|
|
 |
|||||||||||||||||
|
||||||||||||||||||
Source Protection
Tacoma Water aggressively guards the sources of its water supply to provide safe and reliable drinking water for our customers. Protecting these water sources from potential contamination is the first step in ensuring that Tacoma Water is able to deliver safe drinking water that meets all state and federal standards. Preventing water quality problems and contamination from occurring at the source has proven to be the most cost-effective means of protecting public health and avoiding the expensive solutions that come with contamination. Protecting our sources of drinking water helps Tacoma Water maintain competitive rates. Tacoma Water's SourcesTacoma Water has long been known for its mountain supply of drinking water from the pristine Green River watershed.Did you know that Tacoma Water has two important sources of drinking water? The Green River Watershed and groundwater wells are both used to supply Tacoma's water.To view a map of Tacoma Water's service area click here. The Green River WatershedFor more than 80 years, Tacoma Water has managed the Green River watershed. This forested land serves as a collecting point for melting snow and seasonal rainfall. It covers 148,884 acres on the west flank of the Cascade Mountains between Chinook and Snoqualmie passes. Tacoma Water owns only 10 percent of the watershed but has agreements with other owners to limit activities to keep the Green River water supply pure and fresh. Currently the Green River can supply up to 72 million gallons of water each day. This water flows by gravity into Tacoma, which minimizes expensive pumping costs. Tacoma Water can supplement its Green River supply with water from seven wells located along the North Fork of the Green River. The North Fork well field normally can meet the same 72 million gallons per day production as the Green River in the winter and spring months. These wells are used only when the water in the river is too turbid (or cloudy), usually in the fall and winter when rain and snow melt washes soil sediment into the river. Tacoma Water is fortunate to have the very high quality Green River water, the North Fork wells, and an active watershed control program. Because of these, Tacoma Water is in a small group of water systems that is not required to filter the surface water. The Washington State Department of Health, Office of Drinking Water has determined that Tacoma Water does not need to build a water filtration plant as long as the requirements in Washington Administrative Code 246-290-690 are met. The requirements to remain unfiltered include watershed control, quality of the water at the source, redundant disinfection treatment components, and annual site inspections by the State Department of Health.Top of PageGroundwater Wells
The majority of the groundwater used by Tacoma Water comes from wells in the South Tacoma wellfield. The South Tacoma wells pump from very productive underground aquifers that stretch from the Nalley Valley all the way to Lakewood. Tacoma Water first began developing the wells in South Tacoma in the early 1930's and currently has 14 wells in this wellfield. Tacoma Water’s wells can pump about 60 million gallons per day. Not only have these wells been critical to the past and present of Tacoma Water, but they are critical to the future drinking water supply for our customers. During the summer months, Tacoma Water customers can use in excess of 100 million gallons of water per day. Because Tacoma Water can use only 72 million gallons per day from the Green River, the wells help meet peak summer water needs. The need for groundwater is expected to increase in the coming years as water demands continue to grow. These wells will be invaluable to help meet Tacoma Water’s future needs. Watershed Protection for the Green RiverThe watershed is surrounded by mountain ridges on three sides, and gates and guards strictly limit public access to minimize contamination that people and their activities can introduce. Every day, water from the river is sampled at the intake, which is where Tacoma Water diverts the water into the transmission pipelines that bring the water into the city. The watershed is also actively patrolled to inspect for the presence of unsanitary conditions and to enforce laws and regulations governing the protection of the water supply. In addition, weekly samples are taken throughout the watershed from tributary streams that feed the Green River. This helps Tacoma Water anticipate water quality problems before they have a chance to reach the intake. Groundwater Protection for Tacoma Water's WellsGroundwater supplies up to 40 percent of Tacoma's water in the summer and supplements the supply from the Green River at other times of the year. Tacoma Water samples its drinking water wells for bacteria and for traces of over 150 different metals and chemicals. Tacoma Water also samples several dedicated