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Description of the Hydrologic Cycle 

Precipitation 

Temperature 

Evaporation 

Streamflow 

This is an education module about the movement of water on the planet Earth. The module includes a discussion of water movement in the United 

States, and it a/so provides specific information about water movement in Oregon. 

The scientific discipline in the field of physical geography that deals with the water cycle is called hydrology It is concerned with the origin, distribution, 

and properties of water on the globe. Consequently, the water cycle is a/so called the hydrologic cycle in many scientific textbooks and educational 

materials. Most people have heard of the science of meteorology and many a/so know about the science of oceanography because of the exposure that 

each discipline has had on television. People watch TV weather personalities nearly evel}f day. Celebrities such as Jacques Cousteau have helped to 

make oceanography a commonly recognized science. In a broad context, the sciences of meteorology and oceanography describe parts of a series of 

global physical processes involving water that are a/so major components of the science of hydrology. Geologists describe another part of the physical 

processes by addressing groundwater movement within the planet's subterranean features. Hydrologists are interested in obtaining measurable 

information and knowledge about the water cycle. A/so important is the measurement of the amount of water involved in the transitional stages that occur 

as the water moves from one process within the cycle to other processes. Hydrology, therefore, is a broad science that utilizes information from a wide 

range of other sciences and integrates them to quantify the movement of water. The fundamental tools of hydrology are based in supporting scientific 

techniques that originated in mathematics, physics, engineering, chemistry, geology, and biology. Consequently, hydrology uses developed concepts from 

the sciences of meteorology, climatology, oceanography, geography, geology, glaciology, limnology (lakes), ecology, biology, agronomy, forestry, and other 

sciences that specialize in other aspects of the physical, chemical or biological environment. Hydrology, therefore, is one of the interdisciplinal}f sciences 

that is the basis for water resources development and water resources management. 

The global water cycle can be described with nine major physical processes which form a continuum of water movement. Complex pathways include the 

passage of water from the gaseous envelope around the planet called the atmosphere, through the bodies of water on the sur.face of earth such as the 

oceans, glaciers and lakes, and at the same time (or more slowly) passing through the soil and rock layers underground. Later, the water is returned to the 

atmosphere. A fundamental characteristic of the hydrologic cycle is that it has no beginning an it has no end. It can be studied by starting at any of the 

following processes: evaporation, condensation, precipitation, interception, infiltration, percolation, transpiration, r.unoff, and storage. 

The information presented below is a greatly simplified description of the major contributing physical processes. They include: 

EVAPORATION 

Evaporation occurs when the physical state of water is changed from a liquid state to a gaseous state. A considerable amount of heat, about 600 calories 

of energy for each gram of water, is exchanged during the change of state. Typically, solar radiation and other factors such as air temperature, vapor 

pressure, wind, and atmospheric pressure affect the amount of natural evaporation that takes place in any geographic area. Evaporation can occur on 

raindrops, and on free water sur.faces such as seas and lakes. It can even occur from water settled on vegetation, soil, rocks and snow. There is a/so 

evaporation caused by human activities. Heated buildings experience evaporation of water settled on its sur.faces. Evaporated moisture is lifted into the 

atmosphere from the ocean, land sur.faces, and water bodies as water vapor. Some vapor always exists in the atmosphere. 

CONDENSATION 
Condensation is the process by which water vapor changes it's physical state from a vapor, most commonly, to a liquid. Water vapor condenses onto 

small airborne particles to form dew, fog, or clouds. The most active particles that form clouds are sea salts, atmospheric ions caused by lightning, and 

combustion products containing sulfurous and nitrous acids. Condensation is brought about by cooling of the air or by increasing the amount of vapor in 

the air to its saturation point. When water vapor condenses back into a liquid state, the same large amount of heat ( 600 calories of energy per gram) that 

was needed to make it a vapor is released to the environment. 

PRECIPITATION 

Precipitation is the process that occurs when any and all forms of water particles fall from the atmosphere and reach the ground. There are two subprocesses that cause clouds to release precipitation, the coalescence process and the ice-crystal process. As water drops reach a critical size, the drop 

is exposed to gravity and frictional drag. A falling drop leaves a turbulent wake behind which allows smaller drops to fall faster and to be overtaken to join 

and combine with the lead drop. The other sub-process that can occur is the ice-crystal formation process. It occurs when ice develops in cold clouds or 

in cloud formations high in the atmosphere where freezing temperatures occur. When nearby water droplets approach the crystals some droplets 

evaporate and condense on the crystals. The crystals grow to a critical size and drop as snow or ice pellets. Sometimes, as the pellets fall through lower 

elevation air. they melt and change into raindrops. 

