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Issues of the Environment: Tracking and mapping rain gardens in Washtenaw County and measuring beneficial impacts

Susan Bryan, rain garden coordinator for the Washtenaw County Water Resources Office.
Susan Bryan
Susan Bryan, rain garden coordinator for the Washtenaw County Water Resources Office.


  • Stormwater runoff is a major cause of water pollution. It carries pollutants like trash, bacteria, and heavy metals through traditional storm sewers into local waterways. Current regional rain gardens [in the vicinity of Washtenaw County] can capture up to 11.6 million gallons of stormwater runoff after a rain. That rain is soaked into the ground and filtered by plants instead of directly entering traditional stormwater systems. That is the same volume as 2,900 tanker trucks lined up - a line of trucks that would stretch for 44 miles. 
  • To keep track of the many green infrastructure water capture projects that impact local watersheds, Washtenaw County Water Resources Commissioner’s Office, in partnership with the Friends of the Rouge and Washtenaw County’s GIS program, has launched an interactive map that records and displays residential projects that capture and filter stormwater runoff. RainScaping in Southeast Michigan is a free tool that was created to: 
    • Quantify the impact of green infrastructure (GI) - such as rain gardens, green roofs, rain barrels, habitat gardens, trees, and more. 
    • Record and celebrate new green infrastructure built by residents in the region.
    • Showcase collective efforts to protect local creeks, rivers, and lakes.
    • Inspire friends and neighbors to take on at-home green projects that impact stormwater.
    • This mapping effort is the first regional quantification of the effect of green infrastructure built by residents.

  • Rain gardens have a critical role for water quality in Washtenaw County. Water Resources Commissioner, Evan Pratt, noted “Rain gardens have come a long way. In 2015, Washtenaw County just had a few [rain gardens] scattered across the County. Now there are over 1,130 rain gardens that capture and remove pollution from stormwater.  All those gardens add up and make a direct impact on water quality.” Susan Bryan, Rain Garden Coordinator for the Washtenaw County Water Resources Office notes that over 100 new rain gardens were added in the past 2 years, with more being installed this year. 
  • The tool will allow anyone to see photos of these beautiful and beneficial gardens, and it will provide coordinates for seeing them up close in person. For those who are inspired, Washtenaw County teaches people to build rain gardens. The Master Rain Gardener class was begun in 2011. People were thirsty for this skill! And those residents serve as neighborhood ambassadors - spreading the word.
  • Every year, Washtenaw County offers the Master Rain Gardener class, which teaches residents to design their own garden for their own yard - step by step. The program trains residents to become rain garden experts, able to serve as ambassadors to their neighbors. There is probably a rain garden expert in your neighborhood, able to give advice. Washtenaw County started the Master Rain Gardener Facebook group for local folks who will gently give advice on your garden plans and conundrums.

(Source: *portions directly quoted*, courtesy of Susan Bryan and the WCWR office.)


David Fair: This is 89 one WEMU FM. And today, we reflect back on some of the recent severe storms with a better degree of calm as floodwaters have receded. But it's a fact: without stormwater mitigation efforts of the past, it would have been much worse. I'm David Fair, and welcome to this week's edition of Issues of the Environment. Beyond municipal and governmental efforts, a good number of local residents are making a difference by creating rain gardens on their properties. It helps capture and filter stormwater, and it's a proven environmental benefit. Now, there is a new interactive mapping tool available that allows us to see where all of the residential rain garden properties are in Washtenaw County and beyond. Our guest today has her galoshes imprinted all over it. Susan Bryan is the rain garden coordinator for the Washtenaw County Water Resources Office. And thank you for making time today.

Susan Bryan: My pleasure, David.

David Fair: What constitutes an official rain garden?

Susan Bryan: Sometimes, people have it, and they don't even know. It's any garden that takes the water from a hard surface, like your roof or your driveway, and lets it soak into the garden. So, it can be a tree or a perennial bed or even a shrub that has a little bit of a depression, so that the water pools there and then soaks it in.

