What Is Nonpoint Source Pollution?
Nonpoint source (NPS) pollution is pollution that originates from diverse sources and is difficult to measure directly. Categories of NPS pollution include agriculture, silviculture (forestry related activities), construction, urban run-off, resource extraction, land disposal, hydromodification and saltwater intrusion. Sewage discharge and runoff from camps and homes is also considered nonpoint source pollution.

Where Does it Come From?
Every time it rains, sediments, nutrients, bacteria, heavy metals, pesticides, oil, grease, and other pollutants are washed from streets, parking lots, lawns, farms, logging areas, construction sites, parks, and camps into our rivers, bayous, lakes, and estuaries. Excess rain that cannot be absorbed into the soil becomes storm water run-off which washes pollutants into water bodies.

Urban Runoff
Past concerns with urban runoff have primarily dealt with the prevention of localized flooding. Only recently has urban runoff been considered as a significant contributor to the degradation of the quality of receiving waters.

Urban nonpoint source pollution is the result of precipitation washing the surfaces of urbanized areas. As precipitation falls on urban areas it picks up contaminants from the air, littered and dirtied streets and sidewalks, petroleum residues from automobiles, exhaust products, heavy metals and tar residuals from the roads, chemicals applied for fertilization, weed and insect control, and sediments from construction sites. The dumping of chemicals such as used motor oil and antifreeze into storm sewers is another source of urban NPS pollution. Illegal hookups of storm drains to sanitary sewers can result in increased volumes of flow to waste water treatment plants causing more frequent overflows of sewage into receiving waters.

A significant amount of NPS pollution results from poor landscaping techniques. As a result, pollution prevention opportunities abound in the area of landscaping. Integrating P2 into landscaping can offset the negative impacts of pesticides and herbicides on the environment and reduce NPS pollution. P2 activities should be incorporated into landscaping beginning with the design phase and continuing throughout the life of the yard/garden.

Urban NPS pollution is not limited only to large communities. Rural areas where small communities exist contribute to urban NPS pollution as well. For example in waters of Louisiana identified by the 1990 Louisiana Water Quality Inventory Report (Section 305 [b]) as not fully supporting their designated uses, urban NPS pollution attributed to 1.4% of major impacted rivers, 10.4% of moderately impacted rivers, 12.9% of moderately impacted lakes, and 12.3% of moderately impacted estuaries.

In the design phase it is important to begin by shaping the ground and selecting plantings to reduce pollution, control erosion, and enhance aesthetics and wildlife habitat. The wise use of pesticides and herbicides to grow plants and control pests during the growth stage is especially critical. Effectively maintaining the landscaping is the final stage of a process that makes it possible to have beautiful green areas that do not harm the environment, and particularly our local waterways.

Best Management Practices
The term "best management practices" (BMPs) describes any practice or routine procedure designed to either reduce pollutants that can be picked up by run-off or reduce the amount of pollutants in the run-off before it gets to a body of water for contamination. BMPs are designed to reduce pollutants such as sediments, nutrients, heavy metals, bacteria, pesticides, or any form of stormwater pollutants in run-off.

Examples include pollution source controls (proper fertilizer application techniques), solid waste collection (proper storage containers) and disposal (proper leaf and household hazardous waste disposal), run-off collection and distribution (detention ponds and landscaping), and discharge treatment (constructed wetlands).

Other types of source control activities involve local government initiatives such as creation and enforcement of litter laws, penalties for used motor oil dumping, zoning laws and enforcement for landuse, and requirements for proper source controls to be included in construction of new development (landscaping parking lots, grass buffer strips and detention ponds).

Green landscaping is utilizing P2 principles to reduce the detrimental affects of landscaping on the environment. Green landscaping techniques can be used by amateurs and professionals alike

P2 ACTIVITIES

• Common storm water pollutants
• Leading sources of storm water pollution
• Indicators of storm water pollution
• Preventing storm water pollution
• DCIA Minimization

7 Principles of Green Landscaping

According to the Province of Manitoba, there are seven principles of Green Landscaping. Green landscaping is utilizing P2 principles to reduce the detrimental effects of landscaping on the environment.

1.                  Planning and Design

Consider site characteristics such as drainage, sun, shade, wind, slopes, noise, and privacy

Determine your needs and wants - garden, entertainment, service, and play areas

2.                  Soil

Most plants grow best in loamy soil that drains well and contains organic material

Check with your local Master Gardener program for information about soil analysis

3.                  Reduce Turf Area

Decide how much lawn area you really want.? Use lawn as an accent, not the focal point.? Using low maintenance plants (particularly native plants) and decorative garden material (such as rock, stones, potted plants) can enhance a yard without having to rely on lawns.

