WHAT IS GROUND WATER?

Water that saturates underground earth material is called ground water. The earth acts as a "sponge" with ground water filling the spaces between soil and rocks. It moves slowly, typically in feet per year. An aquifer is a layer of sand, gravel or permeable rock with enough water to yield a useful amount.

WHERE DOES IT COME FROM?

Ground water is replenished, or recharged, by rain, snow melt, streams and other surface water seeping into the earth. Water recharges as it infiltrates down to where all the spaces between particles of soil and rock are filled with water, the saturated zone. The top of this zone is called the water table. The water table may be a few feet to hundreds of feet below the surface.

Ground water may seep out of the earth at springs, and sometimes flows into lakes and streams. Evaporation from soil and surface water and transpiration by plants complete the natural cycle of water movement, returning water to the air so that it can fall as precipitation once again.

WHY IS GROUND WATER A "TREASURE"?

About 90 percent of New Mexico’s 1.8 million people depend on ground water for drinking water, and it is the only source of potable water in many areas of the state. Therefore, protection of ground water is important for public health and welfare.

WHAT IS WATER QUALITY?

The quality of water is related to all substances contained within it, other than the water (H₂O) itself. A water contaminant is any substance that alters the physical, chemical, biological or radiological qualities of water. A contaminant becomes a pollutant when it exceeds an acceptable concentration or standard.

HOW PURE IS NEW MEXICO’S GROUND WATER?

The quality of ground water in New Mexico varies widely. It contains naturally occurring minerals that dissolve from the soil and rock that it has flowed through. Mountain aquifers, recharged by recent rain and snow melt, often yield high quality water. A tremendous amount of fresh water occurs in the Rio Grande valley fill aquifer, stretching from Colorado to Texas. Some ground water in the southern part of the state is too salty to be used for drinking. High levels of natural uranium occur in some ground waters in northern Santa Fe County, in the Grants-Gallup area, and in Quay County. Naturally high fluoride and arsenic also occur in various areas around the state.

The earth has natural cleansing processes that can filter out, dilute, transform or destroy both natural and human-made contaminants in the subsurface. Ground water becomes polluted when contaminants move through soil and aquifers faster than natural processes can reduce them to acceptable levels. Chemicals and micro-organisms can make ground water unpleasant to drink or pose health risks. Because all water eventually moves through the entire water cycle, pollutants in the air, on land, or in surface water can reach any other part of the cycle, including ground water. The shallow sand-and-gravel aquifers of the river valleys are most vulnerable to contamination.

IS GROUND WATER POLLUTED IN NEW MEXICO?

In some areas, yes. Populations in New Mexico have grown rapidly in the past few decades, and the number and variety of chemicals used at home and in industry has rapidly increased. Impurities traceable to human activities began appearing in New Mexico well water in the 1920s, and some people have become ill as a result of drinking polluted well water. Numerous public and private wells have become polluted and have had to be abandoned or equipped with purification units. Between the early 1920s and the end of 1999, over 1,400 instances of contamination had been identified by the New Mexico Environment Department (NMED).

WHERE DO GROUND-WATER POLLUTANTS COME FROM?

Sources of ground-water pollution in New Mexico include:

• an estimated 208,000 septic-tank systems and cesspools that discharge about 78 million gallons of wastewater per day to the subsurface, the single largest source of ground-water pollution in the state

• spills and leaks of gasoline, diesel, jet fuel, solvents and other hazardous materials from storage tanks, pipelines, and traffic accidents

• active or abandoned mines and mills, including waste-rock dumps, mill tailings, and pumping of water from mines (dewatering)

• pits, ponds, lagoons and other surface impoundments for liquid waste from city sewage treatment plants, factories, dairies, and oil and gas production sites

• solid waste disposal sites such as landfills, sludge beds, and illegal dumps

• improper disposal of industrial, military and laboratory waste

• dumping household hazardous waste into landfills, sewers or backyard pits

• improper storage of solid materials such as piles of road salt, composting manure, and mined ore

• improperly constructed waste-injection wells

• over-application of fertilizers and pesticides

• evapotranspiration of irrigation water

• deliberate, knowing, and criminally illegal dumping by businesses and persons who fail to obtain or comply with discharge permits (eg. clandestine drug labs)

WHAT POLLUTANTS HAVE BEEN DETECTED IN GROUND WATER?