Precipitated water may fall into a waterbody or it may fall onto land. It is then dispersed several ways. The water can adhere to objects on or near the 

planet surface or it can be carried over and through the land into stream channels, or it may penetrate into the soil, or it may be intercepted by plants. 

When rainfall is small and infrequent, a high percentage of precipitation is returned to the atmosphere by evaporation. 

The portion of precipitation that appears in surface streams is called runoff. Runoff may consist of component contributions from such sources as surface 

runoff, subsurface runoff, or ground water runoff. Surface runoff travels over the ground surface and through surface channels to leave a catchment area 

called a drainage basin or watershed. The portion of the surface runoff that flows over the land surface towards the stream channels is called overland 

flow. The total runoff confined in the stream channels is called the streamflow. 

INTERCEPTION 

Interception is the process of interrupting the movement of water in the chain of transportation events leading to streams. The interception can take place 

by vegetal cover or depression storage in puddles and in land formations such as rills and furrows. 

When rain first begins, the water striking leaves and other organic materials spreads over the surfaces in a thin layer or it collects at points or edges. 

When the maximum surface storage capability on the surface of the material is exceeded, the material stores additional water in growing drops along its 

edges. Eventually the weight of the drops exceed the surface tension and water falls to the ground. Wind and the impact of rain drops can also release 

the water from the organic material. The water layer on organic surfaces and the drops of water along the edges are also freely exposed to evaporation. 

Additionally, interception of water on the ground surface during freezing and sub-freezing conditions can be substantial. The interception of falling snow 

and ice on vegetation also occurs. The highest level of interception occurs when it snows on conifer forests and hardwood forests that have not yet lost 

their leaves. 

INFILTRATION 

Infiltration is the physical process involving movement of water through the boundary area where the atmosphere interfaces with the soil. The surface 

phenomenon is governed by soil surface conditions. Water transfer is related to the porosity of the soil and the permeability of the soil profile. Typically, 

the infiltration rate depends on the puddling of the water at the soil surface by the impact of raindrops, the texture and structure of the soil, the initial soil 

moisture content, the decreasing water concentration as the water moves deeper into the soil filling of the pores in the soil matrices, changes in the soil 

composition, and to the swelling of the wetted soils that in tum close cracks in the soil. 
Water that is infiltrated and stored in the soil can a/so become the water that later is evapotranspired or becomes subsurface runoff. 

PERCOLATION 

Percolation is the movement of water though the soil, and it's layers, by gravity and capillary forces. The prime moving force of groundwater is gravity. 

Water that is in the zone of aeration where air exists is called vadose water. Water that is in the zone of saturation is called groundwater. For all practical 

purposes, all groundwater originates as surface water. Once underground, the water is moved by gravity. The boundary that separates the vadose and the 

saturation zones is called the water table. Usually the direction of water movement is changed from downward and a horizontal component to the 

movement is added that is based on the geologic boundary conditions. 

Geologic fonnations in the earth's crust serve as natural subterranean reservoirs for storing water. Others can a/so serve as conduits for the movement of 

water. Essentially, all groundwater is in motion. Some of it, however, moves extremely slowly. A geologic fonnation which transmits water from one 

location to another in sufficient quantity for economic development is called an aquifer. The movement of water is possible because of the voids or pores 

in the geologic fonnations. Some fonnations conduct water back to the ground surface. A spring is a place where the water table reaches the ground 

surface. Stream channels can be in contact with an unconfined aquifer that approach the ground surface. Water may move from the ground into the 

stream, or visa versa, depending on the relative water level. Groundwater discharges into a stream fonns the base flow of the stream during dry periods, 

especially during droughts. An influent stream supplies water to an aquifer while and effluent stream receives water from the aquifer. 

TRANSPIRATION 

.. 

. . 

