Wellhead Management Background

About 95 percent of this country’s rural resi-dents use ground water to supply their drink-ing water and homestead needs. Wells shouldbe designed to provide clean, safe water. Ifimproperly constructed or maintained, howev-er, wells can allow bacteria, pesticides, fertiliz-er or oil products to contaminate ground water.These contaminants can put family and animalhealth at risk.

The condition of your well and its proximityto contamination sources determine the risk itposes to your ground water. For example, acracked well casing may allow fertilizer,nitrates, oil or pesticides to enter the well ifthese materials are spilled near the well.Feedlots, animal yards, septic systems andwaste storage areas also can release largeamounts of bacteria, nitrates and other contam-inants that could pollute well water.

The Texas Water Well Drillers Act (1985), theWater Well Pump Installer Act (1991) and vari-ous other legislative actions have guided devel-opment of regulations, primarily contained inChapter 287 of the Texas Administrative Code,to provide for licensing of well drillers andpump installers and establish standards fordrilling, capping and plugging water wells. Forwells drilled before the effective date of cur-rent regulations (1983), well owners are respon-sible for ensuring that their wells do not conta-minate ground water. Contact a licensed welldriller or the Texas Natural Resource Conser-vation Commission for additional information.

Preventing ground water contamination isvery important. Once ground water is contami-nated, it is very difficult to restore it to its orig-inal condition. Most options are costly, andcould involve treating the water, drilling a newwell or obtaining water from another source. Acontaminated well also can affect neighboringwells, posing a serious health threat to others.

A glossary at the end of this bulletin willclarify the terms used. This guide will coverthe following areas of wellhead management:

1) Well location2) Well construction3) Well age and type4) Well depth5) Maintaining existing wells

6) Water testing7) New wells8) Unused and abandoned wells

Well Location

Whether a well taps water just below theground or hundreds of feet deep, its surfacelocation is a crucial safety factor. Locating awell in a safe place takes careful planning.Such factors as where the well is in relation tosurface drainage, how the land is used, wherechemical mixing and storage areas are located,and the direction of ground water flow must beconsidered. A well downhill from a livestockfeeding facility, a leaking tank or a septic sys-tem has a greater risk of contamination than awell on the uphill side of these potential pollu-tion sources.

Surface slope does not always indicate thedirection a pollutant might flow once it getsinto the ground. In shallow aquifers, groundwater flow is often in the same direction assurface water flow. If the aquifer supplyingwater to your well is deep below the surface,though, its slope may be different than that ofthe land surface. Finding out about groundwater movement on your property may requirethe use of special monitoring equipmentinstalled and operated by trained personnel(see Contacts and References).

States encourage proper well location byrequiring minimum separation distances fromsources of potential pollution, thus using thenatural protection provided by soil. Texas regu-lations for private water well drilling and con-struction (Texas Administrative Code NR 31,Chapter 287) provide guidelines for pesticidemixing, pesticide and fertilizer storage, vehiclemaintenance, animal waste disposal, and otherimportant activities. When no distances arespecified, provide as much separation as possi-ble between a well and any potential contami-nation source. This is especially necessary ifyour property is on highly permeable soils orthin soil overlying limestone bedrock, or if thecontamination source or activity presents ahigh risk of contamination.

Minimum separation distances apply to newwell installation in Texas (Fig. 1). Existing wellsare required by law only to meet separationrequirements in effect at the time the well wasconstructed. However, it is to your family’s

benefit that you make every effort to exceedold requirements and meet current regulationswhenever possible. Differences in soil andslope can make well siting an inexact science.Keep in mind that separation distancesrequired by the State of Texas and some groundwater districts are minimums. You may want to

choose greater separation distances in somecases, depending on conditions at a particularsite. For more information on the soil charac-teristics and geologic material of your well site,refer to those tables in B-6023, TEX*A*SYSTIntroduction.

50 feet

100 feet

150 feet

150 feet

250 feet

WELL

Figure 1. Minimum separation distances between well and potential farmstead sources of contamination for new well installation.

