Recently, I attended a seminar on planting for clean water presented by the Dakota County Soil and Water Conservation District (Dakota County SWCD), Blue Thumb and the city of Eagan. Living in the Land of 10,000 Lakes and truly enjoying sitting on our deck looking out over a man-made pond each summer, we have a vested interest in how we plan and care for water management in our yards.
Just counting those with a surface area of an acre or more, there are about 200 natural lakes and wetlands in Eagan, and almost all are part of a stormwater drainage system. Adding in the man-made waterbodies, there are over 1,200. The stormwater management area shared with my neighbors "across the pond' is much smaller than that, but it supports quite a bit of wildlife. From the time the ice is out (nice and early this year) until it freezes over again in December, we watch for the returning ducks and mergansers to hatch new generations of their families, listen for the frogs to start their springtime serenades (a couple just started last night), and we smile when the turtles wake up and start sunning themselves on the big rock again.
You may not have a waterbody on your property like we do, but chances are, you enjoy time at a lake or on a river - Minnesota has the highest percentage of people vacationing in the state where they live. You've also got a roof over your heads, rain gutters and downspouts to divert water away from your foundation, a driveway, sidewalks and probably a little bit of lawn. Everyone of those contributes to runoff and adds to the stormwater management system. If we don't do a better job of restoring some of the native plantings that used to handle rainfall, more of our waterbodies will be turning green instead of blue.
That was the topic of the seminar - how to take advantage of native plantings to provide an attractive part of your yard that also serves to improve the water quality in and around our neighborhoods. The principles are simple - restore the natural processes for handling water after a rainfall. In pre-settlement times (about 200 years ago), about 15% of a rainfall would more than could be absorbed by the ground or taken up by the plants, shrubs and trees. Today, close to 55% of rainfall is runoff - the average 1/4-acre home lot adds over 150,000 gallons of water into the stormwater management system each year.
What are the things we can do? There are 3 main sources of water runoff we can manage better -
- Water coming off our roofs through the gutters and downspouts
- Water running off our driveways and sidewalks
- Water not being absorbed by our lawns
Rooftop gutters and downspouts are designed to keep your home's foundation dry by collecting the water and diverting it away from your house. Unfortunately, the farthest this water usually gets is your driveway or a swale that sends the water out into an already saturated lawn or out to the street. The average home foundation footprint of 1,500 square feet will receive 900 gallons of water during a 1" rainfall.
- Make sure your downspouts are not directing water out to your driveway.
- Install rainbarrels, available at most home improvement stores.
- Eagan's Rainbarrel installation guide
Drivewary and Sidewalk Runoff
Impervious surfaces, like concrete and asphalt don't absorb any water, they just deflect it. And, these 2 things do receive a fair amount of water during a rainfall, spilling it out into the street and on to the stormwater management system. There are new pervious systems for driveways and sidewalks, but it can be expensive to rip up your old surfaces, prepare the base and put down the new surface. Of the 3 areas - rooftop, lawns and driveways and sidewalks, this is the smallest area, but you'll still have about 600 gallons of runoff during each 1" rainfall.
- Keep additional water from being diverted onto impervious surfaces - install planting beds with deep-rooted plants and designed with the proper elevation
- Keep your driveways and sidewalks clean and clear of grass clippings, leaves, oil, gas andpet waste. When these get washed into the storm drains, they increase the need for water treatment and will decrease water quality
Turf grass has one of the highest input needs of any plant selection - lots of water, fertilizer and 'weed' killer. Even though they need lots of water, lawns are not very efficient in handling large amounts of water. Their roots are quite shallow, so turf grasses need frequent, shallow watering. Because the roots don't go deep, excess water is not sent down further into the soil, but it turns into runoff instead. Lawns, by far, are the biggest contributor to runoff - after absorbing what they can of the 5,000+ gallons that fall on it during a 1" rainfall, almost 4,000 gallons of water becomes runoff.
- Increase mowing height, which increases root depth
- Mulch clippings instead of bagging. This reduces the need for fertilizers and herbicides.
- Make sure your watering system only waters the grass, not the sidewalks, driveway or street.
- Reduce the amount of turf grass, either by replacing it with deeper-rooted grasses, alternative groundcovers or by installing planting beds with native varieties that have deeper root sytems.
- Water Smart Lawns
These are gardens specifically designed to capture large amounts of water and integrate it back into the soil. When properly designed, they do not have standing water in them for more than 24 - 48 hours after a rainfall. The beds have a multitude of styles, native and cultivar plant selections, sizes and placements, suited specifically to your yard.
How are you handling the water in your yard? We'd love to hear what you're doing.