Transpiration is the biological process that occurs mostly in the day. Water inside of plants is transferred from the plant to the atmosphere as water vapor 

through numerous individual/eave openings. Plants transpire to move nutrients to the upper portion of the plants and to cool the leaves exposed to the 

sun. Leaves undergoing rapid transpiration can be significantly cooler than the sunounding air. Transpiration is greatly affected by the species of plants 

that are in the soil and it is strongly affected by the amount of light to which the plants are exposed. Water can be transpired freely by plants until a water 

deficit develops in the plant and it water-releasing cells (stomata) begin to close. Transpiration then continues at a must slower rate. Only a small portion 

of the water that plants absorb are retained in the plants. 

Vegetation generally retards evaporation from the soil. Vegetation that is shading the soil, reduces the wind velocity. Also, releasing water vapor to the 

atmosphere reduces the amount of direct evaporation from the soil or from snow or ice cover. The absorption of water into plant roots, along with 

interception that occurs on plant surfaces offsets the general effects that vegetation has in retarding evaporation from the soil. The forest vegetation tends 

to have more moisture than the soil beneath the trees. 

RUNOFF 

Runoff is flow from a drainage basin or watershed that appears in surface streams. It generally consists of the flow that is unaffected by artificial 

diversions, storages or other works that society might have on or in a stream channel. The flow is made up partly of precipitation that falls directly on the 

stream , surface runoff that flows over the land surface and through channels, subsurface runoff that infiltrates the surface soils and moves laterally 

towards the stream, and groundwater runoff from deep percolation through the soil horizons. Part of the subsurface flow enters the stream quickly, while 

the remaining portion may take a longer period before joining the water in the stream. When each of the component flows enter the stream, they fonn the 

total runoff. The total runoff in the stream channels is called streamflow and it is generally regarded as direct runoff or base flow. 

STORAGE 

There are three basic locations of water storage that occur in the planetary water cycle. Water is stored in the atmosphere; water is stored on the surface 

of the earth, and water stored in the ground. 

Water stored in the atmosphere can be moved relatively quickly from one part of the planet to another part of the planet. The type of storage that occurs 
on the land sudace and under the ground largely depend on the geologic fe&tUIIiiS rr:Nated to the types of soil and the types of rocks present at the stomge 

locations. storage occurs as surfece storage in oceans, lakes, resetVoirs, and glaciers; underground stotage occurs in the soil, in aquifers, and in the 

crsvicas of rock fonnations. 

The movement of water through the eight other major physical processes of the water cycle can be erratic. On average, water the atmosphel& is rsnewed 

evety 16 days. Soil moisture is replaced about every year. Globally; waters in wetlands are replaced about evety 5 years while the residence time of lake 

water Is about 17 years. In 8f8BS of low development by society. groundwater 1811f1Wal can exceed 1, 400 yeat8. The uneven distribution and movement of 

water aver time. and the spatial distribution of water in both geographic and geologic a/9BS, can cause exf18111e phenomena such as floods and droughts 

to occur. 

ESTIMATED 

GLOBAL WATER CYCLE 

TYPE OF LOCATION VOLU!'IE PERCENT OF TOTAL 

WATER millions of millions of IIOLU!'IE 

cu. miles cu kilometer 

SALT WATER 97.88 

oc:eans 314.2 1388.8 (96.4:10) 

saline bodies 2.1 8.7 (8.61) 

FRESH WATER 2.98 

ice a snOIIil 6.9 28.7 (2.1S) 

lakes e.s 2.1 (8.15:10) 

rivers 8.81 8.84 (8.883:10) 

accessible 

aroundwater 1.8 4.2 (8.31:10) 

All'I)SPHERIC 8.18 

ua 

evaporation 8.1 8.42 (8.83:10) 

lond 

evaporation e.8s 8.21 (8.815:10) 

precipitation 

over sea 8.89 8.37 (8.83:10) 

pretipitation 

ovar land 8.83 8.12 (8.81:1:) 

water vapor 8.885 8.82 (8.882:10) 

ROI.INOED TOTAL 326.88 1357.88 188.8 

If a ftfty..five gallon drum of water f9fJ19Senled the total supply of water on the planet then: 

ll) the oceans would be represented by 53 gallons, 1 qu.rt, 1 pint and 12 ounces; 

b) the i_,a Mid glaci81S would ,_., 1 gallon, Mid 12 ounC811; 

c) the afmosph- would contribute 1 pint and 4.5 ounces; 

d) groundMitw would add up to 1 quart •nd 11.4 ounces; 

e) livshwafar leku would,_., one helf ounc.; ~ Inland seas and salina lalru would add up to ovar one fllln1 of an ounce; 

g) 11011 mol.ture Mid valdotJe wafar would (Otll to eout one fourth of •n ounce; 

h) the rivflnl of file world would only add up to one-hundnJdth of an ounce (less fll•n one OllfHIJillionfll of the wafar on file pltme#J. 