★ pesticide or fertilizer storage tank (less than 1500 gallons; non-potable wells only)

★ cistern★ nonpotable well

★ septic tank★ sewage holding tank★ liquid waste collection facility

★ animal shelter or yard★ feed storage facility, glass-lined★ manure hopper or reception tank, liquid-tight★ filter strip★ silo without pit, but with concrete floor and drain★ soil absorption unit (less than 8000 gallons/day)

★ gasoline and other liquid petroleum products★ underground★ surface (more than 1500 gallons)

★ fuel oil tanks★ underground★ surface (more than 1500 gallons)

★ manure storage structure, fabricated, liquid-tight★ pesticide or fertilizer storage tank (more than 1500 gallons)

★ liquid waste disposal system★ manure stack★ manure storage structure, earthen or excavated

For sources not addressed: Provide as much separation as possible from well.

These are suggested distances for well separation. Local waste storage ordinancesmay require different separation distances.

Changing the location of a well in relation tocontamination sources may protect your watersupply, but not the ground water itself. Anycondition likely to cause ground water contami-nation should be prevented, even if a well isfar away from the potential source. Whether ornot drinking water is affected, ground watercontamination is a violation of Texas law (TexasWater Code Chapter 26). This law states thatthere shall be no lessening of ground waterquality below the present quality.

Simply separating a well from a contamina-tion source may reduce the chance of pollu-tion, but it does not guarantee that the wellwill be safe. Wells located in the path of pollut-ed water have a high risk of contaminationfrom overland flow washing into an improperlysealed well.

Well Construction

Poor well design can cause ground watercontamination by allowing precipitation andstorm runoff to reach the water table withoutfiltering through soil. Wells located in pits andwells without grout or caps can allow surfacewater to carry bacteria, pesticides, fertilizer oroil products into your drinking water supply.Proper well design and construction reducesthe risk of pollution by sealing the well fromanything that might enter from the surface.

Well characteristics important to proper wellconstruction are described in the following sec-tions. Information about the construction ofexisting wells may be available from the personwho drilled the well, the previous owner or thewell driller’s report. The Texas NaturalResource Conservation Commission canattempt to locate the driller’s report for you fora small fee.

Well Casing Slab and Cap

During construction the well driller installs asteel or plastic pipe called a casing to preventcollapse of the borehole. The space betweenthe casing and the sides of the hole provides adirect channel for surface water (and pollu-tants) or ground water from undesirableaquifers to reach your drinking water. To sealthat channel, the driller fills the space withgrout (cement or concrete). Together, the groutand the casing prevent pollutants from seepinginto the well (Fig. 2).

You can inspect the condition of a well cas-ing at the surface by searching for holes orcracks. Use a light to check down the inside ofthe casing. If you can move the casing aroundby pushing against it, the casing probably failsto keep out contaminants. Also check the con-dition of the well casing by listening for waterrunning down into the well when the pump isnot running. If you do hear water, there couldbe a crack or hole in the casing, or the casingmight not extend down to the water level inthe well. Either situation may be risky.

A slab must be constructed around the cas-ing at the ground surface. The slab mustextend at least 2 feet from the well in all direc-tions, be at least 4 inches thick, and slope awayfrom the casing to drain water away from thewell. In areas with high shrink-swell clays, theslab should be separated from the well casingby a plastic or mastic coating or sleeve to pre-vent bonding. The casing must extend at least1 foot above the slab for most wells. If unde-sirable water is encountered in the drillingprocess, it must be sealed off to prevent conta-mination of other water.

To prevent contaminants from flowing downinside the well casing, the driller installs a tightfitting well cap that can’t be easily removed bychildren. The well cap should keep out insects,animals and surface water, but have a screenedvent so that air can enter the well. Check thewell cap to see that it is in place and tightlysecured. Wiring should be in a conduit. If yourwell has a vent, be sure it faces the ground, istightly connected to the well cap or seal, and isproperly screened to keep out insects and ani-mals.