The pollution sources listed above have released a wide variety of chemical and biological substances into ground water. Chemical contaminants include inorganic, radioactive and organic substances. Commonly detected inorganic contaminants include, nitrate, sulfate, chloride, iron, and manganese, which often occur naturally at some background level. Excess concentrations originate from many sources, especially household and city sewage systems, mines/mills, landfills, and a variety of industries. Cyanide and the metals arsenic, cadmium, chromium, copper, molybdenum, nickel, selenium, vanadium and zinc have been detected in contamination plumes from mines/mills and metal plating industries.

Most ground water in the state contains low levels of one or more naturally occurring radioactive elements like uranium, radium or radon. Excess concentrations are found at uranium mines/mills. Human-made radionuclides, like tritium and plutonium, also have been detected in ground water.

Organic contaminants of concern include a complex variety of chemicals. Petroleum hydrocarbons, like benzene, are most commonly detected due to the large number of spills of gasoline, diesel, etc. Chlorinated solvents, such as trichloroethylene, are used by industry, and are common contaminants. Other organic solvents, pesticides, and high explosives also have been detected in New Mexico ground water.

Here are some examples of the molecular structures of organic contaminants.

Ground water contains naturally occurring bacteria, most of which, when ingested in drinking water, do not make humans sick. Ground water contaminated by human and animal waste, however, may contain disease-causing organisms (pathogens). The presence of fecal coliform bacteria (like E. coli) in ground water is a serious health hazard.

WHAT ARE THE HEALTH HAZARDS OF GROUND-WATER POLLUTANTS?

For free chemical toxicology databases, go to:

• http://www.atsdr.cdc.gov/toxfaq.html

• http://ehis.niehs.nih.gov/ntp/docs/chem_hs.html

WHAT ARE THE ACCEPTABLE LIMITS FOR CONTAMINANTS IN GROUND WATER?

For lists of state and federal ground-water and drinking-water standards, go to:

• Federal and State Groundwater Standards

• http://www.epa.gov/waterscience/drinking/

ARE THERE LAWS TO PROTECT GROUND-WATER QUALITY?

Yes. The New Mexico Water Quality Act, passed into law in 1967, specifically included ground water within its scope, unlike the federal law at that time. The Act created the New Mexico Water Quality Control Commission and authorized it to adopt ground-water quality regulations and standards. The Commission has set numerous standards for contaminants in ground water, and has adopted regulations requiring permits for the discharge of water contaminants onto or below the surface of the earth. Regulations requiring notification and clean up of spills, and abatement of ground-water pollution, also have been adopted. New Mexico’s water quality regulations aim to protect all ground water of potentially usable quality from pollution. New Mexico’s experience has shown that conscientiously enforced, sound regulations for preventing ground water pollution can be extremely effective. The New Mexico Water Quality Act also provides civil and criminal penalties for violation of the regulations and standards.

Other New Mexico laws that protect ground water include the Solid Waste Act, the Hazardous Waste Act, the Environmental Improvement Act, the Oil and Gas Act, the Ground Water Protection Act, and the Voluntary Remediation Act. Each of these laws authorized the adoption of regulations to protect ground water from various sources of pollution. There are also federal laws that regulate ground-water quality.

CAN GROUND-WATER POLLUTION BE CLEANED UP?

Not always. Once contaminated, ground water is difficult, or, in some cases, impossible to return to its original quality. Common methods of cleanup include:

• removal and recycling of oil floating on top of the water table (free-product recovery);

• pumping contaminated ground water out and treating it (pump-and-treat);

• blowing air into the aquifer and vacuuming contaminant vapors out from the soil (sparge-and-vent);

• stimulating native ground-water bacteria with oxygen, food and/or nutrients to enable them to more rapidly biodegrade pollutants into harmless byproducts (enhanced bioremediation); and

• if there are no imminent risks to public health and welfare, monitoring natural abatement processes as they reduce contaminant concentrations to within standards (monitored natural attenuation).

Restoration of ground-water quality often takes decades to accomplish, and can be very expensive.

IS IT MORE ECONOMICAL TO PREVENT OR CLEAN UP GROUND-WATER POLLUTION?

