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TYPICAL ROUTES OF GROUNDWATER CONTAMINATION
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Source: Adapted from Environmental Protection Agency, Office of
Water Supply and Solid Waste Management Programs, Waste Disposal Practices and Their Effects on Groundwater (Washington, D.C.: U.S. Government Printing Office,
1977).
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In 2000, some 9.94 million acre-feet -- nearly 63% of all water used in Texas -- came from under the ground *. Like surface water, groundwater is vulnerable to contamination from a variety of sources. In Texas, all nine
major aquifers and 20 minor aquifers have experienced some form of contamination. These contamination problems stem partly from land-based development and industry and partly
from overpumping, which causes infiltration of saline waters.
Despite these problems, state laws do not protect groundwater to the same extent as surface water. There are,
for example, no groundwater quality standards to parallel those for surface water. The state does have standards in place for groundwater utilized for drinking water. In addition, monitoring of groundwater is divided among a myriad of state and local agencies, although the amount of groundwater
monitoring has increased in recent years due mainly to increased efforts by the Texas Water Development Board *.
The legislature has also taken steps to protect groundwater. In 1989 the legislature created the Texas Groundwater
Protection Committee as an interagency committee to coordinate all state agency actions for the protection of
groundwater quality. In 1991 the state created an oil-field cleanup fund to plug abandoned oil wells and pits which has
helped prevent groundwater contamination. To protect endangered species and the sustainability of the Edwards
Aquifer in San Antonio, the legislature in 1993 created the Edwards Aquifer Authority, which in turn has enacted a
management plan and established a permit system for groundwater withdrawals to ensure adequate spring flows at
the Comal and San Marcos springs. The law gives the Edwards Aquifer Authority the power to set limits on pumping.
In 1997 the legislature passed SB 1, commonly referred to as the "Water Bill." While the intent behind the bill is to
ensure sufficient water quantity through a regional planning effort, drought management, conservation plans, and
emergency authorizations of water transfers during droughts, the legislation also deals with water quality. Groundwater
district management plans and regional water plans must address water quality. In addition, the bill authorizes the
TWDB to administer the Federal Safe Drinking Water Revolving Fund to provide low-interest loans to small communities for drinking water and wastewater treatment.* In 2001, under "Senate Bill 2," the Texas legislature clarified the
authority of groundwater districts to regulate water wells as well as additional types of wells, and gave them the power
to purchase groundwater rights for conservation, while also strengthening the enforcement powers of districts. These
measures -- among others -- could allow districts to better protect water quality.
Clean groundwater is needed for more than drinking purposes. Agriculture depends heavily on groundwater for
irrigation; in 2000, 80 percent of all groundwater pumped was used for crop irrigation .* Poor or contaminated
groundwater could jeopardize crops and threaten the health of livestock.Clean groundwater is also essential to clean
surface water. Groundwater is connected to surface water in the hydrological cycle, and some aquifers actually feed
area springs and rivers. For example, the Edwards Aquifer is the major source for Central Texas rivers through the
Comal and San Marcos springs. Poor quality water—or a lack of water—harms the springs.
Sometimes contamination occurs naturally. Saline water from deeper aquifers may reach aquifers that provide water
for humans. Some groundwater may have naturally high background levels of nitrates, metals, iron, sulfate, or chloride, all of which can give water an odd odor, color, or taste.
Groundwater contamination has become a major public policy concern in recent decades. Human activity on virtually
any piece of land in the state has the potential to affect groundwater quality, since 76 percent of the state's surface
area of 267,277 square miles lies above major and minor aquifers. A variety of potential threats to groundwater are the result of human activities.
Sources of Groundwater Pollution
It is difficult to ascertain how much groundwater contamination has resulted from human activities. Under a 1989 state
law, the legislature created the Texas Groundwater Protection Committee, which is currently composed of
representation from 10 state agencies. As part of its duties, the committee tracks instances of groundwater
contamination and the status of clean-up efforts through publication of an annual report. The committee, utilizing data
from all state agencies, reported that in 2002 there were still 7,069 groundwater contamination cases documented or
under enforcement, including 582 new cases of contamination. Some 739, however, were clean-up over the course of
the year, meaning that at the end of 2002, there will still 6,330 groundwater contamination cases needing further action. * These figures represent only the cases reported and confirmed. In addition to these instances of
groundwater contamination, action was completed on a total of 6,425 cases of groundwater contamination between 1989 and 2001.*
As the table makes clear, some of the leading sources of groundwater contamination in Texas include:
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ACTIVITY
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1989–2002 CASES WITH ONGOING CLEAN-UP
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TYPES OF CONTAMINANTS
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Underground and above-ground storage tanks
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5,185
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Gasoline, diesel, waste oil, kerosene, hydraulic fluid
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Industries
and land disposal facilities including hazardous waste facilities and unauthorized wastewater discharges
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538
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Trichloroethylene, arsenic, PCBs, VOCs, solvents, creosote, chromium, lead, heavy
metals, phenols, chlorides, pesticides, sulfates, cadmium
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Permitted and illegal municipal landfills
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19
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Total dissolved solids, chlorides, trichloroethylene, vinyl chloride
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Federal and state superfund hazardous waste sites
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78
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Arsenic, lead, chromium, benzene toluene, xylenes, PCBs, VOCs, pesticides,
trichloroethylene
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Brownfields, Voluntary clean-up abandoned hazardous waste sites
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916
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Arsenic, lead, chromium, benzene toluene, xylenes, PCBs, VOCs, pesticides,
trichloroethylene
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Septic tanks, CAFOs, Class V wells, sludge disposal, wastewater treatment facilities
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6
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Nitrates, chlorides, salt water, copper, selenium, iron, ammonia
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Public drinking water systems
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30
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Benzene, trichloroethylene, carbon tetrachloride, chromium
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Emergency spills and leaks
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2
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Benzene, toluene, xylenes, hydrocarbons, vinyl chloride
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Agricultural chemicals and pesticides
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42
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Arsenic, prometon, Atrazine, dicamba, metolachlor, propazine, bromacil, DDT
dieldrin, DDE, cyanize
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Oil and gas waste injection wells, underground and surface storage of oil and gas
and oil and gas waste
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217
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Sodium chloride, chlorides, refined oil, crude oil, hydrochloric acid, total
dissolved solids
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Reported by local groundwater districts
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6
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Lead, zinc, gasoline, diesel fuel, hydrocarbons, fecal coliform, sediment
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Source: Texas Groundwater Protection Committee, Joint Groundwater Monitoring and Contamination Report, 2002 (2003), Tables 1–3.
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