When it rains, runoff picks up and carries a wide variety of pollutants into our storm water system. Pollutants such as bacteria, nutrients, metals, and chemicals are often found in contaminated storm water. This contaminated water then enters our municipal drainage system and ends up in our streams, rivers and lakes. Because most of the water in North Central Texas is contained in lakes, these pollutants affect the ability to safely swim and fish in these waters, as well as require expensive processes to remove contaminants and treat the water to drinking water quality.
Storm water pollution prevention is a city-wide activity, and the City of Irving has developed a storm water management plan. Nearly every department in the city has specific responsibilities under this plan. The Water Utilities Environmental Compliance Section is responsible for the following activities regarding storm water quality:
- Spill Response
- Sources of storm water pollution
Dry Weather Monitoring
Waterways in the City of Irving are monitored during periods when it has not rained. This provides staff with knowledge of the baseline water quality. Every year, a portion of the storm water outfalls are assessed to determine if any illicit discharge and improper disposal is occurring. In this manner, the complete storm drain system is completely screened for illegal discharges every five years.
In addition, streams in Irving are monitored on a monthly basis from a total of 30 different sites. Partnering with the Trinity River Authority, the city also participates in the Clean Rivers program. By combining sampling resources with other entities, more detailed information about the water quality in Irving and in North Central Texas is available.
Wet Weather Monitoring
The North Central Texas Council of Governments (NCTCOG), participating with the cities of Arlington, Garland, Irving, Mesquite and Plano, as well as the North Texas Tollway Authority and the Texas Department of Transportation, has developed and implemented a state-approved regional storm water monitoring program. Although not directly participating, the cities of Dallas and Fort Worth also commit resources to this program.
This monitoring program samples storm water runoff from in-stream sample sites and gathers data on the water quality during storm events on a watershed basis. Storm events also are monitored by Environmental Compliance staff. A minimum of eight storm events, from seven different watersheds, are sampled each year. This is accomplished using mobile, automated sampling equipment.
The Environmental Compliance Section enforces parts of the City of Irving Code of Civil and Criminal Ordinances Part II Chapter 41 Article X: Municipal Storm Water Drainage Regulations and Acts Adversely Affecting Water Quality Spill Response.
Hazardous Materials Spills
Working closely with the Irving Fire and Police departments as part of the City Hazardous Materials Response Plan, the Environmental Compliance section maintains an assortment of cleanup materials. In the case of small (less than 20 gallons) hazardous materials spills, Environmental Compliance personnel are capable of cleaning up many types of spills.
For larger spills or extremely dangerous materials, Environmental Compliance provides technical assistance, as needed, to the Fire Department. EC staff assumes command of the incident site once the cleanup phase of the operation is entered. Typically, an environmental contractor is employed to do the actual cleanup. Environmental Compliance personnel insure that, while the cleanup is taking place, the safety and health of Irving residents is not adversely affected and that the city's infrastructure is not impacted.
Storm Water Pollution Sources
- Human and pet waste; fertilizers; yard clippings such as leaves and grass
Human and pet waste contain disease-carrying bacteria. Raw sewage in our waterways makes water unusable for fishing, swimming and drinking. In addition, these substances all contain nutrients – another major pollution problem. The nutrients nitrogen and phosphorus not only cause grass to grow, but an excessive amount also causes algae to grow in our waterways. Algae blooms cause fish kills and block sunlight for the underwater vegetation needed by fish for food and other aquatic organisms.
- Sediment (soil, sand, silt, clay)
Sediment is easily transported by rain water and acts to clog fish gills, blocks sunlight for underwater vegetation, and destroys fish-spawning areas. It is the largest contributor of storm water pollution by volume.
- Automotive products such as motor oil, gasoline and antifreeze; hazardous waste such as cleaners and paints; and pesticides (herbicides, insecticides, fungicides, rodenticides)
These materials are toxic, so they are dangerous to humans and animals, as well as to the environment. Antifreeze, although improved, is still a particular hazard to pets and wildlife. Toxic substances in our waterways makes water unusable for fishing, swimming and drinking. One quart of used motor oil entering our waterways can contaminate an estimated 1 million gallons of drinking water.
- Solid waste and litter
These items decompose in water, removing oxygen needed for aquatic life. Solid waste also can clog the storm water system, contributing to street flooding and flooding of residences. Litter often ends up along the shores of our streams or floating in our lakes.