NONPOINT SOURCE POLLUTION
Great strides have been made toward maintaining and restoring water quality throughout the United States since the formation of the EPA and the passage of the Clean Water Act. This has been accomplished through regulating point source pollution, such as smokestacks and sewage discharge. However, a more diffuse source of pollution, nonpoint source (NPS) pollution, threatens Alabama's ecosystems.Many of Alabama's water resources are especially susceptible to pollution due to our unique geology and climate. Many Alabamians obtain their drinking water from ground water supplies. Ground water often lies near the surface, covered by porous limestone and sandy soils, both of which allow water to infiltrate rapidly. Dissolved pollutants reach ground water through a process called leaching. These impurities affect the quality of our drinking water. Heavy rainfall is a major cause of leaching and stormwater runoff. Plants and animals that live in our lakes, streams, rivers, and estuaries are very sensitive to even small amounts of pollution.
Point source pollution: water pollution that results from water discharges into receiving waters from easily identifiable points; common point sources of pollution are discharges from factories and municipal sewage treatment plants. Nonpoint source (NPS) pollution: NPS pollution cannot be pinpointed to a single source. Over time, pollutants from our everyday activities accumulate on the land. Examples of NPS pollutants include pet feces, gasoline, fertilizer, pesticides, and even soil. NPS pollution is a problem when rainfall or heavy irrigation carries sediments and dissolved chemicals to waterways in stormwater runoff and by leaching or percolating through soil.
Stormwater runoff: water that runs off impervious or water-saturated surfaces, transporting sediments and dissolved chemicals into nearby waters.
A stormwater system is the collection of ditches, pipes, detention basins, and other conveyances that carry excess stormwater out of your neighborhood. In many communities across the state this water does not go to a treatment plant before it is released into local creeks and rivers. A healthy, properly maintained lawn helps treat stormwater by absorbing stormwater runoff. If stormwater runoff is not absorbed and contains unused nitrogen and phosphorus from fertilizers, when these chemicals enter natural waterways, they can fuel abundant algal blooms that smother natural vegetation, deplete oxygen, and possibly kill fish. These nutrients, if applied improperly, can cause invasive weeds to flourish, changing Alabama's natural plant communities. More alarming, potentially harmful substances, such as common household pesticides and fertilizers, can leach into our water supply. These materials damage aquatic life and harm people too. These substances that are washed from our neighborhood streets, walkways, and yards form NPS pollution.
These AYN Guidelines Will Help Reduce Nonpoint Sources of Pollution:
- Pick up after pets. This will help reduce bacterial and nutrient pollution entering stormdrain systems.
- Clean up oil spills and leaks on driveways. Spread cat litter over oil, sweep it up and then throw it in the trash.
- Sweep up grass clippings, fertilizer, and soil from driveways and streets and spread back onto the lawn. Remove trash from street gutters before it gets washed into stormdrains.
- Avoid over-fertilizing your lawn. Get a soil test to find out if your lawn needs phosphorus or not (many lawns do not need phosphorus). If results indicate that phosphorus is not needed, use a fertilizer formulation that does not contain phosphorus. Phosphorus is usually the most serious pollutant to lakes, rivers and streams contained in fertilizers that flush off lawns during significant rain events.
MAKING EVERY RAINDROP COUNT
One of the basic concepts of an Alabama-Friendly Yard is that rain that falls in your yard should soak into your yard. After all, rainfall is an excellent water source for your landscape, and reducing runoff protects waterways. Water that does not have the opportunity to be absorbed into the soil as it flows across lawns picks up fertilizers and pesticides and deposits them in our waterways. Retaining rainfall long enough for it to percolate through soil is challenging in neighborhoods built on compacted fill soils or steep slopes.Consider these Practical Tips for Reducing the Amount of Rainfall that Runs Off Your Yard:
- Direct downspouts and gutters to drain onto the lawn, plant beds or containment areas where rain will soak into the soil rather than run off the yard.
- Be sure that water doesn't pool next to buildings.