monitoring wells. Homes for approximately 30,000 people, as well as hundreds of businesses, are located above the underground aquifer that supplies the wells in the South Tacoma wellfield. A great many of these businesses use, handle and store chemicals that can contaminate groundwater. In addition, most homes have numerous household chemicals, pesticides, and fertilizers that can contaminate groundwater if they are disposed of or applied improperly. If a groundwater well is contaminated, Tacoma Water must either treat the water or replace the well so that enough water is available for customers. Both of these options are expensive. Preventing contamination is much less expensive and more effective than fixing a problem after it has occurred. Tacoma Water is working hard to educate both residents and businesses who are located in areas above our drinking water aquifers about ways to prevent contamination of our drinking water. For more information about what you can do to protect your drinking water, click here. Chemical Contamination in South TacomaIn the early 1980's Tacoma Water detected chemical contamination in some of the South Tacoma wells, which required some of the wells to be taken out of service. Investigation focused on several nearby areas in the Nalley Valley, where illegal disposal of chemicals are suspected to have occurred since around the time of World War II. The likely source of the chemicals found in the Tacoma Water wells was tracked down to an oil-handling facility operated by Time Oil. The investigation revealed reports and evidence of illegal disposal of chemicals onto the ground at the site. To make matters worse, a fire occurred at the site in March 1976, which likely resulted in additional chemicals being released onto the ground and washed into the aquifer. Following the investigation, the Time Oil site was designated as an Environmental Protection Agency Superfund site, and cleanup of the site is ongoing. Because of the chemical contamination, an expensive treatment system was installed on one of the contaminated wells. This treatment system, which uses air to strip the chemicals out of the water, continues to operate to the present day. By pumping and treating the water from this well, Tacoma Water not only removes the chemicals from the well, but keeps the contamination from spreading to other nearby wells. As a result of the drinking water contamination, the South Tacoma Groundwater Protection District, was formed in 1988. This district covers an area situated on environmentally sensitive land that lies over the South Tacoma aquifer. Commercial and industrial businesses in the area are subject to special regulations because the soil is highly permeable, increasing the risk of contaminating the water supply. The South Tacoma Groundwater Protection DistrictThe South Tacoma Groundwater Protection District was established in 1988 to help protect some of our most important wells. Businesses in the area are subject to special regulations because of the number of wells in the area and because the gravel and sand found just below the surface in much of South Tacoma allow water and hazardous chemicals, if present, to move quickly through the ground down to groundwater. The South Tacoma Groundwater Protection District ordinance is currently being revised to reflect the changes in hazardous waste practices, in federal, state and local regulations and the increased knowledge of the aquifer. For more information, or to comment on the South Tacoma Groundwater Protection District ordinance, call 502-8207 or 798-4783, or e-mail Waterquality. What You Can Do To help Protect Your Drinking WaterSuccessful protection of the groundwater depends on Tacoma Water, businesses and residents. It may seem like the actions of an individual won’t make a difference, but multiply that by the 30,000 residents living over the South Tacoma aquifer and you get an idea of how big a difference residents can make. You can help keep your drinking water safe by using fewer hazardous chemicals around your home. Hazardous chemicals, which can include motor oil, pesticides, fertilizers, and paints, used above ground have the potential to seep down into the groundwater that supplies the wells. You can adopt home, yard, and auto care practices that are safer for groundwater. Here are a few ways you can help keep your water safe:
To learn more, read these Tacoma Water publications: Or visit these Web sites: (Tacoma Water is not responsible for content of these Web sites and does not endorse products or services) Alternatives to hazardous household products Environmental Coalition of South Seattle WSU Extension’s Gardening in Western Washington WSU Extension’s Master Gardener Program WSU Extension’s Pesticide Education Program WSU Extension’s Integrated Pest Management Program You can also call Tacoma Water’s Water Quality division at 502-8702 or e-mail.
Updated: June 11, 2008
|
||||||||||||||||||
