IRRIGATION: PREVENTING RUNOFF

Here's a basic concept of a Florida Yard: Rain that falls in your yard should soak into your yard. After all, rainfall is an excellent source of water for your landscape, and reducing runoff will help protect waterways. Retaining rainfall long enough for it to percolate through the soil is particularly challenging in neighborhoods built before the late 1970s, when storm-water treatment ponds were not required. Please consider a few practical tips for reducing the amount of rainfall that runs off your yard.

Downspouts

If the roof of your home has rain gutters, make sure the downspouts are not aimed toward a paved surface. Turn downspouts into areas with plantings that will make better use of rainfall than letting it run down the driveway and into a storm drain. Be sure to choose plants for these areas that can adapt to having more water, and be sure water doesn't pool next to buildings.

Earth Shaping

Swales (small dips in the ground) and berms (raised earthen areas) can help divert runoff that is rushing from your yard. A bit of earth shaping can also be an attractive design element in your landscape. A berm-and-swale combination might be especially appropriate if your waterfront yard has a seawall. That, in combination with a maintenance-free zone of native plants, can make your yard more lagoon-friendly. Minor alterations to the lay of the land won't require permits or engineers, but any major earthwork should have the professional touch and will require regulatory review. Some cities and counties have natural resource departments that can provide advice on earth shaping. The USDA Natural Resources Conservation Service and local Soil and Water Conservation Districts also may provide assistance.

Rain Barrels & Cisterns

These ancient "technologies" are making a comeback as water shortages and environmental ethics lead homeowners to use rain that falls on their property. Large, plastic rain barrels are now available at home and garden stores and the Manatee County Water Department. The barrel looks much like a garbage can, but has a hole in the top where a roof downspout can fit snugly.

A valve near the bottom allows you to fill a watering can or connect a hose. These barrels are great for hand-watering, and they aren't mosquito-attracters as long as the downspout fits tightly. The barrel is not unsightly, and a four-foot shrub could easily shield it from view.

"Cistern" is really just a fancy word for rain barrel, but it implies a bit more engineering and greater storage capacity. Water is collected from the roof, filtered and stored in a container made of concrete, metal, wood, fiberglass or plastic. Water travels from the cistern upon demand by either gravity feed or pump action.

Porous Surfaces

Whenever possible, use bricks, gravel; turf block, mulch, pervious concrete or other porous materials for sidewalks, driveways or patios. These materials allow rainwater to seep into the ground, helping to filter pollutants and reducing the amount of runoff from your yard. In some cases they may even cost less to install than typical paving materials. Here's a comparison of surfaces for a 15-foot by 30-foot driveway. They are placed in order from most porous to least porous:


Recycled mulch costs $0.16-0.40 per square foot. It requires occasional replenishing. Cypress mulch not recommended because harvest depletes wetlands.
Washed shell costs $0.30 per square foot. It eventually compacts and hardens. It needs periodic additions and may alter soil pH.
Gravel costs $ 1.33 per square foot.
Pervious concrete costs $ 2.50 per square foot.
Shell rock (limestone) costs $0.94 per square foot. It hardens. It is prone to erosion. It may alter soil pH.
DOT-approved shell costs $0.25 per square foot. It may alter soil pH.
Concrete costs $ 1.50 per square foot.
Asphalt costs $ 1.17 per square foot.
For more information go to: http://edis.ifas.ufl.edu/EP079
A Guide to Environmentally Friendly Landscaping: Florida Yards and Neighborhoods Handbook
Allen Garner, John Stevely, Heidi Smith, Mary Hoppe, Tracy Floyd and Paul Hinchcliff. Environmental Horticulture Department, Florida Cooperative Extension Service, Institute of Agriculture Sciences, University of Florida. Publication date: May 2001.