- If you decide to landscape the area where the downspouts drain, choose plants adapted to wet/dry extremes.
- Amend soil to increase percolation and absorbency. Consult your County Cooperative Extension Service agent as to how to amend your soil type.
GRASS-LINED SWALE
Consider incorporating attractive, functional earth shaping into your landscape to move water more efficiently. Create swales and berms to help catch, hold, and filter runoff that would otherwise rush from your yard. Decrease soil erosion by maintaining vegetative groundcovers or turf on areas under trees or on steep slopes. A densely growing turfgrass or ground cover is especially useful in capturing rainwater, filtering nutrients, recharging ground water, and reducing soil erosion. Consider converting ditches that are rock lined, concrete lined, or eroding into swales that are broad-bottomed and grass-lined.
Swale: a small dip in the ground. Berm: raised earthen areas.
Practical Tips for Directing Runoff in Your Yard:
- Minor alterations to the lay of the land won't require permits or experts, but any major earthwork should have a professional touch and will require regulatory review. Consult a landscape architect or stormwater engineer for design assistance.
- Check with your local Alabama DEP office before making any changes to shorelines of creeks, streams, lakes, or beach front.
Rain Barrels and cisterns are ancient technologies and they are making a comeback as water shortages prompt homeowners to save and use rain that falls on their properties. Large plastic rain barrels are now available at home and garden stores and on the Internet. For best results, choose one that is at least 42 gallons. Rain barrels typically tie into your home guttering system and reduce water pollution by reducing the amount of stormwater runoff. The barrel 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.
An overflow valve is needed near the top to remove excess water.
It can be directed back to the guttering system or to an adjacent rain garden. You can even connect a rain barrel to a swimming pool to replace water.
Need more than 42 to 55 gallons of water? You can link your rain barrels together simply by attaching them together.
A cistern also catches rain and has a greater storage capacity than a rain barrel. Water from a roof is collected, filtered, and stored in a container made of reinforced concrete, metal, fiberglass, or plastic. Although usually underground, cisterns may be placed at ground level or elevated on stands either outdoors or within buildings. Water travels from the cistern upon demand by either gravity feed or pump action.
A properly constructed cistern can be a source of supplemental water to provide for water needs other than human consumption. Currently in Alabama, water obtained from a cistern is only for non-potable uses, such as landscape watering. In other words: Do not drink it! Before building a cistern, check with local authorities to make sure that they are legal in your area.
Making a Rain Barrel
If you have gutters on your house, you may be able to collect 55 gallons of water during a ½ inch rain by connecting a downspout to a rain barrel. Many bulk type foodstuffs come in barrels. These FDA food-grade barrels make great rain barrels. If recycling a barrel, know what was stored in it. Do not use barrels that have held caustic or poisonous materials. Large plastic type trashcans also make great rain barrels. Important: Securely cover your rain barrel as a safety precaution for children and pets. Tools & Supplies:
Electric Drill (hand drill OK)
Plastic Drum (55 gal. best)
15/16 " Drill Bit
¾ " Spigot (PVC or Brass) with male threads
Sabre Saw (hand saw OK)
3" vinyl downspout elbow
PVC Cement for PVC spigot or Teflon tape for brass spigot
CaulkDirections:
- Drill 15/16 " hole about 6" to 8" from the bottom.
- Screw ¾ " spigot into hole; it should have snug fit.
- If using a PVC spigot, apply PVC cement to threads when it is about ¾ " tightened. Finish tightening. If using a brass spigot, apply Teflon tape to the threads and tighten.
- If connecting a gutter downspout, use a sabre saw to cut a hole in the lid to fit the spout. Use a 3" vinyl downspout elbow to connect the downspout to the barrel.
After inserting the down spout, caulk around the hole. No gutter downspout? Take off the lid of the drum or trashcan and cover the opening with a fine fiberglass screen to reduce mosquito breeding. Place the container where it will catch the water flowing off your roof.
- Elevate the barrel on 2 or 3 cement blocks to allow easy access to spigot (if you want more pressure, raise the barrel higher above the ground). Consider making a decorative stand.