4.                  Irrigation

If you do have to irrigate, water deeply, but not often. The larger the water drop size, the less evaporation will occur.? Apply the water as close to the ground as possible.? If water begins to pond while watering, water for 15 minute intervals until the needed water has been applied. Minimize your need for irrigation.? Group plants according to their water needs, and according to the attributes of the area of your yard.? Know your yard!? If you have one area that is extremely hot and dry, use drought tolerant species.? Likewise, if you have an area that is always damp or wet, use plants suited for that environment.

5.                  Mulches

Mulching assists soil in retaining moisture, reducing weed growth and preventing erosion. Options include: straw, grass clippings, leaves, newspaper, wood chips, pine cones, compost, and peat moss. Apply the mulch 3 to 4 inches thick, ensuring that the mulch does not touch the stalks or trunks of plants.

6.                  Plant Selection

Choose plants that are appropriate for the area of your yard (sun versus shade, dry versus wet, etc). Know what direction your yard faces (north, south, east or west) and chose appropriate plants and place them according to where the sun is most intense. Consider size, color, and texture of the plants.? A variety of low maintenance, drought tolerant plants can add variety and interest to your yard. Plants native to your area are already adapted to the climate.? In addition, may are perennial or self-seeding, reducing future costs for new plants. Many native plants will also support indigenous animals, such as butterflies and birds which provide natural pest control.

7.                  Maintenance

Although low-water landscaping typically results in low maintenance, there will still be some maintenance task to be performed.? These include:

• Adding mulch yearly
• Amending flow and vegetable beds
• Pruning trees and shrubs
• Dividing and transplant perennials as required
• Cutting down perennial tops
• Ensuring nutrients in soil are adequate for area plants
• Weeded as needed

Naturescaping
Landscaping with native plants (wildflowers, gasses, cacti, etc.) improves the environment. Natural landscaping brings a taste of wilderness to urban, suburban and corporate settings by attracting a variety of birds, butterflies, and other animals. Once established native plants do not need fertilizers, herbicides, pesticides, or watering, thus benefiting the environment and reducing maintenance costs. A native landscape typically does not need to be mowed like a conventional lawn. This in turn reduces the demand for non-renewable resources and improves air and water quality.

According to the EPA, native landscaping practices can help improve air quality locally, regionally, and globally. Locally, smog (ground level ozone) and air toxics can be drastically reduced by the virtual elimination of lawn maintenance equipment (lawn mowers, weed edgers, leaf blowers, etc.) fueled by gasoline, electricity or batteries. All of these fuel types are associated with the emissions of the following air pollutants: carbon monoxide (CO), carbon dioxide (CO2), nitrous oxides (NOx), sulfur dioxide (SO2), VOCs (volatile organic compounds) and air toxics such as benzene. Gasoline lawn and garden equipment, on average, produces 5% of ozone-forming VOCs in areas with smog problems. This equipment also emits toxics and particulates.

Regionally, the NOx and SO2 released from lawn maintenance equipment react with water in the atmosphere to form acid rain. Globally, native landscaping helps combat global warming in two ways. Carbon dioxide (CO2) is a major greenhouse gas and by reducing the use of lawn maintenance equipment, the associated CO2 emissions are also reduced. Native plants help reduce the amount of CO2 in the atmosphere by taking in CO2 and storing the carbon in the body of the plants, roots and soil. Native plants work much better than traditional mowed grass as a carbon sink due to their extensive root systems and increased ability to retain and store water.

In conventional landscaping, pesticides are often wrongly applied at times when target insects are not vulnerable. Overuse and inappropriate use often kill beneficial insects and other wildlife. Less than 10% of all insects are harmful to plants. Pesticides have the potential to cause serious human health problems when not handled properly or applied according to the label directions. By eliminating or minimizing the use of pesticides and fertilizers these pollutants will not run-off into streams, lakes, bays, and reservoirs. This improves the quality of the water and the aquatic life in it. In healthy water systems, natural controls, such as fish, frogs, and snails will help keep insect populations under control and reduce algae buildup.

Naturescaping is a way of putting native plants and beneficial wildlife habitat back into yards or communities. Native plants are the foundation of naturescaping. The plants that evolved in a region are well adapted to the region’s climate and naturally resistant to local pests and diseases. Once established, natives can often survive on rainwater alone. Naturescaping areas can include replacing some lawn area with a wildflower meadow, hummingbird and butterfly garden, plants and trees selected for seeds, fruit, and nectar, and nesting boxes.

