Nutrients in the Nation's Waters: Identifying Problems and Progress A Natlonal Water-Ouallty Asm?ssmm of Nutrients

U.S. Deprtmsnt ol the Interior US. GwIDgkml Suwey

Nubient pollution is not a new to fish, range from 0.1 milligmns problem. but it is among he most p r liter (mglt) under some wnditions persistent. Consequemly, the status to 2 mg/L undw others. of nutrients is one of The USEPA the h s t waterquality enforces a drink- issues waluatd by . When are nutrients a water ing-water &i&ird, the U.S. Geological qudity pmbleml or Maximum Con- Survey (USGS) Do problems exist everywhere taminant -1 National Water- or only in certain placesl (MCL), for nitrate Quality Assessment Ale getting bettm? underttte Safe (NAWQA) Pmg.nu-n. Ikinking Water

Public mncern To answer these questions, the lfdrinking about water pollution N*WQ* combine8 the water mtains ~romr nuhents prompt- best historical infonnatim with nimte m n c - n m - ed passage of the new data to arrive a~ at most titins in excess of Clean Water Act in wmprehensive -t of 10 m& it is 1972. Yet, more than nutrients available. consided unsafe 20 years later. the U.S. for human con- Environmental Fro- sumption. Indeed, teftion Agency (USEPA) reports that too much nitrate can cause "blue M y nutrients are still a waterquality syndrome" or methemoglobinemia pmblent the leading cause of This condition can cause death. degradation in lakes and estuaries, the particularly in infants. third leading cause of impairment in Sometimes, h e effects of too much rim, and the main -n why public nitrogen or phos$oms in water re- supply wells fail to meet USEPA s o u m s are quite visible: nutrient drinking-water standards. enrichment triggers a process called

eumphicarion that is marked by rapid When are nutrients a problem? algae growfh. Algae gmw into

~ 1 1 living things n& ,,imgen "blwms," form scum along the shore- d phosphoms, two of the most line of lakes, and emit foul odors as important numents. However, an plant matter decays. This decay. in excess of these nulrients can cause turn, depletes dissolved oxygen that two main t y p s of waterquality problems: dkgraded aquatic habitat a d polluted drinking water. In addition, economic and recre- ational problems, such as clogged incake pipes and waters Ihat are untit For swimming, can result.

Scientific guidelines rather than regulatory s u s are used to determine when too much niwate, ammonia or phmphate exists in aquatic habitats. These guidelines reflect the fact that 'h much" of any nutrient depends on more than just the amount; water ternmature and aciditv (DH~ are . ., . alsdfaaors, F~~ example, wmax- The effects of eumphicatbn on r~vers.

imum exposure criteria" for s t r e a m and bkes may be quite visibie Here, abae form a g m scum w the

ammonia, which can be very toxic Swke RWI war Buhl. 1 6 h o .

fish need to live. Drinking wates &%-I

from eutrophic sources may rreain f w l tastes and dm which, while not n e w w i l y harmful, degrade quality.

loo m M nlmte m ground water can render it uncbinltable. Near Gleelev. Colorsdo. residents purdwa M 6 d mtw

harm human heakh and pmm& wbrcrphruh. k u & t die dm easily but ncU degrade quicklfi nihte can h flush4 down togrwrsd wakrwmrkd

ahof of* rus, are &ly water-dubk a n d n o t m y n w b i l e k u r e ~ a d h e tosoilp&kles. Eroded d c a r r k s p f m p h a w r o ~ m s adlakewlleretheycancause eu+-.

I

The Land Use Connection

s 0

N h t e mnmtkfs BTB h'uhst in Wlow grwnd wasr in agrieuhlural a m

Am- and phoaphwua ccnamtraliwrs are h ~ h s s t downstream from urban o m

l o P 1 E a n a a ~ " r e f e r s t o b h e nountofanrrtrieotcm- ined in a &in d u r n o(

(for example, mlIIigram nitrate pw Ii).

. . . in domestic wells that are located in agticultuml mas. Fully 12 pemnt of sufh wells s a m p i d a c d d the MCL for aim. This txcsedrrnct rate is two fhws that of U d c wells in other land use stIhgs, md more thm six times highs than the rate of d a n c e in public apply wells.

. . . not in public supply web. Only ompuomtofpublicwellsexoeedthe

water standard. A h t 10 percent of m p h taken b u r b a n rivers and &cams haw ammonia W s grcaw than ''chronic exposum cribia'' for aquatic life. Phosphorus c o n c m m h m accssd in- stream limig - by the USBPA in 75 percent of urban simam mmpM and 25 percent of agricult~~ral mcams wopkd.

. . . in the first few wseks of evuy growirfK9tanon. SelsOnal highs a d lwrs . -

ai& M a Why? in ni& conomtra- Because wbk tiws resect lbe wpply &S tmd Risk factors for mtzuninahn cran be of Certilizer

dmte cmhmina- tion. Also, u d m heavy rains. I heSa fe~WaterAct . reguhr . . . i n w ~ ~ a t t h t b o t t o m o f mOnit4ringand prompt comtive d o n is ,gj,d drainagt basins, ~i~~~ and ~qaiRd i f p ~ b k 811pplis~ exctsd an Ma. -8 move state boundaries

. . . io rims and dowostrtam in hi? of large rivers. from agticulnual and urban -. Ammo- & tamid Points in oh and phqhrw wmahtions are basins may be highest htnam from a - due by accumulatsd nutrients. to sewage efnueat and d highest . . . n u in the Swtbeast, where the downhwn from agricultural a, owing large amwnt of w m d l d within the to mpoint d- A q d e c a 4 y m arc agicullural area a p p ~ to o f i k ~ the very &ti% to mbknls, tven nt concen- pru#mx of risk facwrs for nimte oomtami- tratiw well below tbt human Wg- nstioa (fig. 2).

