For years, the Chizuk Amuno Congregation in suburban Baltimore had a lake it didn’t want on its front lawn.

“Lake Chizzie” was the Baltimore County synagogue’s flooded parking lot, created when rainwater pooled on the low-lying portion of a paved surface large enough to accommodate the 1,200 member families’ cars. On the other side of the main building, near the pre-school, was another parking lot cum lake: a lot that often flooded and, in the winter, created ice hazards for children.

The synagogue leadership knew that the flooding was not only an unattractive and sometimes dangerous nuisance, but also a staging area for polluted stormwater runoff that would eventually find its way to the Chesapeake Bay. They sought ways to fix it, eventually receiving $240,000 in funds and in-kind assistance from the Chesapeake Bay Trust, the Maryland Department of Natural Resources and Blue Water Baltimore.

With that money, they turned the unwanted lake bed into two bioretention gardens — shallow vegetated basins that receive stormwater directed into them from drains, then use that water to feed native plants. In the other problem area, a smaller garden, about the size of a school bus parking space, has made the school entrance more attractive and eliminated a hazard — all while making congregants feel good about their gemilut hasadim (Hebrew for an “act of loving kindness”) to the Earth.

“You drive up here, and you see this, and it shows what our priorities are,” said Glenn Easton, Chizuk Amuno’s executive director. “It’s in your face.”

Chizuk Amuno is one of 16 congregations — three synagogues and 13 churches — that have signed on to a regional interfaith program called One Water Partnership. To join the partnership, congregations must commit to take major actions to improve the health of the Jones Falls watershed. The goal: remove 15,000 square feet of impervious paved surfaces and install 5,000 square feet of rain gardens. Jones Falls, which flows from suburban Baltimore County through the heart of the city to the Inner Harbor, is among the most polluted waterways in the Bay watershed.

The Interfaith Partners of the Chesapeake, an Annapolis-based nonprofit organization, started the One Water effort to build on successes they’d had with individual congregations.

Many faith leaders only realized their buildings were contributing to stormwater runoff after the state passed a law requiring a fee for stormwater treatment in Maryland’s 10 largest jurisdictions. The fee was based on square footage of impervious surfaces, so congregations like Chizuk Amuno would have been out thousands of dollars, Easton said. And though the legislature overturned the fee mandate, and Baltimore County eliminated its fee (the city still has one, and collects close to $30 million a year), many institutions of faith still wanted to do their part.

For many spiritual leaders, the work is an extension of their stewardship of creation and important to their faith. With more than 600 churches in Baltimore City and hundreds more in the county that wraps around it, small works can add up to a significant difference, said Jodi Rose, executive director of Interfaith Partners.

“It’s humbling to think that we are the last lines of defense. If we don’t do it, who will?” she asked. “This is our work. This is our time.”

The projects range from large, expensive retention gardens like the one at Chizuk Amuno to plans for more rain gardens, organized stream cleanups, “creation” walks in nature and tree plantings. Brown Memorial Church in the city’s Bolton Hill neighborhood will be screening the climate change film, Merchants of Doubt, followed by a panel discussion. Chizuk Amuno is one of the few that have completed projects. The other organizations have signed commitments to do so.

Even so, at least some are following Chizuk Amuno’s example and thinking big. At Church of the Redeemer, an Episcopal congregation in North Baltimore, the green team includes environmental writer Laurel Peltier, master gardener Martha Ruffin and environmental design consultant John Campagna, who was just named the new executive director for the anti-sprawl nonprofit, 1,000 Friends of Maryland.

The church team has plans to divert stormwater into tree pits and improve the drainage systems for its parking lot, which accommodates 2,000 parishioners. They also would like to put a solar canopy over the lot to reduce their electric bill. The parking lot project alone will cost about $300,000, they estimate. Like Chizuk Amuno, they hope to get grants from the Chesapeake Bay Trust and the National Fish and Wildlife Foundation, as well as in-kind design and planning help from Blue Water Baltimore.

The church, which has long had a green ethos, already installed a rain garden in what was once called the “mud hole,” an area next to its school playground. It used to flood constantly, Ruffin said, and children had to change their clothes after playing outside in it.

“Now, when you are out here in a storm, it really captures almost all the rain,” she said.

Mark Cameron, watershed liaison for the city’s Department of Public Works, said even if the institutions meet their goals, it eliminates only a tiny fraction of the vast acreage of impervious surface draining into the Jones Falls. But, he said, the churches and synagogues can reach far beyond their parking lots and into the homes of their congregants, who in turn can inspire their neighbors. It could lead to small changes, from less drain-clogging trash on the streets, to bigger ones, such as homeowners looking into their own stormwater practices and installing rain barrels or curtailing their pesticide use.

“The other message they’re getting to people is, ‘Here’s what you can do. Simple actions you can take on your property,’” Cameron said. “It means more when they’re hearing that from their peers [rather than] from the city.”

Instead of fighting fees, the faith leaders say, they should be “evangelists” for the environment — spreading the word that it’s an act of faith to care for waterways.

“We have a moral imperative rooted in the belief that God calls us to engage in actions for the good of all. And creating a sustainable environment is an act of love,” said Mary Gaut, Interfaith Partners’ board chair. “If you think about it, a watershed is the most basic neighborhood we have. It has been a neighborhood forever…we now have the benefit of seeing what these individual actions add up and make a big difference. It is the essence of thinking globally and acting locally.”

Organizers hope that, as part of the One Water program, they can organize a bus trip to show the congregations that are just starting out how finished projects look in the end. If the tour happens, Chizuk Amuno will be one of the first stops. And if the bus stops by on a rainy day, said Cheryl Snyderman, the congregation’s director of Gemilut Hasadim, they might get a sense of the old “lake” view, with its new catchment in place.

“When it rains, we still have Lake Chizzie,” Snyderman said. “But it’s controlled now.”