When creating a naturescape, it is important to include four elements: food, water, shelter, and adequate space. When creating a naturescape in a yard or community, keep in mind these steps:

• Visit “wild” places and naturescaped sites and imagine how these landscapes would fit into your yard or community.
• Educate yourself and your community. Learn about native plants and basic design and care concepts. You can attend workshops and read plant and design books.
• When you are ready to develop a site plan, choose a small viewable site. When planning, consider maintenance water, gardening, and access to feeders. Know the existing conditions of the area: shade/sun, wet/dry, wind patterns, drainage, existing plants and critters. Once you develop a plan and get any necessary permits, you are ready to gather your material and begin.

The Environmental Protection Agency (www.epa.gov) has many programs designed to encourage and support planting with native plants.

Once a site or yard is developed, landscaping and maintenance of lawns and gardens also offer many pollution prevention opportunities.

General Landscaping Tips

• Protect stockpiles and materials from wind and rain by storing them under tarps or secured plastic sheeting.
• Schedule grading and excavation projects for dry weather.
• Prevent erosion by planting fast-growing annual and perennial grasses. These will shield and bind the soil.
• Store pesticides, fertilizers, and other chemicals indoors or in a shed or storage cabinet.
• Use temporary check dams or ditches to divert runoff away from storm drains.
• Protect storm drains with sandbags or other sediment controls.
• Revegetation is an excellent form of erosion control for any site.

Lawn Tips

• Ensure grass is a drought resistant variety.
• Cut grass 7.5 to 10 cm (3 to 4 inches) - grass this length requires less water because roots, new growth and soil are shaded.
• Water the garden in the morning when there is little wind to minimize evaporation.
• Buy a timer for your outside faucet or use a kitchen timer as a reminder to turn water off.? Better yet - install a sprinkler system with an automatic timer.
• Use a soil moisture indicator for your lawn, or measure rain and sprinkler water in a container.? Three centimeters (one inch) of water per week is usually enough.
• Aerate your lawn regularly.
• Use a watering can with water from your rain barrel for plants that need extra water.? In low rain areas, consider re-using house water (from sink or bathtub) to water plants that need extra water.
• Encourage children to use water toys and a splash pool, rather than a hose or a sprinkler, to keep cool.? Use the water from the pool for your garden.

 

Fertilizing
Fertilizing can present serious pollution problems for homeowners and businesses. Suggestions for fertilizing in an environmentally-friendly way include:

• Use organic or non-toxic fertilizers.
• Do not over-fertilize and do not fertilize near ditches, streams, or other bodies of water.
• Ensure that any soil additives are consistent with soil analysis.
• Use compost to amend and enrich soil in order to reduce the amount of fertilizer needed.
• Fertilize turf moderately with slow release fertilizers only as needed.

Landscaping/Garden Maintenance

• Use pesticides sparingly, according to the instructions on the label. Dispose of unused pesticides as hazardous waste.
• Store pesticides, fertilizers, and other chemicals in a covered area to prevent runoff.
• Do not over-water. Conserve water by using irrigation practices such as drip irrigation, soaker hoses, or micro-spray systems.
• Collect lawn and garden clippings, pruning waste, and tree trimmings. Chip if necessary and compost.
• In communities with curbside pick-up of yard waste, place clippings and pruning waste at the curb in approved bags or containers. (Or take to a landfill that composts yard waste).
• Do not blow or rake leaves into the street, gutter, or storm drains.
• Space plants properly (avoid over-planting which results in excess pruning, possible plant removal and generation of excessive green waste).
• Do not use invasive plant species (e.g. scotch, French or Spanish broom).
• Use plants that will not grow too large for their space and use trees and shrubs that do not require frequent shearing.
• Turf Management – grasscycle, coordinate irrigation and mowing schedules to avoid mowing wet grass. Mow over light leaf fall and use the mixture as mulch. Topdress turf with compost made from yard/landscape waste material or use slow release fertilizers such as sulfur or polymer coated urea
• Prune conservatively to maintain shrub/tree health, natural form/shape and reduce green waste generation.
• Allow leaves to stay on the ground under the tree drip line or use as mulch (in areas where leaves will not enter stormwater drains).