Casing Depth and Height

The depth of casing required by the stateprivate well code for any particular welldepends on the nature of the subsurface geo-logic materials. Minimum requirements forunconsolidated formation wells (sand and grav-el) are that casing should extend to a depth of25 feet or 10 feet below the static water (waterlevel in the well), whichever is deeper. Casingshould extend to at least 30 feet for sandstonewells, and at least 40 feet for all other bedrock-type wells.

A well cased below the water level in thewell provides greater protection from contami-nation because surface water is filtered through

soil and geologic materials before entering thewell. Typically, the casing extends 1 to 2 feetabove surrounding land, preventing surfacewater from running down the casing or on topof the cap and into the well. The Texas WaterCode requires that at least 12 inches of casingpipe extend above the top of the slab. The codealso requires that the casing extend at least 2feet above flood level.

Well Age and Type

Well age is an important factor in predictingthe likelihood of contamination. A well con-structed more than 50 years ago is likely to benear the center of the property; generally it is arelatively shallow well and is probably sur-rounded by many potential contaminationsources. Older well pumps are more likely toleak lubricating oils, which can get into thewell. Older wells also are more likely to havethinner casing that may be corroded through.Even modern casing in wells 30 to 40 years old

is subject to corrosion and perforation. If youhave an older well, you may want to have itinspected by a qualified well driller.

Dug wells pose the highest risk of drinkingwater contamination because they are shallowand often poorly protected from surface water.A dug well is a large-diameter hole, usuallymore than 2 feet wide, which is often con-structed by hand.

Driven-point or sand point wells, which posea moderate to high risk for contamination, areconstructed by driving assembled lengths ofpipe into the ground. These wells are normallysmaller in diameter (2 inches or less) and lessthan 50 feet deep. This type of well can beinstalled only in areas of relatively loose soils,such as sand.

All other types of wells, including those con-structed by a combination of jetting and dri-ving, are drilled wells. Drilled wells for farmand homestead use are commonly 4 to 8 inchesin diameter.

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Source: Adapted from University of Wisconsin Farm•A•Syst - Fact Sheet WL August 1991

Typical Domestic Well Installation

Sampling Faucet

Pressure Switch

Discharge Pipe

Concrete �Slab

Electrical Control Line

Electrical Control box

Fine Textured Soil

Cement slurry extending 10' below ground surface

Sand Lenses

Fine Sand

Sand and Gravel

Pump

Drop Pipe

Well Casing

Plastic coating to prevent seal

Pressure Tank

Screen

1' 2'4"

Figure 2. Typical domestic well installation with discharge pipe extending into the home.

Well Depth

Shallow wells draw from the ground waternearest the land surface, which may be pollut-ed by surrounding activities. Depending onhow deeply the well casing extends below thesurface, rain and surface water soaking into thesoil may carry pollutants into the well bore.

Local geologic conditions determine howlong it takes for this to happen. In some places,such as in karst terrain, this process happensquickly, in weeks, days or even hours. Areaswith thin soil over fractured bedrock or sandand gravel aquifers are particularly vulnerable.Even sites with thick sands over bedrock arevulnerable to contamination. On the otherhand, thick clay soils can slow the movementof contaminants to the water table.

Wells deeper than 100 feet are safer thanshallow wells because the ground water sup-plying deep wells may have traveled a consid-erable distance underground over a long time,which filters contaminants.

Existing wells were most likely locatedaccording to traditional practices or regulationsin place at the time of construction. Whilethese wells are still legal, you may want to con-sider how the well conforms to current stan-dards, which incorporate new knowledge aboutprotecting ground water. These standards canbe found in the Texas Administrative Code,Chapter 287.

Maintaining Existing Wells

Good maintenance means testing the waterevery year, keeping the well area clean andaccessible, keeping pollutants as far away aspossible and periodically (every few years) hav-ing a qualified well driller or pump installercheck the well mechanics.

