Assessing the Risk of Groundwater Contamination From Pesticide Storage and Handling

Farm•A•Syst: Farmstead Assessment System Worksheet #2
Included when you order this worksheet: MU publication EQ676, Reducing the Risk of Groundwater Contamination by Improving Pesticide Storage and Handling, the fact sheet that corresponds with this worksheet.

Table 1
Pesticide storage and handling: Assessing drinking-water contamination risk

  • Use a pencil. You may want to make changes.
  • For each category listed on the left that is appropriate to your farmstead, read across to the right and circle the statement that best describes conditions on your farmstead. (Skip and leave blank any categories that don't apply to your farmstead.)
  • Then look above the description you circled to find your "rank number" (4, 3, 2 or 1) and enter that number in the blank under "your rank."
  • Directions on overall scoring appear at the end of the worksheet.
  • Allow about 15 minutes to 30 minutes to complete the worksheet and figure out your risk ranking for well-management practices.
 Low risk, rank 4Low to moderate risk, rank 3Moderate to high risk, rank 2High risk, rank 1Your rank
Pesticide storage
Amount storedNo pesticides stored at any time.Less than 1 gallon, or more than 10 pounds of each pesticide.More than 1 gallon, or more than 10 pounds of each pesticide.More than 55 gallons, or more than 550 pounds of each pesticide. 
Location of pesticide storage area in relation to well300 feet or more downslope from well.50 to 300 feet downslope from well.150 to 150 feet downslope from well.1Within 50 feet or up-slope from well.1 
Leachability (See Pesticide chart.)

Liquid or dry formulation
No pesticides stored.


No liquids. All dry.
Pesticides classified as having low leaching potential.

Some liquids. Mostly dry.
Pesticides classified as having medium leaching potential.
Mostly liquids. Some dry.
Pesticides classified as having high leaching potential.

All liquids.
 
Spill or leak control in storage areaImpermeable surface (such as concrete), does not allow spills to soak into soil. Curb installed on floor to contain leaks and spills.Impermeable surface with curb installed has some cracks, allowing spills to get to soils. OR impermeable surface without cracks, has no curb installed.Permeable surface (wooden floor), has some cracks. Impermeable surface, has no curb. Spills could contaminate wood or soil.Permeable surface (gravel or dirt floor). Spills could contaminate floor. 
ContainersOriginal containers clearly labled. No holes, tears or weak seams.Original containers old. Labels partially missing or hard to read.Containers old but patched. Metal containers show signs of rusting.Containers have holes or tears that allow chemicals to leak. No labels. 
SecurityFenced or locked area separate from all other activities.Fenced area separate from most other activities.Open to activities that could damage containers or spill chemicals.Open access to theft, vandalism and children. 
Mixing and loading practices
Location of well in relation to mixing/loading area with no curbed and impermeable containment area150 feet or more from well.100 to 150 feet downslope from well150 to 100 feet downslope from well,1or 100 to 500 feet upslope.Within 50 feet downslope, or within 100 feet upslope from well.1 
Mixing and loading pad (Spill containment)Concrete pad with curb keeps spills contained. Sump allows collection and transfer to storage.Concrete pad with curb keeps spills contained. No sump.Concrete pad with some cracks keeps some spills contained. No curb or sump.No mixing/loading pad. Permeable soil (sand). Spills soak into ground. 
Backflow prevention on water supplyAnti-backflow device installed or 6-inch air gap maintained above sprayer tank.Anti-backflow device installed. Hose in tank above waterline.No anti-backflow device. Hose in tank above waterline.No anti-backflow device. Hose in tank below water line.2 
Water sourceSeparate water tankHydrant away from well.Hydrant near well.Obtained directly from well. 
Filling supervisionConstant supervisionFrequent.Seldom.Never. 
Handling systemClosed system for all liquid and dry product transfers.Closed system for most liquids. Some liquid and dry product hand poured. Sprayer fill port easy to reach.All liquids and dry product hand poured. Sprayer fill port easy to reach.All liquids and dry product hand poured. Sprayer fill port hard to reach. 
Sprayer cleaning and rinsate (rinse water) disposalSprayer washed out in field.Sprayer washed out on pad at farmstead. Rinsate used in next load and applied to labeled crop.Sprayer washed out at farmstead. Rinsate sprayed less than 100 feet from well.Sprayer washed out at farmstead. Rinsate dumped at farmstead or in field.2 
Container disposal
Disposal locationTriple-rinsed containers returned to dealers or taken to licensed landfill or municipal incinerator. Bags returned to supplier, or hazardous waste collection service used.Unrinsed containers and empty bags taken to licensed landfill, municipal incinerator or dump.Disposal of unrinsed containers or empty bags on farm. Disposal of triple-rinsed containers on farm.Disposal of partially filled plastic or paper containers on farm. Bags buried in field or burned on farm. 
1Illegal for new well installation. Existing wells must meet separation requirements in effect at time of construction.
2Besides representing a higher-risk choice, this practice also violates Missouri law.

