2113f2015 Prl~malll Science Feerures 

EUSGS 

science for s changing world 

The Quality of the Nation's Groundwater 

Thill Sciem:e Feature am be fOUDd at: hUp:llwww.usgs.gov/blogs/fcatURS!usgB top stmyfthc..quality-of-1he-nations-groundwatcr/ 

Categories: Featured. Wl1lm: - -

POIItcd on Jamwy 21, 2015 at 10:46 am By: Barbara Mahler, Jon CampbeD 

About 115 million peopl.o--mo.rc 1han ~1hird oflhe Nation's population-rely on groundwater fur drinkiDg water. As the Nation's population grows, 1he need fur 

high-quality drinking-water supplies becomes even mon: urgent. 

Groundwater--The Invisible and Vital Resource 

11 S Million People tefy ongroundwat@r for dnnklng wat« 

43 Million Pooplo rf!ly on groundwater I rom p~tv.lle Wl!lh 

1 of eve ry S Groundwater sampl~s 

from ptrb of aqulf«J uWid br li1nk1ng wilt« (Ont.lnld 

.a conumlnant from gcologk: or m.11nmade SOU lOIS o~t a~ 

e-xcMd1ng a potential human-Malth concern 

6,600Wells 

~~~edfotthl$$fudy 

1.1 Million Chemical Analyses 

porfonnod '"' th~ ltucly 

Oroundwatl=r -The Jnviaiblc and Vibll Rcso1m:c. Details: 

liS million people rely on groundwater fur drinldDs water. 

43 million people rely on groundwater from private wells. 1 

of every 5 grouDdwater samples from parts of aquifers used 

fur drinking watcr c:outaincd a c:ontaminant from pologic; or 

m1111made sources at a level exceeding a potential humanhealth c:mu:em. 6,600 wells were sampled fur 1hia study. 1.3 

million c:hemical analyses performed for this study. 

_] 

hUp:llwww .usgs4Pflblogs/falmeslpriramailf1post=208531 

"Through the WaterSMAR.T initiative and the Nlllional Water-Quality Aaaeasment Program, the 

Depimment of Interior is working to BOCUI'O sustainable water supplies of sufficient quantity and 

quality and to identifY measures needed to address cl.imatll clumge and future demands," llldd 

Jeunifer Gimbel, Principal Deputy Assistant Sea'etary of the U.S. Department of the IDterior. 

"The integrall:d work that USGS is cloing to map groundwater availability, groundwater quality, 

and 1he potential for contamination will give us the information we need to UDdmtarul natural 

and human effecta on groundwater and to take the action8 needed to protect this vital natural 

MSourec." 

The :recently completed national •mmmmy rePOrt of the quality of the Nation's groundwater is 

now available online. Nine associated report& (USGS circ:ulan) detail tegional-ICale aue&III!lel1t& 

of groundwater quality in about 30 of the most heavily used principal aquifers across the United 

Sbdl:a. 

A deep look at an unseen resource 

Over the last two decades, USGS scientist& have uaessed water quality in IIOURle (untreated) 

water from 6,600 wells iD extensive regional aquifers 1lurt supply most of the groundwater 

pmnped for the Nation's drinking water, irrigation. and other uses. This comprehensive 

aampliDg, alm~g with detailed infom!ation on geology, hydrology, geoc;hcmistry, and c:hcmic:al 

and water use. am be used to explain how and why aquifer vulnerability to contamination varies 

across the Nation. 

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2/1312015 Prl~alll Science F-*'• 

Exceedances of human-health benchmarks by one or more contaminants 

Columbia 

Plateau 

basin-fill 

Columbia 

Plateau 

basalt 

Willamette 

Basin and 

Range 

carbonate 

Central 

Valley 

Basin 

-. 

Basin and 

Range 

basin-fill 

0\ 

Hawaii~ volcanic 

Snake River 

Plain 

basalt 

lowlands 

CambrianOrdovician 

EXPLANATION 

Percentage of wells with o ne or more contaminant 

at a concentration greater than a human-health benchmark 

0 None 

D From geologic sources 

D From human sources 

New England 

crystalline 

All aquifers 

So/o 

\:::_) 

Wustmtion: Map llhowiDg many c:barts indicating "BxceedaDce& ofhuman-beallh beoohmarb by oDe or mcm~ contanrinauts"- For m1m1 chaila on exaa numbers, 

pleuo ndK to the liDbd MIOIIIIXlll in this lltOJy. 

National Findings 