Older wells without proper casing, sealingand protective slabs, or with other problems,should be brought up to current standards foryour own protection. Upgrade wells by gettingrid of well pits, installing caps, extending cas-ings, and moving such activities as pesticidemixing, tank rinsing or gasoline storage fartherfrom your well. Almost all Texas propertytransfer forms include clauses about under-ground petroleum storage tanks and well watersafety. If your well is in a storage shed or wellhouse, do not store contaminants such as fuelsor pesticides next to it. Do not winterize the

well by wrapping pipes and pressure tankswith empty fertilizer or pesticide bags or othermaterials containing potential contaminants.

Pollution Source Management

It is expensive to change the location ofsome facilities such as livestock feeding areasor silos. Until you can meet minimum separa-tion distance requirements, change the wayyou manage such structures to control contami-nants.

If your silo is too close to your well, forexample, you could install a system for collect-ing rainfall runoff draining from freshly ensiledforage. Likewise, you could install concretecurbs to direct livestock yard runoff away fromthe well.

Short-term stacks of wet manure can conta-minate a well with bacteria and nitrates. Locatethem 250 feet away from wells to reduce thechance of polluting your drinking water.Protect the stacks from rain to prevent leachatefrom entering the soil.

Other management changes you may wantto consider include moving traffic areas andchemical or gasoline storage areas away fromthe well, and upgrading or managing the septicsystem.

Backflow Prevention

Backflow or back-siphoning from pesticidemixing tanks allows chemicals to flow backinto the well through the hose. Use an anti-backflow device when filling pesticide sprayertanks to prevent the chemical mixture fromflowing back into the well and contaminatingground water. Inexpensive anti-backflowdevices for hoses used to fill sprayers are avail-able from irrigation and spray equipment sup-pliers and hardware stores. If you do not havesuch a device, keep the hose above the level ofthe liquid in the tank when filling the pesticidesprayer.

Consider purchasing an inexpensive plasticnurse tank. A nurse tank is filled with water atthe well and then used to fill the sprayer awayfrom the well. For more information aboutpreventing well contamination from pesticidemixing and loading practices, see theTex*A*Syst publication, B-6025 Reducing theRisk of Ground Water Contamination byImproving Pesticide Storage and Handling.

Water Testing

Keep an eye on water quality in existingwells by testing annually. Although you cannothave water tested for every possible pollutant,some basic tests can indicate whether or not aproblem exists.

At a minimum, test water annually for bacte-ria and nitrates. Where the well draws fromsandy materials or bedrock, testing at leastonce for corrosivity is also important. A goodinitial set of tests for a private well includeshardness, alkalinity, pH, conductivity and chlo-ride. A visual interpretation of the water sam-ples, as well as taste and odor tests, can pro-vide valuable clues about possible contamina-tion.

Test for contaminants that are most likely onyour property. Test for lead if you have leadpipes or soldered copper joints, or are con-cerned about lead in the brass associated witha submersible pump (see Extension publicationL-5096, Lead Contamination in Water Wells).Test for volatile organic compounds (VOCs) ifthere has been a nearby use, spill or produc-tion of oil, petroleum or solvent. While testingfor pesticides can be very expensive (often $80to $100 per compound analyzed), the expensemay be justified if:

★ a well has nitrate levels greater than 10mg/l (reported as nitrate-nitrogen, NO3-N)or 45 mg/l (reported as nitrate, NO3);

★ a pesticide spill has occurred near the wellor back-siphonage has occurred;

★ a well is shallow, with less than 15 feet ofcasing below the water table; or

★ a well is located in sandy soil and down-slope from irrigated croplands where pes-ticides are used.

For more information on appropriate tests torun, contact your county Extension office,health department, ground water conservationdistrict, or the Texas Natural ResourceConservation Commission.

Test well water if any of the following occur:

★ a notable change in water taste, odor,color or clarity;

★ an unexplained illness in the family;

★ a pregnancy in the family;

★ any noticeable changes in livestock orpoultry performance;

★ neighbors find a particular contaminant intheir water;

★ a spill or backsiphonage of chemicals orpetroleum products near a well or nearyour home;

★ chemical or manure application to fieldswithin 100 feet of a well;

★ livestock operation inspectors require it;

★ landfills or changes in land use nearby; or

★ a new well is drilled.