Why should I be concerned?

Pesticides are showing up where they're not wanted — in our drinking water. If pesticides are not handled carefully around the farmstead, they can seep through the ground after a leak or spill, or they can enter a well directly during mixing and loading.

Pesticides play an important role in agriculture. They have increased farm production, and they have enabled farmers to manage more acres with less labor.

Pesticides work by interfering with the life processes of plants and insects. Pesticides also may be toxic to people. If pesticides enter a water supply in large quantities — as can happen with spills or backsiphonage accidents — acute exposure (toxic effects apparent after only a short period of exposure) can range from moderate to severe, depending on the toxicity of the pesticide and the amount of exposure. Contaminated groundwater used for drinking-water supplies may result in chronic exposure (prolonged or repeated exposure to low doses of toxic substances), which may be hazardous to people and livestock.

When found in water supplies, pesticides normally are not present in high-enough concentrations to cause acute health effects, which can include chemical burns, nausea and convulsions. Instead, they typically occur in trace levels, and the concern is primarily for their potential for causing chronic health problems from prolonged exposure.

Your drinking water is least likely to be contaminated if you follow appropriate management procedures and properly dispose of wastes in a location that is off the farm site. However, proper offsite disposal practices are essential to avoid risking contamination that could affect the water supplies and health of others.

How will this worksheet help me protect my drinking water?

It will take you step by step through your pesticide handling, storage and disposal practices.

  • It will rank your activities according to how they might affect the groundwater that provides your drinking-water supplies.
  • It will provide you with easy-to-understand rankings that will help you analyze the "risk level" of your pesticide handling, storage and disposal practices.
  • It will help you determine which of your practices are reasonably safe and effective and which practices might require modification to better protect your drinking water.

How do I complete the worksheet?

Follow the directions at the top of the next chart. It should take you about 15 to 30 minutes to complete this worksheet and figure out your ranking.

