Many human activities unintentionally add nitrogen and phosphorus or other pollutants to surface waters. Over many decades, urban development, farming, industry and man-made pollutants — such as partially treated sewage from our homes and businesses — have been pumped into waterways for disposal, causing a decline in the health of our rivers and streams.
Stormwater runoff has also contributed to the decline of waterways. Storm water or excessive irrigation water running over our lawns, sidewalks, streets and parking lots take fertilizers and pesticides, motor oil and heavy metals into waterways. In fact, storm water contributes 80 to 95 percent of the heavy metals — copper, lead and cadmium — that enter Florida waters.
Before Florida was developed, the state had numerous wetlands. Wetlands, also known as swamps or marshes, are important ecological systems that help filter out pollutants and sediments collected by storm water as it runs over the land’s surfaces before reaching our natural waterways.
Water pollution comes from many sources. Following is a summary of some of the major causes.
Wastewater from central sewers
Every day wastewater from sinks, dishwashers, clothes washers and toilets flows into sewer pipes to a treatment plant. Oftentimes, this partially treated sewage leaves the treatment plant and is discharged to a waterway.
This wastewater can be treated to remove harmful organisms and substances, and made safe for irrigation and nonpotable (nondrinking) water needs. The use of this “reclaimed” water is an environmentally responsible alternative to disposing of the treated waste water in surface waters. Likewise, practicing water conservation can help reduce the amount of water that must be disposed of from our homes and businesses.
Wastewater from septic tanks
In Florida, approximately 33 percent of the population is served by an estimated 2.5 million on-site sewage treatment and disposal systems (OSTDS).
A septic tank system consists of a large, watertight tank that receives wastewater from the home plumbing system. The tank is followed by an underground drainfield consisting of a network of perforated pipe or chambers for distributing partially treated water from the septic tank to the soil for final treatment and disposal.
A septic system that is not properly located, designed, installed or maintained can allow liquid wastes to pollute nearby surface waters and groundwater, according to the Florida Department of Health. Contaminants can travel long distances in some soils. Therefore, drinking water wells should be located at least 75 feet from any part of a septic tank system.
Septic tank systems can fail when the drainfield does not dispose of sewage as rapidly as it is being added to the system. Thus, improvements that reduce the amount of incoming water or improve the quality of wastewater passing through the system will increase the system’s longevity.
The Florida Department of Health Bureau of Onsite Sewage Programs and county environmental health units regulate the use of septic tanks in Florida. In addition, the U.S. Environmental Protection Agency provides guidance, technical information, management guidelines, and a variety of other information to help individuals manage their septic systems.
Storm water from our roads and drainage ditches
Stormwater runoff — water that runs off or flows over the ground after a rainstorm — picks up debris, chemicals, soil, yard waste, fertilizer, motor oil and other pollutants. Storm water is carried into local retention (stormwater) ponds or directly into local waterways through storm drains that eventually reach water bodies. This water is not treated in a water treatment plant.
Sometimes this water is partially treated through a stormwater pond. Stormwater ponds provide temporary storage of stormwater runoff and capture a variety of pollutants that would otherwise work their way downhill to waterways and wetlands.
In 1982 the Florida Legislature passed legislation requiring treatment of storm water and reducing stormwater runoff. Since then, all new developments have been required to use best management practices (BMPs), such as retention or detention ponds, detention ponds with filtration, and swales to minimize runoff during construction and to treat storm water after construction.
The responsibility for permitting stormwater management systems rests with water management districts and, in some cases, the Florida Department of Environmental Protection. After developers complete construction of permitted systems in residential areas, the permit and the legal responsibility for maintaining these systems are typically passed on to a homeowners association.
Fertilizer and pesticides from our lawns
Nitrogen pollution comes from many sources, including from the fertilizers used on lawns and in landscaping. This nitrate-rich water makes its way to surface waters as runoff during rainfall or over-irrigation, or it may drain slowly from the soil over time.
Algal blooms in water bodies can be attributed to nitrogen pollution.
Using fertilizers only when lawns show a particular nutrient deficiency and using chemicals responsibly can benefit our waterways.
Discharges from farmlands
For generations, thousands of acres of farmland have been cultivated throughout Florida. In many cases, nutrient-rich water from farm fields has drained or been pumped into natural water bodies without treatment, impacting water quality. This overabundance of nutrients encourages algal blooms that deplete oxygen from the water and block sunlight from reaching underwater vegetation, critical to fish and wildlife habitats.
The St. Johns River Water Management District has worked with agricultural interests for more than two decades to restore the health of the St. Johns River. For example, the District’s work in the tri-county agricultural area (TCAA) of Putnam, St. Johns and Flagler counties has involved the development of controlled-release fertilizers and new best management practices (BMPs) to reduce phosphorus and nitrogen loading to the St. Johns River. At the river’s headwaters in Brevard and Indian River counties, the District has worked with farmers to treat water from citrus growing areas and to make that water available for freeze protection and irrigation as needed.
Sediment from construction sites
Sediments from soil at construction sites can wash into waterways, which can create problems for aquatic life. Turbidity — cloudy water caused by suspended matter — reduces the amount of sunlight able to reach submersed plants. Siltation — the settling out of the sand, silt and other matter suspended in the water onto the bottom of the water body — destroys submersed grass beds and other bottom-dwelling plants and animals, in addition to impacting drainage and navigation.
Since 1982, all new developments have been required to use BMPs to minimize erosion during construction and may include requiring stormwater treatment facilities.
Pollution of surface waters is generally categorized as point source or nonpoint source. With point source pollution, the cause of the problem can be traced to a single source — for example, a pipe or culvert discharging wastewater from a factory. Some industrial and sewage treatment plants connect directly to a water body and create point source pollution, but not all pipes create point source pollution.
In the past, pollution from industrial and domestic point sources was common. However, stronger regulations, newer technologies and more advanced treatment of wastes have reduced pollution. These sources are regulated by federal, state and local laws. Within Florida, the Florida Department of Environmental Protection (DEP) and state’s water management districts work to prevent many kinds of water pollution, restore natural systems already damaged by contaminants, and educate the public about preventing water pollution.
Posted on 11-18-2011