You can have water tested by both publicand private laboratories. A list of certified labsis available from the Texas Natural ResourceConservation Commission and the TexasAgricultural Extension Service Soil and WaterLaboratory.

Follow the lab’s instructions for water sam-pling to ensure accuracy of results. Use onlythe container provided and return samplespromptly. Bacteria sample bottles are sterileand must be returned within specified timelimits.

It is also important to record test results andto note changes in water quality over time. Inaddition to water analysis test results, youshould keep records on well constructiondetails, water levels and dates, and mainte-nance intervals for the well and pump.

New Wells

New wells are expensive, but they are agood investment for the future. Getting themost from such an investment means locatingthe well away from contamination sources andworking to maintain the quality of the well.Here are some simple principles to follow:

★ Follow the state recommended minimumseparation distances. Texas law statesthese separation distances and otherrequirements for drinking water wells. Afull listing is also available from yourcounty Extension office, the Texas NaturalResource Conservation Commission, or awell driller.

★ Locate your well on ground higher thansurrounding pollution sources such as fuel

tanks, livestock yards, septic systems orpesticide mixing areas.

★ Construct a concrete pad around the wellso that all surface water drains away fromit, as required by law.

★ Avoid areas that are prone to flooding.

★ Locate the well so that pollution sourcesare downslope from the well. Groundwater generally flows from upland areasand discharges into a surface water body.

★ Make the well accessible for pump repair,cleaning, testing and inspection.

★ Hire a competent, licensed well driller andpump installer. Make sure the driller dis-infects the well with chlorine after con-struction, tests the water for bacteria afterdrilling, and provides you with detailedinformation about the well’s depth andconstruction.

Unused and Abandoned Wells

Many farms and ranches have unused wells.Wells at old home sites or old windmills arecommon. No one knows how many of thesewells there are in Texas, although estimatesrange into the tens of thousands. Sources ofinformation on well locations include the TexasWater Development Board, the Texas NaturalResource Conservation Commission, under-ground water conservation districts, andlicensed water well drillers.

If not properly plugged, these abandoned orunused wells can provide a direct conduit forsurface water carrying pollutants to groundwater, or these abandoned wells can allow con-taminants to move from one aquifer to another.One improperly sealed well in Texas wasburied with only a stone covering the top ofthe casing. This well caused severely contami-nated drinking water to be pumped fromanother well on the same property. The unusedwell was near a livestock corral and a septictank. It allowed animal waste to directly enterthe ground water. Just as unused wells pose athreat to ground water, large open wells posesafety hazards for small children and animals.

Everyone remembers the baby Jessica inci-dent in which a young girl playing in her back-yard fell into an abandoned well. Hire a licens-

ed, registered well driller or pump installer toclose old wells, since effective well pluggingcalls for experience with well constructionmaterials and methods, as well as a workingknowledge of the geology of the well site. Youmay, however, do your own well abandonmentwork. A license is not required, but you mustmeet the minimum well code requirementswhen you abandon and fill a well.

Regulations in Texas Water Codes provideguidelines for properly plugging abandonedwells. Special equipment is often required toremove old pumps and piping and to properlyinstall sealing material inside the well. Use ofinappropriate materials and methods can leadto well settling, collapse and potential groundwater contamination. If plugging materials areimproperly installed in a well, patching updefective work is nearly impossible.

Pipes sticking out of the ground or under anold windmill are the most obvious ways tolocate unused wells. You may not know thehistory of your property, and unused well loca-tions may not be obvious. A depression in theground may indicate an old well. Also, wellswere often drilled in basements of houses,under front steps, and near old cisterns.

State regulations require that plugged wellsbe reported, and that the following be done:

★ Remove the pump, piping, and any otherobstructions from the well.

★ Chlorinate the well before it is sealed. Theentire length of the well should then besealed with slurries of cement or clay toprevent surface water from entering theground water and to prevent contaminantmovement from one aquifer to another.

★ Restore as closely as possible the geologicconditions that existed before the well wasconstructed. For specific requirements,consult the Texas Natural ResourceConservation Commission well abandon-ment brochure (see Contacts andReferences) or the well code.