David Fair: Is there a way to collectively measure how much stormwater all of the rain gardens in the area can capture?

Susan Bryan: Oh, yes. Right now, because we have this map and people have their rain gardens on there, we've calculated that it's about 11.6 million gallons are captured every year.

David Fair: That's hard to quantify. That sounds like a whole lot of water.

Susan Bryan: It's so much water. I was trying to think of how to explain how much water that is. And it's more than 2000 semi-trucks full of water if you think about how many semi-trucks that would be.

David Fair: Seems like I've been in that traffic jam. Yes.

Susan Bryan: Right. Now, it's a lot of water. People are doing an amazing job.

David Fair: Stormwater is obviously a major source of water pollution. It carries all sorts of things like trash, heavy metals and bacteria through the traditional storm sewers and ultimately out to our local waterways. So, if I were to intentionally create a rain garden on my property, what happens to all those contaminants? And do I need to in some way deal with them?

Susan Bryan: Nature is amazing. And some of the contaminants, like petrochemicals, are broken down by the bacteria in soils. Those are just naturally occurring bacteria, especially in good soils, soils with a lot of organic material, a lot of compost, a lot of leaves. They really break down a lot of those petrochemicals. Other things like lead, which might come off the pane of your house or something like that, are absorbed by particles. So, they're still there, but they're kind of like stuck.

David Fair: Right. And they're being mitigated away from humans.

Susan Bryan: Right. Exactly. And instead of being in the water, other things like nitrogen and phosphorus, are great in a rain garden. It's not even pollution. We want it in a garden. But in the water, it's not good.

David Fair: 89 one WEMU's Issues of the Environment conversation with Susan Bryan continues. Susan is the rain garden coordinator for the Washtenaw County Water Resources Office. The rain gardens have really taken off in popularity. And I mentioned at the outset that there's this new interactive map that shows a good number of them. It officially went live yesterday. Your office is partnered with whom to bring this map to life?

Susan Bryan: We are partially funded by the City of Ann Arbor, so, of course, we include them. But this map was built also in partnership with Friends of the Rouge. The two organizations put our heads together and made a map that not only shows all the spots, but you can look at all the photos of all those rain gardens. So, it's a fun thing for residents to just look at and tour at all the gardens.

David Fair: Roughly, how many rain gardens does it show?

Susan Bryan: Right now, it's about 1400. And these are just individuals who built an individual rain garden. So, these are people all across the metro area, actually.

David Fair: So, who goes about collecting where the rain gardens are, who has built one, and how do you entice them to put their property on the map?

Susan Bryan: I know. People have been sending me their rain gardens for years, so I've had this treasure trove of amazing photos. And now. I get to share them. And it's such a pleasure because people have done good work, and I want to share it. So, this is kind of fun for me to be able to look at all these photos, and you can see where they are and all the rain gardens in your neighborhood.

David Fair: I think sometimes we think of pollution mitigation efforts as not necessarily something beautiful. Do you have some favorite pictures that stood out to you as, "Oh my goodness! That's truly beautiful and a great idea for my house."

Susan Bryan: Oh, yes, absolutely. And I get to visit a lot of these rain gardens in person. I think I learn something new at every single one.

David Fair: Is the hope that, longer term, people are going to take inspiration from seeing the number and kinds of rain gardens that have been created in the area and then decide to create one of their own?

Susan Bryan: Yeah, that's right. And this is something that people can do from their couch. You can do a little tour of rain gardens all the way through your neighborhood. You can look at other neighborhoods, and it's just a pleasure. Even me, who I've had my finger on the pulse of rain gardens for a long time, I was even amazed at looking at this map and all the photos and what a sheer number of things that people have done.

David Fair: Once again, we're talking with Washtenaw County rain garden coordinator Susan Bryan on WEMU's Issues of the Environment. For a long time now, Susan, I believe, over a decade, Washtenaw County has offered a master class in rain gardening. Is participation continuing to grow?