Pesticide Leachability Chart

The pesticides listed on this chart are identified by brand name, common name and rating for movement by leaching (low, medium or high). Identify the pesticides stored on your farmstead from the listing below. Note the "leachability factor" for each pesticide you store. Then give yourself an overall "leachability ranking" (low, medium or high), based on which ranking best represents the pesticides you store. Then use this ranking to complete the "Leachability" section on the assessment worksheet.
Herbicides
Brand nameCommon nameRating for movement by leaching
Alanapnaptalam 
Allymetsulfuron-methyl 
Amibenchloramben 
AmitrolTamitroleMed
Antordiethatyl-ethylLow
ArsenalimazapyracidHigh
ArsenalimazapyramineHigh
AssertimazethabenzHigh
Assurequizalofop ethylLow1
AtrazineatrazineHigh
AvengedifenzoquatLow
BalanbenefinLow
BanveldicambaHigh
BasagranbentazonHigh
Betamixphenmedipham and desmediphamLow
Low
BetanexdesmediphamLow
Bicepmetolachlor and atrazineMed
High
BladexcyanazineMed
BlazeracifluorfenMed
Bronatebromoxynil and MCPA esterLow
Low
Broncoglyphosate and alachlorLow
Low
Buckletriallate and trifluralinLow
Low
BuctrilbromoxynilLow
Buctril-Atrazinebromoxynil and atrazineLow
High
Butyrac 2002,4-DB amineMed1
Butyrac2,4-DB esterLow1
Cannonalachlor and trifluralinMed
Low
Carbynebarban 
CasorondichlobenilHigh
Classicchlorimuron 
Cobralactofen 
CommandclomazoneMed
Commencetrifluralin and clomazoneLow
Med
Crossbowtriclopyr and 2,4-D esterMed
Low1
Curtailclopyralid and 2,4-D amineHigh
Med
CurtailMclopyralid and MCPA esterHigh
Low
DacthalDCPALow
DowpondalaponHigh
DualmetolachlorMed
EptamEPTCMed
EradicaneEPTCMed
Eradicane ExtraEPTCMed
EvikametrynMed
ExtrazineIIatrazine and cyanazineHigh
Med
Far-GotriallateLow
Fusilade 2000fluazifopLow
Galaxiebentazon and aciflourfenHigh
Med
GenatePlusbutylateMed
GenepEPTCMed
Gleanchlorsulfuron 
GoaloxyfluorfenLow1
Gramoxone ExtraparaquatLow
HarmonyDPX-M6316 and Extra DPX-L5300 
Herbicide 273endothallLow
HoelondiclofopLow
KerbpronamideLow
KrenitefosamineLow
Laddockatrazine and bentazonHigh
High
Lariatalachlor and atrazineMed
High
Lasso ECalachlorMed
Lasso Micro Techalachlor 
LassoIIalachlorMed
Lasso- Atrazinealachlor and atrazineMed
High
LexonemetribuzinHigh
LoroxlinuronMed
LoroxPluslinuron and chlorimuronMed
-
Marksmandicamba and atrazineHigh
High
MCPA AmineMCPA amine 
MCPA EsterMCPA esterLow
NortronethofumesateHigh
OptionfenoxapropLow
PinnacleDPX-M6316 
Poastsethoxydim 
PramitolprometonHigh
Previewmetribuzin and chlorimuronHigh
-
PrincepsimazineHigh
ProwlpendimethalinLow
Prozinependimethalin and atrazineLow
High
Pursuitimazethapyr 
Pursuit Plusimazethapyr and pendimethalin-
Low
PyraminpyrazonHigh
RamrodpropachlorLow
Ramrod- Atrazinepropachlor and atrazineLow
atrazineHigh
RangerglyphosateLow
ReflexfomesafenHigh
Rescuenaptalam and 2,4-DBMed1
Rhinobutylate and
atrazine
Med
High
Ro-NeetcycloateMed
RoundupglyphosateLow
Salutemetribuzin and trifluralinHigh
Low
Scepterimazaquin 
SencormetribuzinHigh
SinbarterbacilHigh
SonalanethalfluralinLow
SpiketebuthiuronHigh
Stampede CMpropanil and MCPA esterLow
Low
StingerclopyralidHigh
Stormbentazon and acifluorfenHigh
Med
SurflanoryzalinLow
Sutan+butylateMed
Sutazine+butylate and atrazineMed
High
2,4-D amine2,4-D amineMed
2,4-D ester2,4-D esterLow1
TandemtridiphaneLow
ThistrolMCPB 
TillampebulateMed
TordonpicloramHigh
TreflantrifluralinLow
Turbometolachlor and metribuzinMed
High
VelparhexazinoneHigh
VernamvernolateLow
WeedarMCPA amine 
Weedmasterdicamba and
2,4-D amine
High
Med
Weedone- 2,4-DPdichlorprop ester-
Low1
WhipfenoxapropLow
Insecticides
AmbushpermithrinLow
Aqua8-ParathionparathionLow
AsanaXLesfenvalerateLow
BolstarsulprofosLow
BroottrimethacarbLow2
CarzolformetanateLow
CounterterbufosLow
CygondimethoateMed
CythionmalathionLow
DiazinondiazinonMed1
DimilindiflubenzuronLow
DiSystondisulfotonLow
DyfonatefonofosMed
DyfonateIIfonofosMed
DyloxtrichlorfonHigh
EndocideendosulfonLow
Endocide Plusendosulfon and parathionHigh
Low1
Forcetefluthrin 
FuradancarbofuranHigh
Guthionazinphos-methylLow
ImidanphosmetLow
Knox-OutdiazinonMed1
LannatemethomylHigh
LarvadexcyromazineHigh1
LarvinthiodicarbLow
LindanelindaneMed
LorsbanchlorpyrifosLow
MalathionmalathionLow
Malathion/ methoxychlormalathion and methoxychlorLow
-
MavrikfluvalinateLow
Metasystox-Rdemeton-s-methylHigh2
Methoxychlormethoxychlor 
MitacamitrazLow2
MocapethopropHigh
MonitormethamidophosHigh
NudrinmethomylHigh
OrtheneacephateLow
ParathionparathionLow1
Penncap-Mmethyl parathionLow
PhosdrinmevinphosMed
PhoskilparathionLow1
PouncepermethrinLow
PydrinfenvalerateLow
RampartphorateLow
Scout-Xtratralomethrin 
SevincarbarylLow
SomanilmethidathionMed
SupracidemethidathionMed
Swatphosphamidon 
TemikaldicarbHigh
ThimetphorateLow
ThiodanendosulfanLow
TrigardcyromazineHigh1
VydateoxamylLow
Fungicides
Agsco TN-IVtin 
Agsco MNFmaneb and
zinc
Low2
-
BayletontriadimefonMed
BenlatebenomylHigh
Blitexmaneb and triphenyltinLow2
BotrandicloranLow2
BravochlorothalonilLow
CaptancaptanLow
CarbamateferbamMed
Championcopper-fixed 
CrotothanedinocapLow2
CyprexdodineacetateLow2
DaconilchlorothalonilLow
DithanemancozebLow
Dutertin 
DyreneanilazineLow
KarathanedinocapLow2
KelthanedicofolLow2
Kocidecopper hydroxide 
Magneticsulfur 
ManebmanebLow2
Maneb andmaneb andLow2
Zinczinc 
ManzatemancozebLow
Merteckthiabendazole 
OrbitpropiconazoleMed2
PenncozebmancozebLow
PolyrammetiramLow2
Protexmaneb triphenyltinLow2
RidomilmetalaxylHigh
RonilanvinclozalinLow2
RovraliprodioneLow1
RubiganfenarimolHigh
SuperSixsulfur 
SuperTintin 
TeloneIIdichloropropeneMed
TerrachlorPCNBLow1
TersanbenomylHigh
ThatFsulfur 
Thioluxsulfur 
TiltpropiconazoleMed2
TopCopbasiccoppersulfate 
TopsinthiophanatemethylLow2
Triphenyl Tintriphenyltin 
Hydroxidehydroxide 
TripleTintriphenyltin hydroxide 
VitavaxcarboxinLow
Vorlexdichloropropene and
methyl-isothiocyanate
Med
Med
1The rating is an estimate, but reasonably accurate compared to estimated ratings footnoted with a 2.
2The rating is a guess, and subject to a higher degree of error than estimates footnoted with a single asterisk.
Adapted from Becker, R.L., et al. 1990, Pesticides: Surface Runoff, Leaching, and Exposure Concerns. Minnesota Extension Service. Data were derived from U.S. Department of Agriculture SCS/ARS Pesticides Properties Data Base, Version 1.9, August 1989, developed by R.D. Wauchope et al., and ratings derived by D.W. Goss.
Chart modified annually. Contact your Natural Resources Conservation Service (NRCS) or local MU Extension center for the most recent version.