Proper well closing takes time and money.Costs will vary with the well depth, diameterand the geology of the area. Spending a fewhundred dollars plugging an unused well nearyour home may prevent contamination of yourdrinking water.

Evaluation Table

The following table can be used to help agri-cultural producers and rural homeownersdetermine the risk that drinking water on agiven property will be contaminated by themanagement practices being used. For eachcategory on the left, read across to the right

and circle the statement that best describesconditions on your land. Allow 15 to 30 min-utes to complete the worksheet, and skip anycategories that do not apply. Note any high riskratings and take appropriate actions to remedythem. Strive for all low or low to moderate riskratings.

*See Glossary.

Drinking Water Well Condition: Assessing Drinking Water Contamination Risk

Low Risk Low-Moderate Risk Moderate-High Risk High Risk

Position of Upslope from all Upslope from or at Downslope from most Settling or depres-drinking water well pollution sources. grade with pollution pollution sources. sion near casing.in relation to No surface water sources. No surface Some surface water Surface water run-pollution sources runoff reaches well. water runoff reaches runoff may reach well. off from livestock

Surface water well. yard, pesticide anddiverted from well. fertilizer mixing

area, fuel storage or farm dump reaches well.

Separation Meets or exceeds Meets most minimum Meets minimum Does not meet alldistances between all state minimum separation distances. separation distances minimum separa-well and farmstead required separation only for sources tion distances forcontamination distances. required to be at least sources required tosources 150 feet from well. be at least 150 feet

from well.

Soil and/or sub- Fine-textured soils Medium-textured soils Coarse-textured soils. All soils if water surface potential (clay loams, silty (silt loam, loam). Water table deeper table shallower than to protect ground clay). Water table Water table deeper than 20 feet. 20 feet.water deeper than 20 feet. than 20 feet.

Condition of No holes or cracks. No defects visible. No holes or cracks Hole or crackscasing, well cap Cap tightly secured. Well vented but not visible. Cap loose. No visible. Cap loose or(seal) and slab Screened vent. Slab screened. Slab is slab present. missing. Can hear

is present. present. water running.

Casing depth Cased to the bottom Cased below water Cased to water level Cased above waterof the well. level in the well, but in the well. level in the well, or

not to the bottom. no casing.

Casing height More than 12 inches 8 to 12 inches above At grade or up to 8 Below grade or inabove land surface above grade or 2 grade. inches above. pit or basement or

feet above average less than 2 feetflood level. above average flood

level.

Well age Less than 20 years 21 to 40 years old. 41 to 60 years old. More than 60 yearsold. old.

Well type Drilled and complet- Drilled. Driven-point (sand Dug well.ed in accordance point*).with TNRCCstandards.

Condition

Location

Glossary

Abandoned well: A well that has not beenused for 6 consecutive months and is cappedand not deteriorated.

Air gap: An air space (open space) betweenthe hose or faucet and liquid level, repre-senting one way to prevent backflow of liq-uids into a well or water supply.

Anti-backflow (anti-backsiphoning) device:A check valve or other mechanical device toprevent unwanted reverse flow of liquidsback down a water supply pipe into a well.

Aquifer: A stratum or zone beneath the sur-face of the earth capable of producing water,as from a well.

Backflow: The unwanted reverse flow of liq-uids in a piping system.

Backsiphonage: Backflow caused by forma-tion of a vacuum in a water supply pipe.

Capped well: Well covered with a cap thatprevents surface pollutants from enteringthe well and that can sustain at least 400pounds.

Casing: Steel or plastic pipe installed whiledrilling a well to prevent collapse of the wellbore hole and entrance of contaminants, andto allow placement of a pump or pumpingequipment.

Cross-connection: A link or channel betweenpipes, wells, fixtures or tanks carrying chem-ical solutions or contaminated water andthose carrying potable (safe for drinking)water. Contaminated water, if at higher pres-sure, can enter the potable water system.

Drilled wells: Wells not dug or driven, includ-ing those constructed by a combination ofjetting or driving. Domestic wells are nor-mally 4 to 8 inches in diameter.