- You may want to add a second spigot (or PVC overflow valve) at the top of the barrel so you can direct the overflow through a hose into a specific part of your yard or back into the gutter system.
- You can increase water storage by connecting rain barrels to each other using a 2" PVC connector to increase water storage.
Helpful Rain Barrel Hints:
- Barrels either have sealed lids or lids that can be removed.
- Barrels with sealed lids typically have two small round openings. These can be used for clean out.
- Barrels with removable lids have larger openings making cleaning out debris easier.
- Barrels that have flat bottoms are more stable.
- Corrugated plastic pipe can be used between the vinyl down spout adapter and the barrel to make removal and clean out easier.
- Barrels made of white plastic seem to disintegrate more quickly in the sun if not painted.
- When painting your rain barrel be sure to use a paint that is suitable for plastic surfaces.
CONTROLLING MOSQUITOES AND ALGAE
Rain barrels are great for hand watering, and they are not mosquito breeding grounds if the downspout fits tightly. If your barrel is open at the top, use Bacillus thuringiensis (Bt) products (often sold in a donut form) to kill mosquito larvae in an environmentally safe way. If you happen to have algae take root in your rain barrel, treat the water with submersible bacterial packets sold in pond supply stores. A rain barrel is not unsightly; however, a four-foot shrub can easily shield it from view.
RAIN CHAINS
Rain Chains are a beautiful and functional alternative to traditional downspouts. Rain Chains guide rainwater from the roof to the ground, and are typically handcrafted of copper that will gain a verdigris patina color as it ages. They produce soothing sounds as they guide rainwater from the rooftop to the ground. Rain Chains replace the traditional downspout on a typical household gutter system.
Rain Chains, otherwise known as 'kusari doi' in Japanese, are not a new idea. For hundreds of years, the Japanese have used the roofs of their homes to collect water, using chains to transport it into large barrels for household water usage. Rain Chains are easy to install by making a copper hook to rest in the gutter hole. The rain chain is hung from the hook.
Building a Rain Chain
- For an 8 to 9 foot Rain Chain, you will need about 40 feet of ¼ inch soft metal tubing for large rings and 15 feet for small rings. Cut the tubing with pruning shears or wire cutters, working the pieces back and forth until they separate. Save one foot of the tubing to be used later.
- Link the large rings together, and join each pair of large rings with a small ring using a pair of pliers.
- Remove your downspout. Shape the one foot piece of tubing, and then place it in the gap as shown. Secure the chain to the tubing using the top ring.
- Place a container (such as a rain barrel or large earthenware jar) underneath the chain to catch rainwater, and use the collected water to irrigate your garden.
Hints to Help Customize Your Rain Chain:
- You will need roughly 3.5 times as long a piece of metal tubing as you would like your finished chain.
- Metal tubing can be found in the plumbing department of home improvement stores.
- Large rings are about 3" or the diameter of a soup can. The small rings are roughly 1" or the diameter of a glass spice (seasoning) container.
- To create the large rings, wrap the tubing around a 3" piece of PVC (or similar sized tube); to create small rings, wrap the tubing around a 1-2" piece of PVC (or similar sized tube).
- Create a train of water quality friendly amenities! Have your Rain Chain flow into a rain barrel and the rain barrel overflow flow into a rain garden.
RAIN GARDENS
Rain gardens catch, filter, and hold stormwater. Rain gardens are simple gardens that are designed in pocket-like depressions to capture rain water from your roof top, driveway, and upland areas and then allow the rain water to slowly soak into the ground over a period of a day.If you are not collecting your roof runoff in a rain barrel, you can extend your gutter downspout to flow into a rain garden so that your roof runoff infiltrates and provides ground water recharge. Among their many benefits, rain gardens:
- Filter pollutants and reduce and slow down stormwater runoff.
- Can be designed to create stunning landscape features.
- Can include a variety of plants to attract birds, butterflies, and other wildlife.