Pool/Fountain/Spa Maintenance
When it’s time to drain a pool, spa, or fountain, please be sure to call your local wastewater treatment plant before you start for further guidance on flow rate restrictions, backflow prevention, and handling special cleaning waste (such as acid wash). Discharge flows should be kept to the low levels typically possible through a garden hose. Higher flow rates may be prohibited by local ordinance.

• Never discharge pool or spa water to a street or storm drain.
• Chlorinated water may be discharged to the sanitary sewer (if allowed by the local sewage treatment authority) by running a hose to a utility sink or sewer pipe cleanout junction.
• If possible, when emptying a pool or spa let chlorine dissipate for 5 to 7 days. Then recycle/reuse water by draining it gradually onto a landscaped area, or drain the dechlorinated water to a storm drain.
• Do not use copper-based algaecides. Control algae with chlorine or other alternatives to copper-based pool chemicals (such as sodium bromide). Copper is harmful to aquatic life and cannot be completely removed by the sewage treatment plant.
• Never clean a filter in the street or near a storm drain. Rinse cartridge and diatomaceous earth filters onto a dirt area, and spade filter residue into soil. Dispose of spent diatomaceous earth in the garbage.
• If there is not suitable dirt area, call your local wastewater treatment plant for instructions on discharging filter backwash or rinsewater to the sanitary sewer.

Xeriscaping
Alternative landscaping techniques such as xeriscaping can also be used. Xeriscaping is considered to be a viable alternative to the high water requirements of typical landscaping. It is a form of landscaping that conserves water and protects the environment. Xeriscaping does not result in landscaping with cactus and rock gardens. Rather, cool, green landscapes can be used when they are maintained with water-efficient practices. The main benefit of xeriscaping is that it reduces water use (TAMU, 1996). Xeriscaping incorporates seven basic principles that reduce water use (NYDEP, 1997):

• Planning and design: consider drainage, light, and soil conditions; desired maintenance level; which existing plants will remain; plant and color preferences; and budget.
• Soil improvement: mix peat moss or compost into soil before planting to help the soil retain water. Use terraces and retaining walls to reduce water run-off from sloped yards.
• Appropriate plant selection: choose low-water-using flowers, trees, shrubs, and groundcovers. Many of these plants need watering only in the first year.
• Practical lawns: limit the amount of grass area. Plant groundcovers or add hard surface areas like decks, patios, or walkways. If replanting lawns, use drought-tolerant grass seed mixes.
• Efficient irrigation: install drip or trickle irrigation systems, as they use water efficiently.
• Effective use of mulches: use a 3-inch deep layer of mulches such as pine needles or shredded leaves or bark. This keeps soil moist, prevents erosion, and smothers weeds.
• Appropriate maintenance: properly timed fertilizing, weeding, pest control, and pruning will preserve the beauty of the landscape and its water efficiency.

Trees, in particular, can help prevent pollution. They can cleanse and cool the air, act as a buffer for wind and noise, protect water quality, and prevent soil erosion. Two articles, “Selecting, Planting & Pruning Trees” by Matt Grubisich (Texas Forest Service) and “Oak Wilt” from Keep Midland Beautiful, are especially informative.

Selecting, Planting & Pruning
Oak Wilt

Pest Control
Pest control measures present particular pollution challenges. The EPA estimates that nearly 70 million pounds of active pesticide ingredients are applied to urban lawns each year. The presence of pesticides in storm water runoff has a direct impact on the health of aquatic organisms and can present a threat to humans through contamination of drinking water supplies. The major source of pesticides in urban streams is home application of products designed to kill insects and weeds in the lawn and garden.

Integrated Pest Management (IPM) is an effective and environmentally sensitive approach to pest management that relies on a combination of common-sense practices. IPM programs use current, comprehensive information on the life cycles of pests and their interaction with the environment. This information, in combination with available pest control methods, is used to manage pest damage by the most economical means, and with the least possible hazard to people, property, and the environment.

The IPM approach can be applied to both agricultural and nonagricultural settings, such as the home, garden, and workplace. IPM takes advantage of all appropriate pest management options, including -- but not limited to -- the judicious use of pesticides. In contrast, organic food production applies many of the same concepts as IPM but limits the use of pesticides to those that are produced from natural sources instead of synthetic chemicals.