What do I do with these rankings?

Step 1
Begin by determining your overall well management risk ranking using Equation 1.

Total the rankings for the categories you completed, and divide by the number of categories you ranked:

Equation 1

________divided by________equals________
(total of rankings) (number of categories ranked) (risk ranking1)
1Carry your answer out to one decimal place.
If your risk ranking isYour risk is
3.6 to 4low
2.6 to 3.5low to moderate
1.6 to 2.5moderate to high
1 to 1.5high

This ranking gives you an idea of how your well management practices as a whole might be affecting your drinking water. This ranking should serve only as a general guide, not a precise diagnosis. Because it represents an average of many individual rankings, it can mask any individual rankings (such as 1s or 2s) that should be of concern. (Step 2.)

Enter your well management risk ranking above in the first table in Worksheet #9 (MU publication WQ659). Later you will compare this risk ranking with other farmstead-management rankings. Worksheet #8 (MU publication WQ658) will help you identify your farmstead's site conditions (soil type, soil depth and bedrock characteristics), and Worksheet #9 (MU publication WQ659) will show you how these site conditions affect your risk rankings.

Step 2
Look over your rankings for individual activities:

  • Low-risk practices (4s)
    ideal; should be your goal despite cost and effort
  • Low- to moderate-risk practices (3s)
    provide reasonable groundwater protection
  • Moderate- to high-risk practices (2s)
    inadequate protection in many circumstance
  • High-risk practices (1s)
    inadequate; pose a high risk of polluting groundwater

Regardless of your overall risk ranking, any individual rankings of "1" require immediate attention. Some concerns you can take care of right away; others could be major — or costly — projects, requiring planning and prioritizing before you take action.