Susan Bryan: Oh, yes. We have a winter class that we do online live with folks all across the metro area. And then, in-person, in the spring, we have a master rain gardener class that people can join. And then, it's also on-demand any time it's been recorded. Anyone can take it for free if they have some free time. So, if you get the urge to build a rain garden, there's all those materials out there, so you can know exactly how to do it.

David Fair: Soon, that the program takes us step through step, the process of creating a rain garden, is it expensive, either in terms of money or time expenditure?

Susan Bryan: The amazing thing is that an extensive rain garden does exactly the same amount of good as a cheap rain garden, so, if people, like, made their own compost and got splits of plants from maybe other parts of their garden or their neighbors. We also have plant swaps where people can get plants for free. The City of ann Arbor and other municipalities around have free compost. So, you can really do it almost for free if you're energetic, or you can outsource the whole thing and hire someone to build it. You could go either way.

David Fair: Right. And, obviously, how you choose to beautify it can change the cost of things, but there are options and it can be relatively low-cost.

Susan Bryan: Oh yeah. Yeah. It can be a very low cost. And it doesn't have to be huge. It can be a small little rain garden, and it still does a world of good.

David Fair: What kind of maintenance is required on an annual basis?

Susan Bryan: Well, gardeners know all about the maintenance for a garden. I think if you walk by and pull a weed every day, it's almost nothing. If you wait for an entire six months before you pull the weed, it feels like a lot. But it's just normal gardening. You just have to pull the weeds. But other than that, it's nothing special.

David Fair: So, as we collectively explore the need for more climate adaptation and consider a future that's going to require a lot more investment in green infrastructure, what role are these rain gardens going to play in mitigating environmental damage and supporting other sustainable practices?

Susan Bryan: Rain gardens are a really important part of climate adaptation because it means that the water that comes off your roof and your driveway doesn't rush downstream and cause flooding. You take care of it right on your yard. And it's really the gold standard of stormwater mitigation because it soaks that water into the ground where the water becomes clean. And also, it recharges our aquifer. And it doesn't cause flooding. So, it's really the best thing that we can do as individuals, and it's also fun.

David Fair: Now we've been talking about residential. What about commercial properties? Is this something you would like to see kind of mandated for new development?

Susan Bryan: New development does. We have new rules with Washtenaw County. The new development must provide infiltration. It's what we call it when you're talking about water into the ground. So, they're required if they have suitable soil. So, on those sandy soils and loamy soils, they're required to provide...part of their water must be soaked into the ground. And then on top of that, they have flood mitigation that they must provide. So, that's already in the rules. But if people who already have a commercial property want to put in rain gardens, we have a program to help people figure out how to do that called Community Partners for Clean Streams. And we try to give those people honor and glory and publicize their good works as well.

David Fair: Well, our time together is winding down. But, on a final note, if I had listened to this conversation today and I'm sitting on the fence as to whether or not to become actively an active participant in creating a rain garden, what's your final argument to me to put me over the top?

Susan Bryan: You know what? What keeps me in my job and what makes me happy every day that I do what I do is seen how much fun people have with this. They build a garden, and then you get to see nature grow. The flowers grow, you see beautiful birds, goldfinches. And then, people will even get so excited, they'll run outside when it rains to see the water soaking in. I mean, it's just wonderful. That's what I love seeing. It's the joy it brings people.

David Fair: Well, thank you so much for making the time today and providing the information, Susan. I appreciate it.

Susan Bryan: Thanks for having me.

David Fair: That is Susan Bryan. Susan is the rain garden coordinator for the Washtenaw County Water Resources Office and has been our guest on Issues of the Environment. For more information on the new interactive rain garden map and for more information on starting a rain garden and taking a master rain gardener class, visit our website at WEMU dot org. And we'll get you linked up everywhere you need to go. Issues of the Environment is a regular feature on WEMU, and you hear it every Wednesday. I'm David Fair, and this is 89 one WEMU FM Ypsilanti.

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