- Do not breed mosquitoes because they drain within 48 hours.
Rain gardens are gardens that are typically landscaped with native plants. Though low in maintenance, they do require occasional weeding as well as watering in times of drought. They can be built by homeowners or professionally designed. They are placed in low-lying areas in your lawn and hold 6 to 18 inches of water for 24 to 48 hours. Their size depends on the area that will be draining to it.
How to Construct a Rain Garden
Materials:
Native plants
Garden hose
Level
Shovel or spade
Humus or other soil amendment
Measuring tape
- Measure the footprint of your house and determine how much of your rooftop area drains to the downspout you're using for your garden. For gutters with a downspout at each end, assume that half the water goes to each downspout. Be sure to measure the house footprint only.
- Locate the garden at least 10 feet away from your home's foundation.
- Maintain a minimum of 1% slope (1' drop/100') from the lawn down to the rain garden, or create a grassed swale to ensure the water flows from the roof to the garden, or use a downspout extension to direct the flow into the garden.
- Lay out the boundary of the garden with a garden hose.
- Dig a hole 6 to 8 inches deep across the entire surface of the garden.
- If the soil lacks organic matter, you can improve it by digging the hole 10 –12 inches deep and adding 4-6 inches of humus or other organic material.
- If necessary, create a berm on the lower side of the garden using the soil you have removed, or use a down spout extension or a grass swale to direct water into the rain garden.
Rain Garden sizing example:The Following AYN Guidelines Will Help You Make Your Rain Garden a Success:
30' x 30' house area
¼ of this area drains to one downspout
15' x 15' = 225 square feet
20% of 225 square feet = 45 square feet
30% of 225 square feet = 67.5 square feet
The rain garden area should be between 45 and 67.5 square feet depending on soil type (less 20% for sandier soils).
- Make sure the bottom of your rain garden is level.
- Rain gardens typically hold 6-18 inches of water.
- Before planting, test how the garden will hold water during a storm by letting water flow into the rain garden from a hose placed at the down spout. Make necessary adjustments.
- It may be helpful to draw out a planting plan before you install plants and mark the planting areas within the garden.
- Occasional weeding and pruning may be required.
- Occasional watering may be required if it doesn't rain.
- Leave the dead or dormant plants standing in the winter for seasonal interest.
Suggested Plants for Rain Gardens in Alabama
Choose drought tolerant plants that will not require much watering, but make sure they can withstand wet soils for 24 to 48 hours. Also take into consideration how much sun your rain garden will receive.
Stokes Aster (Stokesia laevis)
Black-eyed Susan (Rudbeckia hirta)
Purple Coneflower (Echinacea purpurea)For more information on Alabama rain gardens visit the ACES Water Quality Rain Garden site.
CONSTRUCTED WETLANDS AND RETENTION PONDS
Constructed wetlands and retention ponds are excavated basins that contain wetland vegetation to enhance pollutant removal from stormwater runoff. Stormwater enters a constructed wetland through a forebay where the larger solids settle out. The stormwater then passes through vegetation that acts to filter organic materials and soluble nutrients. Constructed wetlands provide an alternative drainage point for untreated stormwater instead of placing it directly into a stream. Important: Existing natural wetlands should never be destroyed to construct another wetland habitat for stormwater treatment.Click here for pond building information.
Another way to filter runoff is by installing a series of swales and channels, followed by a small retention pond as a final collection point for runoff. A retention pond is designed to hold a specific amount of water indefinitely. Usually the pond is designed to have drainage leading to another location when the water level gets above the pond capacity, but still maintains a certain capacity. A pond provides a natural filter for potential waterway pollutants. Vegetative swales and channels act as active filtration systems for pollutants, and the settling action in the pond itself serves as another way to remove pollutants. A well-built pond that supports plant life can significantly improve the quality of water draining into Alabama's waterways.
Helpful Hints:
Constructed wetlands and retention ponds are considered major earthwork, require permits, and must be designed to regulations. Contact a landscape architect or stormwater engineer to help you design your pond to meet regulations.
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