its testing. Blue Water Baltimore is doing its testing. The Department of Public Works is doing its testing. We need to come up with a single source where we take the combined efforts for testing and we test bacteria, we test DNA regularly, we test for vibrio. And then we agree to make this available by 10 o’clock in the morning for that day.

Not everyone agrees with your premise that we’re basically there in terms of having a harbor that is safe for swimming on many days of the year. Blue Water Baltimore is an example of an organization that doesn’t participate in Harbor Splash, and their emphasis is different from Waterfront Partnership’s. Do the concerns that Blue Water raises feel legitimate to you? Do you think their emphasis is in the wrong place?

I think if we back up a second and look at what they’re saying before they get to their conclusion, they’re saying very similar things. That, on bacteria, there are days when the water’s very clean. And there are days, I think limited to after a really, really bad rainstorm, where they’re not. So that’s one point. The second point is, if you swim on days where it’s really bad, you’re taking a chance, right? Everybody is saying those two things. I don’t want to go in the harbor a day or two after the rain. I don’t want to go in Lake Michigan or the marina in San Francisco or the Charles River.

Then you get to the next point. Where Healthy Harbor and Blue Water begin to diverge is [that] Healthy Harbor is very clear that we need to manage this body of water and make it clear when it’s safe to swim and when it’s not safe to swim. And we believe that at that point, the individual can make a decision for himself or herself.

Blue Water’s goal is the entire ecosystem. And they’re both really, really important goals. And what Blue Water — this is my opinion — is saying is, “When we get to this point, don’t stop.” And I think that that’s a really important point. We’ve made a lot of progress, but it’s just one more step along the way.

We’ve gotten a ton of rain this week. It seems like there’s a decent chance things get cancelled this weekend. If that happens, do you see that as a blow to the bigger picture effort?

I’m not as worried about it today. What I’d like to do is just to try to come up with a more spontaneous, “Hey, it hasn’t rained in a week, let’s swim tomorrow.” Something like that.

I was really worried about it for the kickoff. I was very worried that if we had to cancel it, that people wouldn’t understand. We would all be disappointed, but they wouldn’t be able to put it into perspective. Because that same year, the group working on the Anacostia River in Prince George’s County [and in] Washington, D.C., were having their first event, and they had to cancel it.

People are also seeing what happened with Paris. They couldn’t hold all the swimming that they wanted to have, but they held some. And then this past week, they opened it up on a regular basis.

There seems to be a lot more awareness now, in part because of the Paris story.

I’m biased, but I think Baltimore has been a leader in this.

If you think that within two years we can have roped-off swimming areas, it sounds like you think we’re close to the dream that you laid out in 2010.

I think it’s largely logistical at this point.