• More tlwl one in five (22 pe~CC!~t) grol&lldwater samp!ea contained It lCMt one coniiiiDiaaDt at a ccmcelltration oi poCelltW coace:m for humaa. health. 

• Contamm•nt;a from geologic IIOUICCt--primarily m"''gg""*, anemic. alld ~for about 80 P=Qrt of C(tllfamjnant COIICCI!tratiOJU that~ 

a humall-health bencbmazk. N"ltrate, 'Which exceeded i1lll 1.-eadun•rlr in about 4 perce1rt ofwdls sampled, wu the Ollly coJUtituelrt from mnnwle 80al\lC8 dlat 

exceeded it8 humall-bulth beuchmark in mcm: thn 1 pm:eat of samplee. 

• DitfereDee8 in COiltaminmt COllCC!IIra1iou amona aquifers, within 1111 aquifer, arul even between two neatby weDs can be explaillecl by large- arullocal-ecale 

clifferalces in geology, hyclrology, geochemietry, 8lld chemical 8!14 water UBC. Ullderatlllding how D8IU!a1 featDre8 end human activities atfect poUildwater 

quality helpt 1D predict how end why aquiferw!Derability to contamillation variee aaou the Nldiou. 

• Hiah-volame pumpina ad ilription in many areas have profoadly dlanged. JfOUIIClwata" flow end quality. By 1DOVing shallow gt'OIIIIdwater deepet-, into 

parts of aquifers mecl for drinkillg wamr, iniption 8lld pumping have incrasecl the vuJnmoabilily of drinking-wamr supplies to contamination ftom l1ilrate, 

paticides, 8.lld other manmade cbemU:als fmm the land ll1lrlilce. 

• lnigation, hish-volume pumpillg, 8lld artificial mc:harge can cause cliffient type& of watms to mix, wilh the unexpecll!d ccmseqwmce of causing the aquifer 

rocks 8lld sediment to relealeutumlly 11CC11IJiD.s contaminants, sw:h as lllllllllic, aelaoium, or Jadinm. into tba groundwm£. 

Conccm1nJtions of clissolveclsolidl, chloride, 8.lld Di1IatD, iDdic:atonl of human iD1Iwmce on grol&lldwater qualily, i.ncmasecl from the 1990. to 2010 in llhallow 

grollllllwiMr in many parts of the Nalicm. Similar chatJges are likely to occur in deeps-puts of IOIJiellll.uifm-1 in the future as the shallow water moves clownwmt. 

Omundwatm-in ptmlllllble, unc:cmfiJied aquifin, sudl U tbll CenDBl Vlllley aquifer system in California, is especially vulnmable to c:cmtamination 
2/1312015 PrintEmaill Science F811bns 

Regional Principal Aquifer 

Assessments 

Jn..depth, regiooal~o asMSsmenb of grollll(lwater quality fuws on abou130 

of the !DOlt heavily U&ecl PriDcipal Aquifers in the Nation. Groundwater 

quality in 1hae aquifcn----end the factors that affect it-is described in Dine 

new U.S. Geological Survey cimllm~. 

Glacial Aq~~ifer System (northem U.S.) 

Wemmvntmriq (Dmthwestem U.S., Hawaii) 

Sou1hwest Basin-:till Aqyifm (sou1hwestem U.S.) 

Dexwer Buin Aquifer System (Colorado) 

PjedmOJ!t. Blue Rjclje. and Valley and Ri!JB Aquifcxs (eastem U.S.) 

Nor!hem Atlantic CrueT!!) Plain Surficial Aqy.ifer Sytrtem (east cout ofU.S.) 

UJmer Floridan AQuifer and ()yer]yiD& Swficial AgJ!ifq (southeutem U.S.) 

OudiDes of priDcipal aquifml of the U.S. For detail• on the map, pleue use the 

liDkedn:sources available in this story. 

Mississi&mi Jo:mbayment-Texas Coastal Uplpd Aquifer System and Mississ!&mi Riv« Valley A1luyial Aqyifer (SOU1heastem, southcentral U.S.) 

Hip plajpa Aquifer Sy&Wn (cen1ral U.S.) 

Looking forward 

Over 1ho next decade, about 2,300 sballow wells and 1,400 deep public-supply wells will bo sampled for a broad rango of water-quality coutitueDts as the National 

Water-Quality Auei8Dle:nt Plogrun continue• to add!eu the three CCDtral queationa: 

1. What is 1ho quality of1he Nation's groundwater, 

2. Ia it ptt:iDg better or WOllle, aad 

3. What factors affect 1he quality of1his vital resource. 

In the future, USGS-led natiooal and regioual scale mocleliDg will provide a 1hreo-dimeuioual pcrapective of1hc quality of the Nation's grouadwater tbat can be 

U&ecl to inform management clcci&ona. 

Learn more 

USGS National Snmmm Cjrcular. Quality q.ffire Nqtimz 's Growufwqtu Quality. 1991-2010 

R.eLtional re,pom (JUne) on principal aqgifm gfd!e u.s. 

NatiQ11al Wltet-Qwili\y Asseasmmt (NAWQA) Pmamm 

USGS GroundWl!ter Infurmation 

WaterSMART 

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