Stormwater Landscaping for Green Industry

By Dr. Eve Brantley

Background

Do you remember the first time you searched a creek for crayfish, swam in a river, skipped stones across a lake, or chased the Gulf waves? Chances are you’ve had a lot of opportunity to explore the more than 132,000 miles of rivers, streams and shorelines in Alabama. As you travel across the state, notice that it’s never very far between seeing a creek, river, or wetland. This network of water resources provides recreation, drinking water, power generation, and industry for the state, while also boasting the most freshwater fish diversity in the country.

With urban and suburban areas increasing, planning, implementation, and maintenance of water friendly practices by turfgrass managers plays an important role in protecting local water quality. Stormwater landscaping may be available on most of your work sites including commercial developments with large parking lots, parks and sports complexes, streetscapes, golf courses, school grounds, residential developments, and more. There is a connection between management of green spaces and water quality.

When you ask people what the number one cause of water pollution is, they likely picture big pipes spilling out dirty water. While this was once the source of most water quality problems, the Clean Water Act provided oversight and rules for what may be discharged into surface waters by industry and municipalities. Water quality has improved, but we still have streams, rivers, lakes and bays that are impacted by polluted stormwater runoff, or nonpoint source pollution. This pollution is the number one cause of degraded waters in the United States.

Pollutants such as oil and gas from streets and parking lots, excess fertilizer from suburban areas, sediment from land disturbing activities, and pet waste wash into stormdrains, roadside ditches, and streams with each rainstorm. The health of our local streams, rivers, lakes, and bays is a reflection of how we manage our landscape. What we do in a stream’s watershed is directly linked to the health of that stream. A watershed is the area of land that, when it rains, that water drains to a common water body — nature’s boundary lines.

Turfgrass managers may inexpensively and effectively manage green spaces and the stormwater that moves across and through them protecting healthy waters that we use for safe drinking water supply, fishing and boating opportunities, landscape amenities, and is home to an amazing array of life.

• Get a soil test.

• Apply fertilizers at the proper rate, using the correct application method, and best time to maximize plant uptake and minimize runoff.

• Use water wisely — irrigate only when needed and in the early morning. Check for leaks and nozzle direction. Use mulch to reduce water loss in plant beds. Consider using rainwater harvesting.

• Only rain should enter the stormdrain — avoid blowing grass clippings, leaves, excess fertilizers or other materials into stormdrains.

• Keep soil covered — limit erosion with temporary and permanent seed or mulch to protect from soil loss.

• Consider implementing practices such as grass swales, rain gardens, and more to slow and clean stormwater.

• Manage a streamside vegetation buffer along streams and ponds to filter stormwater. Pollinator plants may be incorporated for an aesthetically pleasing look that is also ecologically valuable.

Don’t Guess — Test!

One of the best ways to protect streams also protects your wallet. Knowing the fertilizer needs for lawns and applying only the required amount means that chemicals (and money) aren’t wasted. One application of excess fertilizer may not be a big deal, but 100 excess fertilizer applications in a watershed can create problems such as harmful algal blooms.

ATA members can help get the word out to homeowners and others about the importance of proper fertilizer application rate and timing to promote a healthy landscape and improve stormwater runoff. Simple tips and planning make a big impact. Inform others how to soil test, avoid applying chemicals before a rain event, create ‘water zones’ for plants with similar water needs, and incorporate native plants in landscapes that are adapted to your area to reduce inputs and add benefits to pollinators.

Stormdrain Connection

Turfgrass managers should remind people that only rain should go down a drain. The stormwater flowing across urban and suburban landscapes to stormdrains (Photo 1) is not treated before entering local waters. That means, whatever the stormwater is carrying has the potential to get into your stream, river, or lake. Lawns and other turfgrass areas play an important role by increasing stormwater infiltration that minimizes excess fertilizer reaching stormdrains. If we approach managing green spaces to limit pollutants that are allowed to move off site, we’re taking an important and smart stewardship approach. Also, allowing grass clippings, fallen leaves, or other yard waste to be blown into a stormdrain can lead to clogging that results in localized street flooding.

Photo 1: Stormdrain

Use Water Wisely

The US Environmental Protection Agency estimates that a typical American family uses around 320 gallons of water per day. Of this, 30 percent, or 96 gallons, is for outdoor water uses and most of that is for lawn and garden irrigation. A surprising statistic is that more than 50 percent of outdoor water that is applied is actually wasted. Water smart actions like watering in the early morning and only when needed can save water, energy, and money. Installing soil moisture sensors and checking that nozzle heads are not sprinkling the street or your neighbor will help with effective irrigation.

If you’re looking for ‘free’ water, rainwater harvesting is an ancient practice that is still popular. Rain barrels or larger cisterns capture rain and store it for use at a later time. A 1,000 square foot roof top will provide 600 gallons of water in a one-inch rain and Alabama on average receives 55 inches of rain a year.