WATER BUDGET IN THE UNITED STATES 

The atmosphel& above the 48 coterminous United States of America stores about 36.5 cubic miles per day of atmospheric water. A little over 10 pe!CfN1t 

or 3.9 cubic miles of it falls as precipitation each day. About 1,430 cubic miles of precipitation fall aver the 48 states annually. This volume would be 

enough each year to caver the states with about 30 inches of water. 

The gmatest avenrge yearly precipitation In the wolfd of 460 Inches (1, 168 em) occurs at Mt. Walalea/e, Hawaii. The lowest average annual precipitation 

of 1. 63 inches ( 4. 1 em) in the United states occurred aver a 42-year period in Death Valley, California. The longest dry period with no p!8Cipitation in the 

United States occurred during a 767 day period from October 3, 1912 to November 8, 1914 at Bagdad, Ca/ifomia. 

An evenrge of 70 percent of the annual precipitation to the coterminous U.S. ( 1,001 cubic miles) evaporates back into the atmosphers from land and 

water surfaces and by transpiration from vegetation. The T9trlaining 30 pe!CfN1t of the annual pi9Cipitation ( 429 cubic miles) is transported through the 

other sulface and subtemmean p!OCfiSSes of the water cycle to a sti9SITI, lake, or DCEISIJ. 

Groundwater storage in the cotenninous United States has been estimated to be about 15,100 cubic miles both in the shallow groundwater (less than 

2,600 feet deep) and an equal amount in the groundwater deeper than 2, 600 feet. Soil moisture in the top 3 feet of soil is estimated to be equivalent to 

about 150 cubic miles of water. 

The United states has approximately 4,560 cubic miles of water st018d in freshwater lakes. Although there at8 about 5, 540 cubic miles of water fW 

sto/ed in the Great Lakes alone, aver 50 percent of the volume is considered to be in the United States. Also, about 14 cubic miles are stored in salt 

lakes of the nation. In addition, there is approximately 12 cubic miles of surface waters strwd in stmam channels in route to the oceans. Other sowces of 

sulface storage in the coterminous states include 16 cubic miles of fTrJZsn water in glaciers. 

The stream flow volume that reach the oceens of the nation is about 1.12 cubic miles per day ( 409 cubic miles per~- The total combined surface and 

groundwater flow to the nation's oceans is 1. 18 cubic miles par day. The Mississippi River alone contributes 0. 34 cubic miles per day (annual natural 

runoff of 593,000 cubic feat per second). 

Thet8 are approximately 2700 reservoirs and controlled natUI8llakes of mora than 5, 000 acra-teat in st01age in the United states. The reservoirs provide 

142 cubic miles of storage, almost 90% of which occurs in 600 of the 1Sip68t rsservoirs. Also, them Elf9 approximately 50,000 res91Voirs ranging from 50 

to 5,000 ac1'6-leet in st01age. It is also estimated that there at8 about 2 million fatm ponds in the United States. Most of the major raservoirs in the nation 

fW owned by the public. The 8Uf81JU of Land Management is the manager of the most federal dams (over 750), but most are small dams. The larger 

resetVoirs are managed by the U.S. Army Corps of EngineetS, the Bunmu of Reclamation, and the Tennessee Valley Authority. The Corps has built and 
~ 8lmotst 600 d8m8 8lld l'8(ff1(Vf]/(3 ,th9 8U~VM~ d Reclamation~ nB6IIy 3(}() dsm8 8lld lfN1fJI'II'fJit, 8lld thfi1VA 11811 CMK 50 dsmlt l1!fld 

1fiiSfJMJils. Oth8r ffldtsrs/ IJ(1fNICifl8 thllt lll!i!ll!iSifl ~ dllmtt inclr.ld9 the US FctrHJt S8Mce with abclA 400, thfl&lllleu d lrdfln AffainJ with OVflf 300, the 

NaOonal PM< SeMt;e with CMK- thfl US Fillh end Wihlf& S8tvioo with OVfll' 115. and the Dei~Mment d En!NriY with &!boot 30 cMms.. 

