Stormwater / Drainage System Information : Stormwater

What is Stormwater Management?

Managing the quantity and quality of stormwater to control flooding and erosion, preventing contaminants from polluting surface or groundwater resources. This management is done by directing water runoff into a maze of pipes that make up the stormwater system, allowing water to travel to either a detention pond or retention pond.

The District operates a municipal separate storm sewer system (MS4) that is regulated by the Texas Commission on Environmental Quality (TCEQ) under its Texas Pollutant Discharge Elimination System (TPDES) general permit number TXR040000. Under this program, the District developed a Storm Water Management Program (SWMP) that outlines actions that the District will take to ensure compliance with the Clean Water Act and the Texas Water Code. The plan is organized around seven control measures:
        1. Public Education and Outreach 
        2. Public Involvement/Participation 
        3. Illicit Discharge Detection and Elimination  
        4. Construction Site Runoff Control 
        5. Post-Construction Site Runoff Control 
        6. Good Housekeeping/Pollution Prevention
        7. Authorization for Municipal Construction Activities

A link to the District's Stormwater Management Program is below.

What is storm water runoff and where does it go?

Storm water runoff is water that flows after a rainfall. During rainstorms, water drains off driveways, parking lots, rooftops and streets picking up pollutants while flowing to the storm sewer system. Once storm water enters the storm sewer system of inlets, pipes or channels, it flows downstream to the nearest detention or retention pond, creek, lake or river. Rainfall and urban runoff are two types of stormwater runoffs which, if left unmanaged, can create major issues related to flooding and/or potential contamination of nearby streams or other bodies of water. Urban runoff is water from irrigation, overwatering, car washing and other similar sources that flow into the street picking up pollutants and then entering the stormwater system. Both types of runoffs can pick up and carry pollutants into the stormwater system. These pollutants need to be reduced or removed before entering and contaminating local ponds and waterways. 

What is a Detention / Retention Pond? 

Detention ponds are normally dry, they temporarily store excess stormwater and urban runoff. The water runoff flows into the dry pond which helps reduce flooding. The water will slowly drain back onto adjacent land features while allowing some trash, pollutants and sediments to settle to the bottom of the dry basin. These ponds are not meant to store runoff for long periods of time.

Retention ponds, although like a dry pond, they are meant to store a specific volume of stormwater for a long period of time. Usually larger than dry ponds the retention pond is designed to maintain a permanent water level. Retention or "wet" ponds look like small ponds or wetlands and may have a landscaped look around the edges. Much of the vegetation found in wet ponds is planted to specificalley treat the water.

The District has 13 dry ponds and 11 wet ponds. All are inspected at various times throughout the month. District staff will remove trash, place mosquito dunks in standing water and check the piping used to discharge runoff into the receiving pond for any type of blockage. The District also contracts with an outside vendor for regular maintenance on all the wet ponds. This contractor will also remove trash, but their focus is keeping the vegetation in the pond under control. Proper vegetation will remove a significant amount of pollutants found in the water. This vegetation grows quickly, and the contractor will use environmentally safe herbicides to kill the excess plants which are ultimately cut out and disposed of.    

What is the difference between the storm sewer system and sanitary sewer system? 

The water that goes down the sanitary sewer system (from sinks or toilets) flows to a wastewater treatment plant where it is treated and filtered prior to entering any water bodies.

The storm water and urban runoff water that flows down driveways and streets and into the storm sewer system flows directly to our ponds, creeks, lakes and rivers. Anything that enters a storm sewer system is discharged untreated into the water bodies we use for swimming, fishing, and providing drinking water. 

The effects of pollution

Polluted storm water runoff can have many adverse effects on plants, fish, animals and people.

  • Sediment can cloud the water and make it difficult or impossible for aquatic plants to grow.
  • Sediment also can destroy aquatic habitat.
  • Bacteria and other pathogens can wash into swimming areas and create health hazards.
  • Excess nutrients can cause algae blooms. When algae die, they sink to the bottom and decompose in a process that removes oxygen from the water. Fish and other aquatic organisms can’t exist in water with low dissolved oxygen levels.
  • Household hazardous wastes like insecticides, pesticides, paint, solvents, grease, used motor oil and other auto fluids can poison aquatic life. Land animals and people can become sick or die from eating diseased fish or ingesting polluted water.
  • Debris—plastic bags, six-pack rings, bottles and cigarette butts—washed into creeks and water bodies can choke, suffocate, or disable aquatic life like ducks, fish, turtles and birds.

Polluted storm water often affects drinking water sources. This, in turn, can affect human health and increase drinking water treatment costs.

What can you do to help?

For more information or to inquire about volunteer opportunities call (512) 255-7871 x408 or e-mail To report illegal dumping into our storm drains or waterways, contact the District at (512) 255-7871 x410. The largest source of storm water pollution are pollutants such as litter, pet waste, pesticides, fertilizers, leaves and yard clippings and automotive leaks and spills. These materials are swept away with the storm water and produce what is referred to as non-point source pollution. Harmful bacteria, chemicals, sediment and litter enters or blocks the storm drain and leads to flooding, impaired water quality and endangers the health and habitat of local wildlife.