IPM is not a single pest control method but, rather, a series of pest management evaluations, decisions, and controls. Integrated pest management is a sustainable approach to managing pests by combining biological, cultural, physical, and chemical tools. Municipalities can encourage homeowners to practice IPM and train/encourage municipal maintenance crews to use these techniques for managing public green areas. There are many methods and types of integrated pest management, including the following:

• Mulching can be used to prevent weeds where turf is absent, fencing installed to keep rodents out, and netting used to keep birds and insects away from leaves and fruit.
• Visible insects can be removed by hand (with gloves or tweezers) and placed in soapy water or vegetable oil. Insects also can be sprayed off the plant with water or in some cases vacuumed off of larger plants.
• Store-bought traps, such as species-specific, pheromone-based traps or colored sticky cards, can be used.
• Sprinkling the ground surface with abrasive diatomaceous earth can prevent infestations by soft-bodied insects and slugs. Slugs also can be trapped in small cups filled with beer that are set in the ground so the slugs can get in easily.
• In cases where microscopic parasites, such as bacteria and fungi, are causing damage to plants, the affected plant material can be removed and disposed of. (Pruning equipment should be disinfected with bleach to prevent spreading the disease organism.)
• Small mammals and birds can be excluded using fences, netting, and tree trunk guards.
• Beneficial organisms, such as bats, birds, green lacewings, ladybugs, praying mantis, ground beetles, parasitic nematodes, trichogramma wasps, seedhead weevils, and spiders that prey on detrimental pest species can be promoted.
• Reduce potential pest problems by planting a variety of species rather than a monoculture.
• Use climate appropriate, hardy, pest-resistant plants to avoid fertilizers and chemical pest controls. Consult the WUCOLS (Waste Use Classifications of Landscape Species) list to determine which drought-tolerant species grow best in your area.
• Limit habitat and breeding areas for rodents, mosquitoes, and flies (eliminate ivy, wood and debris piles, animal waste, fallen fruit, standing water).
• Use proper pruning techniques and prune conservatively.
• Apply pesticides on an as-needed basis (rather than calendar spraying) only after alternative control measures have been considered.
• Avoid these problematic pesticides:
  • Those that are highly persistent or highly toxic
  • Broad-spectrum insecticides (e.g., chlorpynifos, diazinon, pyrethroids)
  • Herbicides with clopyralids or picloram which persist in compost

Articles that will assist in pest control programs include:
Pollution Prevention Fact Sheets: Pest Control
Getting Smarter About Pests

Storm Water Protection
A final area of concern in landscaping is water contamination. Storm water from urban runoff and sewers is one of the leading causes of pollution in rivers and lakes. In fields and forests, most rain is absorbed by the soil or is taken up by plants and trees. However, developed areas contain many impermeable surfaces like roofs, parking lots and streets. In developed areas, rainwater often travels over paved areas, settles in gutters and ditches, and flows through concrete storm drains. Rainwater that flows overland is called storm water or storm water runoff.

Storm water can quickly become polluted by chemicals, fertilizers, pesticides, and litter it picks up while traveling overland. Even small amounts of pollutants that accumulate on roads, parking lots, and sidewalks are quickly transported into nearby streams and rivers, causing major water quality problems. Identifying sources of storm water pollution and keeping them off the ground (away from storm drains or roadside ditches) is the best and most economical way to keep storm water clean.

Common storm water pollutants are:

• Oil and grease - Oil from vehicles storage tanks and machinery, and grease from kitchen waste and engine lubricants can be carried by storm water into streams. Oil and grease float on the water's surface and block sunlight needed by underwater fish and plants. Oil and grease can also damage stream habitat and sensitive spawning areas when they cling to sand and gravel particles that settle to the bottom of streambeds.
• Heavy metals - Heavy metals like lead, zinc, and mercury, are ingredients in many commonly used products like batteries, fuels, paints, pesticides, and cleaners (e.g. algaecides). They can also be found in industrial-strength materials like rubber. When these products are spilled or improperly disposed of and when materials containing heavy metals break down, they leave behind pollutants that can be readily transported into streams by storm water. Heavy metals can be toxic to fish and other aquatic life in streams.
• Nutrients - Nutrients like phosphorus and nitrogen are transported into streams when storm water picks up fertilizer and animal manure residues on the ground. When excessive amounts of nutrients end up in water bodies, they accelerate algae growth and cause eutrophication, which disrupts life in ponds and streams.
• Chemicals - Toxic chemicals in fuels, paints, cleaning products, and pesticides (used at work and home) can harm not only users but also water quality and aquatic life when they are improperly handled. Chemicals, especially organic chemicals, have a wide range of toxic effects on fish and aquatic life, including causing tumors and skin lesions and disrupting reproductive functions.
• Mud and sediment - These are readily carried by storm and flood waters, causing excessive buildup (commonly called sedimentation). When storm water flows across construction sites and unplanted fields, it picks up loose dirt, creating mud, which is quickly carried into streams where it causes sedimentation pollution. When too much sediment accumulates on streambeds, it damages fish-spawning areas, alters habitat where bottom-dwelling organisms live and reproduce, and interferes with fish migration. In addition, dirt and sand often pick up oil and grease in their path, introducing additional chemical contaminants that are toxic to fish and other aquatic organisms.
• Litter - Debris that overflows from trash cans and litter thrown onto the ground are readily carried by storm water into streams and rivers where they harm fish and aquatic life, hinder sunlight penetration, and interfere with fish movement and migration.
• Abnormal pH - When storm water mixes with chemicals or chemical products that are acidic or alkaline, the pH of the water is changed. When acid rain and other forms of acid precipitation collect in streams and ponds, it also alters the pH. Acidic or alkaline conditions in streams harms fish, especially sensitive juvenile fish and other organisms.
• Coliform bacteria - At high levels, naturally occurring coliform bacteria from human and animal wastes can contaminate water. Picking up and disposing of pet feces helps prevent bacteria pollution and eutrophication in streams.

