A watershed is all the land area that drains into a stream, river, lake or other body of water. Stormwater runoff – rainfall that does not soak into the ground, but instead flows over the land into these surface waters – is important to replenish our water supply, but can also harm our watersheds if pollutants are collected along the way.
Stormwater runoff occurs naturally, but as development and the amount of impervious surface such as rooftops, roads and parking lots increase in a watershed, the natural capacity of the soil and vegetation to filter and take up rainfall decreases, and more rainfall becomes stormwater runoff. This can produce negative impacts such as erosion, flooding and contamination of our water.
Stormwater pollution can make monitoring and treatment of our drinking water more difficult and costly, especially in metropolitan North Georgia where almost all of our drinking water comes from surface water. In addition, stormwater can affect the health of the aquatic ecosystem and make streams, rivers and lakes unsafe for swimming, fishing or other recreational uses.
How Does Wastewater Pollution Occur?
Wastewater is water that has been used by homes, industry and business that must be treated before it is released back into the environment. Wastewater is either transported by a sewer system to a wastewater treatment plant, or it is treated onsite within a self-contained septic system.
The Metro Water District has 303 wastewater treatment facilities, including 92 publically owned and 211 privately owned facilities. These facilities clean water that is often contaminated with human waste, oils, soaps and chemicals through a staged process. The steps taken to remove organic matter, contaminants, bacteria and germs are highly regulated to ensure a safe, high-quality water output that can be returned to nature.
Some metro area homes and businesses rely on septic systems in which wastewater is treated onsite. In these cases, water passes into a septic tank, where solid materials settle to the bottom and are broken down by bacteria. Liquids are passed onto a drainfield, where waste materials are broken down by bacteria in the soil. Homeowners should know that maintenance of the system is important for it to properly function. The solids in the septic tank must be pumped periodically—generally every five years is best.