Figum 2. Grwnd mi ntrate lwels are Ikhl M b~ highest where (1) h e wemi table u less lhnn 100 fael deep 12) 8& we & b i d O nitwen inputs (like f e n i l i or m u r d are h i . (4) -htion dansily is high, and MI iw mi0 of woodland to Empland is Iw.

1 Are conditions getting better? I

Figure 3. W i n the C h a t t a b b e Ftiver h s t m r n from ArlamaGewg$,droppedbfmorethan50 psrwnl afWr warn qwliiy improvsmsnt dforts bspan.

Nationwide, nutrient lwds in stmans, rivers and lpolsrd water changed Iitde beiwem 1980 and 1989-pbpborur twels M i n e d slightly and nitrate levels remained -. local tm&, which may be more variable, are dicult to a m s h s e h i i c a I data are often missing.

k~. A p t t C r I I of declkdiag phO@WU loads i n r i ~ d a w n s ~ 6 v m s e v e r a l u r b a u areas can be explained by resbictcd me of ~ h a t e i o ~ a n d m m e f f o M i v e ~ t o f w ~ w a t u . I n w t ~ , t h e amount of @cqhoms contained in tmted sewage efnuent coaning h n Atlanta, w * ~ b y 8 3 ~ i n 4 m (1989-83). USClS that Ihe amount of p h q h r u s in ltre Chsttahoochee R i w fell by 53 y t as a d t (a 3).

Yras. I n D a l l a s , T e x ~ a n d o i n e ~ u r b m arcas w h enbanwmPnts in w a g e k a l e ment w m kgun in mt 1970's and I W s , ~ t r e a m a m m w i a o o l s c e ~ ~ l l ~ h e m. T h e I3hmmm. wbicb involve b m s f d n g ammonia to drab?, makcefilueotlesstoxicmfisb,htmaynot molve pmblems of wwphication. Why? 3ccausc total amwnt of nitrogen in IhB water ~ m a i e s &e same, despite the change inform

M q k In swetal agricuttural - (see irtsu. right). nitrate ledr in Istreams and rivers gemau.y.yinaca9ed fouowiog in- crcms in f a the r use and decreased folkwing dec-s in fenilk use. Brosiw comQ1. duced tillage prm ice nuaient management, aud other best muagemeat practices (Em) cau Poteotjally affs* water quality. Howem, it is noI clar whether BMPB have overall led to impmvsd waw quslity.

many " C X ~ (failures to meet a dmkhg water MU) in public supply wells. Does this meao ground-- m a n a g e m 8iTorlSmRW~tlg?NOd mcmarily. 'Zhese deep wells may be mpping into "old" wa- mufhasSOy~a~oId.The bmetitsofmkiq nimgm use W y m a y n o t ~ w i d e n t f o a -Y m.

Channels and tims used to remwe m a r from fields and wst~res B(io a i ~ ~ n nJhients into w a t ~ m 8 ~ s Nitrate and m p n a t e I h O t rrmw a m s v e e m can

l1n~.lrry I.>onLrr, urcd as c'op fcrll lzcr o' storerl a s ~ c s n b e a s w ' k % d a n n i m i i d ~ t o wnd wata and atreama

- - About NAWQA

quality of the Nation's water remums Iuneinsd inconclusive. In re-

mtf, N A w Q A h g m l U.S. G s o l o ~ swey 413 N 1 d Ccata, RMo& VA 20192 --orgo& b t & J ~ . ~ a s g a g w I t i a w q ~

-by E l i d e t h A. Gr& Dm& R. HeLtdl, andDavid K. Muelkr

ThismprtLswon: BaUagljn, W.A.. GwW, DA., d Cwpe. RH.. 1843.

~ ~ a m d m n s p a t d ~ c u l D u r l ~ c a l s h the W i Rim 1991-Jr;l. in Sels*sd papers or^ ~ ~ I n b ~ a c r ~ o b r n c Midoonlilmtnl Uldred $taMS: U.S. -Opm-W--l~p~-

MmUOI, D.K. Hamika~, PA., Hclscl. D.R.. Hit& KI., ad Ruddy, B.C., 1995, Nmimm in g m d wntm m d surFaEe water d tlba Umkd b h e d y & of data tluwgb 19Kk US. Ccdogical Slnvcy b r - ~ h w A @ i m s ~ 9 5 4 0 3 1 , 7 4 p

Mwlla, D.U., ad I-IehL DE, 1996, N a in Ihe Naiion's wm+w much of a g d US. ~ ~ ~ 1 1 ~ 6 r p P .

Puctctt. LJ., 1% Mwpoim and pint - of nihugu~ in d m watadds of the Unilcd Slates: u.s. &dogid s U v e y ~ R m l m 8 tvwi&a- riwsRqxxi 94-4001.9~.

~ m i f h . R A . . A l t m d a , R B . , a d ~ , E C I , 1993. ! h m m w a t a ~ i n t b ~ U n i t d ~ I m d e e o d s O f ~ ~ duringIbslP80's,hNmicQalwatgflrmmary 1 9 9 e 9 I - - H w & m d S - W Qbmy: US. cwogh l slawy w-smpply Pnper 2400.p~ Ill-140.

U . S . - R ~ d m A g u q , 1995,Nalio~l watsr plalily invmmry. 1m US. BwkmmnM ~ A g w c y S x s f u i v a S l u n m p r y .

NAWQA Program U .S. Geological Survey 41 3 National Center Reston, VA 201 92