Leading sources of storm water pollution are:

• Refueling, engine repair, equipment washing, and painting activities, especially when these activities occur outdoors or when wastewater is released outside.
• Roads, parking lots, and other paved surfaces where fluids have leaked, hazardous materials have spilled, or litter, particles, and sediments have accumulated.
• Outdoor vehicle, equipment, and material storage that exposes spilled, leaked, and overflowing fluids and chemicals to rain and storm water runoff.
• Outdoor cleaning and maintenance activities like power washing, sandblasting, and car washing that produce large volumes of wastewater.
• Construction activities that excavate land, exposing loose dirt and sand.
• Farming and agricultural activities that add fertilizer, pesticide, nutrient, and sediment pollutants to the watershed.
• Commercial properties and residential lawns where fertilizers and pesticides are used.
• Landfills, trash storage areas, and waste handling and disposal activities when improperly managed.

The following are indicators of storm water pollution:

• An oil sheen on the water's surface.
• Roads, parking lots, and other paved surfaces where fluids have leaked, hazardous materials have spilled, or litter, particles, and sediments have accumulated.
• Stains on and around the ground and storm drains.
• Unusual discoloration of grass, plants, and vegetation.
• Distressed vegetation and plants .
• Poorly maintained, corroded, or damaged drums and machinery.
• Commercial properties and residential lawns where fertilizers and pesticides are used.
• Uncovered and improperly maintained storage areas and dumpsters.

Preventing Storm Water Pollution
There are both simple and complex ways to prevent and control storm water pollution. Individual efforts, like those below, may seem trivial, but collectively add up to considerable storm water P2.

• Dispose of litter properly.
• Keep storm drains clear of debris, dirt, sand, silt, and wastes.
• Catch fluids and recycle or properly dispose of them when changing car oils, antifreeze, and other fluids. Participate in the facility's oil recycling program.
• Wash cars or other greasy equipment at facilities, such as commercial car washes, that collect wastewater and discharge it into a sanitary sewer where detergent and oily pollutants can be removed at sewage treatment plants
• Reduce or eliminate chemical pesticides and fertilizers for landscaping and lawns.
• Plant around or pave areas prone to erosion to reduce the chance that loose dirt, soil, and sand will be carried away by storm water runoff.

DCIA Minimization
Practices used to minimize DCIA include:

• Disconnecting roofs from street drainage systems. This can be achieved by installing a rainwater tank, an infiltration device or allowing roof water to discharge via various landscaping measures.
• Allowing stormwater from paved surfaces to discharge to pervious areas with landscaping.

The benefits of reducing DCIAs are:

• Reduced stormwater peak discharges and volumes.
• Improved water quality by reduced filtration through vegetation and reduced erosion.
• Maintain groundwater recharge by maximizing infiltration.

A strategy to minimize the environmental impact of urban allotments and the requirement for street drainage infrastructure will include landscaping measures minimization of DCIAs. Landscaping measures include the use of vegetated filter strips, contour banks, mulching, trees and shrubs. The benefits of landscaping measures include:

• Reduced stormwater peak discharges and volumes.
• Increased infiltration.
• Retention of native vegetation.
• Reduced erosion and sedimentation.
• Retention of soil moisture.

Stormwater quality
The quality of stormwater discharging from an urban allotment using a landscaping and reduction of DCIA strategy will depend on the combination of measures used.