Green Industry + Green Infrastructure

Landscape and turfgrass professionals have a unique opportunity to integrate rainwater, plants, and soil in a way that benefits their clients on multiple levels from aesthetics to improved water quality. Green infrastructure is an approach to managing stormwater that mimicks natural water flow by slowing stormwater down and allowing it to soak into the ground before directing it to traditional stormwater infrastructure like stormdrains. Slowing stormwater runoff and allowing it to soak into the soil is key to filtering out the pollutants that it may be carrying. Lawns and other turfgrass areas play an important role by increasing stormwater infiltration and capturing excess fertilizer before it reaches stormdrains that empty into local streams. Popular green infrastructure practices include permeable pavement, rain gardens, grassed or vegetated swales, and bioretention cells.

Stormwater can create concerns as it drains across a landscape. There are practices that may be implemented by turfgrass professionals that target infiltration and storage of water to improve quality and help decrease the quantity of runoff.

Grassed swales (Photo 2) are a common practice that also help with reducing stormwater pollution. These shallow, open channel vegetated swales may be used along roadsides, in parking lots, residential subdivisions, commercial developments and on school campuses. An added benefit to incorporating grass swales is infrastructure costs may be reduced by eliminating the need for curb and gutter to traditional stormwater systems. Grass swales that use sod are less likely to encounter establishment issues as the sod provides a quick and dense cover.

Photo 2: Grassed Swale

An often-used practice is a rain garden system that is designed to capture, store, and drain stormwater within 48 hours of a rainfall. Rain gardens (Photo 3) are shallow depressions that are sized to catch the first inch of rainfall (where most of the pollutants are concentrated). The size of the garden depends on the impervious area it is draining, but a typical rule of thumb is 10–20% of the watershed. Rain gardens are typically suggested for residential or small commercial applications and may be sized from 60–1000 ft 2 . An infiltration test should be conducted to determine if an area is appropriate for the installation of a rain garden. If the soils drain in less than 36 hours, it is likely you’ll have success with a rain garden. Plants for a rain garden must be able to tolerate periods of drought and saturation. Species that tend to perform well include tickseed (Coreopsis spp.), coneflower (Echinacea pupurea), inkberry (Ilex glabra), and muhly grass (Muhlenbergia capillaris).

Photo 3: Rain Garden

Bioretention cells are similar to rain gardens in their function, but typically treat stormwater from a larger watershed and use a specialized media that allows for infiltration and stormwater pollutant removal. Bioretention cells have flexible siting requirements and can be installed within existing home or commercial landscapes, including yards, medians, cul-de-sacs, and other public spaces. They are not appropriate in areas with steep or unstable slopes due to the risk of erosion. Take a look at the medians or vegetated landscape features the next time you’re in a parking lot.

Do these parking lots allow for stormwater to flow into a treatment area (bioretention) or around them (raised curbs)? Several communities across Alabama have incorporated bioretention cells into large paved areas as a way to improve stormwater.

ATA members may consider keeping a vegetated buffer or streamside forest along waterways. Deeply rooted native vegetation acts as a filter, slowing stormwater and trapping pollutants before they get to our streams. Plant roots anchor the soil and help minimize erosion of property. Along streams, forest leaves provide shade to cool streams in the summer and serve as a source of food for stream critters in the winter after they fall. Not all green is good, however. Invasive species such as

Chinese privet (Ligustrum sinense) create dense monocultures that may not provide optimal wildlife habitat, limit native plant regeneration, and create unsightly thickets that are difficult to penetrate. To create or recreate a native streamside forest, you can choose to set aside ‘no-mow’ zones that are managed infrequently and recommend planting shrubs and trees such as river birch (Betula nigra), Virginia sweetspire (Itea virginica), and silky dogwood (Cornus amomum).

Resources

The Alabama Cooperative Extension System has several resources that may help with selecting water quality landscape features that are both attractive and functional. Check out resources in the Landscaping web resources to learn more about drought tolerant landscapes (https://www.aces.edu/blog/ topics/landscaping/drought-tolerantlandscapes-for-alabama/) and Alabama Smart Yards (https://www.aces.edu/ blog/topics/landscaping/smart-yardlandscapes/). Questions about how to take a soil test and where to send it? Visit the Extension web page with step by step directions (https://www.aces. edu/blog/topics/crop-production/homesoil-testing-taking-a-sample/).

If you’d like to dig deep into stormwater management practices used in green infrastructure, check out the Alabama Low Impact Development Handbook that is available for download (http://adem.alabama.gov/ programs/water/waterforms/LIDHand book.pdf). The handbook has chapters outlining planning, design, and maintenance for commonly used stormwater practices in urban and suburban areas.

Thinking about rainwater as a resource for landscaping and incorporating practices that can slow and infiltrate water before it reaches our local water ways can make a huge difference in the overall health of our drinking water supplies, recreational opportunities, and natural wonder of our state. For more information on Alabama’s water resources, ongoing projects, and special events visit www.aces.edu/aws. The Alabama Watershed Stewards program provides excellent information on how each of us may play a role in protecting and improving water resources.