Prevention is always more economical than cleanup. Employing a NMED scientist to review ground-water discharge permits for new activities, and to conduct site inspections to ensure that facilities comply with permit conditions, may cost the state $50,000 per year. But a single aquifer investigation and cleanup can cost industry or government anywhere from $50,000 to $25 million. Some contamination can never be removed.

The owner of a gas station installing a new underground storage tank that meets regulatory requirements aimed at preventing leaks may spend $35,000, but cleanup of ground-water pollution from one leaking tank typically costs $50,000 to $300,000 or more.

The costs are similar for other potential sources of pollution. Short-term business gains may result in long-term economic drains on both business and government.

WHAT CAN I DO TO PROTECT GROUND WATER AND MY FAMILY’S HEALTH?

• Learn about your water supply. If all or part of it is from ground water, find out where it comes from, where the areas of recharge are, and the direction of ground-water flow.Recycle your used motor oil. Some service stations, auto parts stores, and auto dealers accept it for recycling especially if you do business with them.

• Find out what activities are going on in areas of recharge and "uphill" from your well. Find out how and where local industry disposes of its waste.

• Develop a Wellhead Protection Plan in your community to identify and monitor actual and potential sources of contamination.

• If you are served by a public water utility, obtain a copy of the annual drinking-water quality report from your city or water company.

• If you have a private domestic well, get your water tested for free by NMED during the next "Water Fair" in your community. You can also send samples to a commercial laboratory.

• Measure the distance between your private well and the closest septic system leach field. If it is less than the legal minimum of 100 feet (200 feet for public wells), have your water tested for nitrate and bacterial contamination and plan to relocate your well or septic system if there is a problem.

• Drill your new private well at least 100 feet (200 feet for public wells) from the nearest septic system leachfield or other potential source of pollution and design it so that the shallowest water

• Recycle your used motor oil.  Some service stations, auto parts stores, and auto dealers accept it for recycling especially if you do business with them.

•        Patronize businesses that practice pollution prevention.  Look for the “Green Zia” symbol on display, and tell the proprietor that this is a GREEN ZIA    factor in why you are doing business there.

• Identify toxic chemicals that you use in your home, both indoors and in the lawn or garden. Read labels on containers and use proper handling and disposal procedures. For a free database on chemical hazards, go to:

http://www.cdc.gov/niosh/ipcsneng/neng0000.html#X

• Purchase or mix only the amount of chemicals you need right now. Do not over-apply fertilizers and pesticides. Do not dispose of unused chemicals by dumping them down the drain, toilet, or into a backyard pit. They can upset your city wastewater system or your septic system and may contaminate water supplies and harm aquatic life.

• Tell your legislators and local officials that you support ground-water protection.

• Support strong state and local health and environmental laws, regulations and ordinances, subdivision codes, and ground-water management programs.

• Promptly report any suspected ground-water contamination or illegal dumping to NMED. Call toll-free 1-800-879-3421.

WHERE CAN I GET MORE INFORMATION AND TECHNICAL ASSISTANCE?

NMED has many staff experts, and offices throughout the state to assist citizens with pollution-prevention, waste-disposal, water-well and ground-water protection issues. NMED’s toll-free phone number is 1-800-879-3421.

http://www.nmenv.state.nm.us/

has links to all program web sites, laws, and regulations, and to many staff and other sources of information.

NMED’s central office is in Santa Fe. To find the district or field office nearest to your community, look in the government pages of your telephone directory or go to:

http://www.nmenv.state.nm.us/field_op.html

NMED also conducts periodic "Water Fairs" around the state during which residents can get their well water tested for free. To find out more about Water Fairs, Contact the NMED Drinking Water Bureau toll-free at 1-877-654-8720.

For a children’s water web site, go to:

http://www.epa.gov/kids/water.htm

DISCLAIMER

This is a non-regulatory document, prepared and distributed for the purposes of public outreach and education. Any questions of a regulatory nature should be directed to the appropriate NMED program.

ACKNOWLEDGEMENTS

This publication was prepared by the NMED Ground Water Quality Bureau funded, in part, by a grant from the U.S. Environmental Protection Agency, pursuant to Section 106 of the Clean Water Act. Dennis McQuillan, Anna Richards, and Jennifer Parker, of NMED, are the authors of this document. 

Cover figure is Avanyu, the Native American plumed-serpent deity, guardian of springs and watercourses.