Driven-point (sand point) wells: Wells con-structed by driving assembled lengths ofpipe into the ground with percussion equip-ment or by hand. These wells are usuallysmaller in diameter (2 inches or less), lessthan 50 feet deep and can be installed inareas of relatively loose soils, such as sand.

Dug wells: Large-diameter wells often con-structed by hand.

Ground water: Subsurface water in anaquifer.

Drinking Water Well Condition: Assessing Drinking Water Contamination Risk

Low Risk Low-Moderate Risk Moderate-High Risk High Risk

Backflow Anti-backflow Anti-backflow devices No anti-backflow No anti-backflowprevention devices (such as installed on some devices. Air gap devices. Air gap not

check valves) faucets with hose maintained. maintained. Crossinstalled on all connections. connectionsfaucets with hose between waterconnections. No supplies.cross connectionsbetween watersupplies.

Unused well No unused, Unused wells capped Unused, unsealed Unused, unsealedunsealed wells. and protected. well in field. Exceeds well in farmstead.

minimum required Does not meetseparation distances. required separation

distances.

Water testing Consistent satis- Occasional deviation Bacteria, nitrate and No water testsfactory water quality. from standards with other tests mostly do done, or water dis-Bacteria, nitrate and bacteria, nitrate and not meet standards. colored after rain-other tests meet other tests. storms or noticeablestandards. changes in color,

clarity, odor or taste.

Management

Grout: Slurry of cement or clay used to sealthe space between the outside of the wellcasing and the bore hole, or to seal an aban-doned well.

Milligrams per liter (mg/l): The weight of asubstance measured in milligrams containedin one liter. One mg/l is equivalent to 1 partper million in water measure.

Parts per million (ppm): A measurement ofconcentration of one unit of material dis-persed in one million units of another.

Water table: The upper level of ground waterin a zone of saturation. It fluctuates with cli-matic conditions on the land surface andwith aquifer discharge and recharge rates.

Well cap (seal): A device used to cover thetop of a well casing pipe.

Well plugging: An absolute sealing of the wellbore.

Contacts and References

General information concerning groundwater flow direction and water quality can beobtained from:

★ Texas Water Development Board GroundWater Data Unit at (512) 445-1484, Officeof Water Resources Management,

★ TNRCC Agricultural Division Water WellDrillers Team Environmental Assessment,Division Ground Water Protection, (512)239-1000,

★ Office of Administration InformationResources, Customer Service for Drillers’Reports,

★ Texas Agricultural Extension ServiceAgricultural Engineering unit (409) 845-7451,

★ Texas Agricultural Extension Service WaterQuality unit, (409) 845-0887,

★ TEX*A*Syst homepage internet addresson the World Wide Web: http://waterhome.tamu.edu,

★ Texas State Soil and Water ConservationBoard, (817) 773-2250.

TEX*A*Syst is a series of publications to help rural residents assess the risk of ground water pollution, and to describeBest Management Practices (BMPs) that can help protect ground water. The TEX*A*Syst documents were developedfrom the national Farm*A*Syst ground water protection program. The TEX*A*Syst system is designed to help the userlearn more about the environment, existing environmental policies and regulations, and recommended managementpractices. Thus, the user can voluntarily reduce the pollution risks associated with water wells.

TEX*A* Syst materials were edited by Anna Schuster Kantor, and reviewed by M.C. Dozier and the personnel of theUSDA-Natural Resources Conservation Service, U.S. Environmental Protection Agency, Texas Department ofAgriculture, Texas Natural Resource Conservation Commission, Texas Water Development Board, Texas State Soil andWater Conservation Board, Texas Water Resources Institute, and Texas Farm Bureau. Editorial and formatting assis-tance were provided by the Department of Agricultural Communications, The Texas A&M University System.

The TEX*A*Syst program is sponsored by the U.S. EnvironmentalProtection Agency under Section 319(h) of the Clean Water Act.Funds for this program are administered by the Texas State Soil andWater Conservation Board’s Agricultural/Silvicultural NonpointSource Management Program.