Find any activities that you identified as 1s and list them under "High-Risk Activities" in Worksheet #9 (MU publication WQ659).

Step 3
Read Fact Sheet #1 (MU publication EQ675), Improving Drinking-Water Well Conditions, and consider how you might modify your farmstead practices to better protect your drinking water.

Glossary

These terms may help you make more accurate assessments when completing Worksheet #1 (MU publication WQ651). They also may clarify some terms used in Fact Sheet #1 (MU publication EQ675).

  • Abandoned water well
    A well that is permanently discontinued or that is in such disrepair that its continued use for obtaining groundwater is impractical or may be a health hazard.
  • Air gap
    An air space (open space) between the hose or faucet and water level, representing one way to prevent backflow of liquids into a well or water supply.
  • Anti-backflow (anti-backsiphoning) device
    A check valve or other mechanical device to prevent unwanted reverse flow of liquids back down a water-supply pipe into a well.
  • Aquifer
    A water-bearing formation (soil or rock horizon) that transmits water in sufficient quantities to supply a water well.
  • Bored wells
    Wells constructed using augers, scoops, drag lines or similar equipment. These holes are usually of large diameter and are constructed in alluvial or glacial material.
  • Casing
    An impervious durable pipe placed in a well to prevent the walls from caving and to seal off surface drainage or undesirable water, gas or other fluids to prevent them from entering the well.
  • Cross-connection
    A link or channel between pipes, wells, fixtures or tanks carrying contaminated water and those carrying potable (safe for drinking) water. Contaminated water, if at higher pressure, enters the potable water system.
  • Drilled wells
    Wells not dug or driven, including those constructed by a combination of jetting or driving. These wells are normally 4 to 8 inches in diameter.
  • Driven-point (sand point) wells
    Wells constructed by driving assembled lengths of pipe into the ground with percussion equipment or by hand. These wells usually are smaller in diameter (2 inches or less), less than 50 feet deep and can be installed in areas of relatively loose soils, such as sand.
  • Dug wells
    A well in which the side walls may be supported by material other than standard weight steel casing. Water enters a dug well through the sides and bottom.
  • Groundwater
    The water in the zone of saturation in which all of the pore spaces of the subsurface material are filled with water. The water that supplies springs and wells is groundwater.
  • Grout
    Slurry of cement or bentonite clay used to seal the annular space between the outside of the well casing and the bore hole. Also used in sealing abandoned wells.
  • Milligrams per liter (mg per liter)
    The weight of a substance measured in milligrams contained in 1 liter. It is equivalent to 1 part per million in water measure.
  • Parts per million (ppm)
    A measurement of concentration of one unit of material dispersed in 1 million units of another.
  • Pressure grout
    Refers to the process of applying grout material under pressure to the annular space of a well to seal it and thus prevent vertical movement of fluids through the annular space. Grout must be introduced from the bottom of the annular space.
  • Water table
    The upper level of groundwater in a zone of saturation. Fluctuates with climatic conditions on land surface and with aquifer discharge and recharge rates.
  • Well cap (seal)
    A method or device used to protect a well casing or water system from the entrance of any external pollutant at the point of entrance into the casing.
The Missouri Farmstead Assessment System is a cooperative project of MU Extension; College of Agriculture, Food and Natural Resources; and the Natural Resources Conservation Service.
The National Farmstead Assessment Program provided support for development of the Missouri program. These materials are adapted from the Wisconsin and Minnesota prototype versions of Farm•A•Syst.
This material is based upon work supported by the Extension Service, U.S. Department of Agriculture, under special project number 91-EHUA-1-0055 and 91-EWQI-1-9271.
Adapted for Missouri from material prepared by Susan Jones, U.S. E.P.A., Region V, Water Division, and University of Wisconsin Cooperative Extension.
MU Extension Farm•A•Syst team members: Joe Lear, Regional Agricultural Engineering Specialist and Chief Editor; Beverly Maltsberger, Regional Community Development Specialist; Robert Kelly and Charles Shay, Regional Agricultural Engineering Specialists; Thomas Yonke, Program Director, Agriculture and Natural Resources; Jerry Carpenter, State Water Quality Specialist; and Bob Broz, Water Quality Associate.
Technical review provided by August Timpe, Missouri Department of Natural Resources; Charles Fulhage, MU Department of Agricultural Engineering; U.S. E.P.A. Region VII, Environmental Sciences Division; and Missouri Natural Resources Conservation Service.