WATER IN THE STATE OF OREGON 

Cll'eQIM iS dividtld into two d8fincll'liitlftlll ZCinfle by the Ceteeede Renge. n. tiMIJIJI precipbtion west of thfl c~ ~ ~ frrlm 40 to 140 

i1lcJio$. Eutdtht c~ ~ IWI9" frrlm 10 to 20itlchot/#YIIIIf. ~ ,...ftMIJ(II ~ fCI'ttt&ril'f-- it .28 ~ The 

WM198 atlllUIII Nnt1ff ;, ebod 21) ~- ~ etllffl n. a flfllwotfc cf 112.000 ~ d rivet'$ MtJ ~to eccommodftled the tlllfiiAI tuttCif. n.. 4W 

owr365 wal.elflll• fNPP(Idfn OlegQn thtrt twin the ~4lfldth&C(Qract ~ dwtdMftr/ls. ~ 'tlftiiiWfW!• htWfl ~ lfdtlnet otwat« 

w1tll ~ mcrtffllmtlllt dthfl ffc1Ning Wilt« clt81181tflocl8fed In a SUCC6'1Sion d stages. Clilllal&ct Clll8fJOIY wttlttdt11f/a hiN& l&tg& liMin8a d wafet 

that move ptllp8/)dkdl1ll O!l8r 129 geathtltm81 hot sptfnga In ttl& stat& hiiN'& be6ll kllilltlfled with 'lllllwfrimp&nlltiJf8& thllt 818 16 degtHa F llllxw& th& 

- #llliiU8/IIIrt&mp&nltiU18. Thfl lolfll ~«Supply In Clrll{jiM h8s not be6ll qlllllltlfled.. 

Cll'eQIM tw an $$llmttled ltll1.llll.llll fllllllJIJI S1M'fllce wattllr supply cl ()JI«' 66 m11t1011 ~-(t9.6 cdJic mlfea). ~ tn the -Ottlll811d 

{/flll(/f8/Jhlc cllrtrfbiAfon d III'Biw ~ tlltr:xJ(IIIJU the etat& 181lfits In antiUill Wflt6l' shiJrt&gf.l6 fn mtlllY 81881 d th& atat&, &&pliCI8IJy In MStam Clr8fpt 

US& d llllbnl flaw d a1Rt'ac6 WBIC~t'$, IWff8c& elOI'IIfl& In f9BfiiVO/ts, 8trd l1fXIKI WBhlr SlfJIJI/&6 ttom BqJif8fa 818 US8d to m&8l th& 'lf1llll' III10IJfrtJ tlllm8nds. 

ThflfJI8#0rltverlllr9c1ifVOtagon Is ttl& 1,243 mll&lollg Colllnbls RNer. n fatma much dOragon's notth&m boii:Jerwtth ttl&ststB dW8Siitlgton. One at 

ttl& Cdl.mbla's mB/lX tiRIIABife/J, ttl& Snske RlwK forms a fl1fi/OI' pottJon cf ttl& eastsm barl8r d Ol8goo with lcl&ho and Is th& loc8flon cl ttl& 7,900 I &at 

d&ep Hell's Canyon. Thfl Columbia RH6r otfg/11Bt8S In 8!tf«;ent st&t8S cl Washlllgton, Idaho, 8lld Mont- tlnd In C61111!d9. 111& 8VIII8fll& BIIIIUfll flow Is 

266,(](}()cUJic feetperftf~Cend. Thill volumfi~B 0.16C1Jblc mJ1e6 pet' day. 

Other major watersheds in Oregon can be divided into 2.0 additional basins. They include: 

IIOI"th Q)Gst Dl"81.,..es 

1111"-ttte 

senq 

DeschUtes 

Jolin Day 

~.~~at1Ua 

6tande IIOnde 

POWder 

snake 

Jllll.hell~ 

Jllll.hellr 

~ Lake' 

ICl-th 

Chetco 

Ro,.,e 

SoW. Q)Gst DN11131K 

l.'lpq~M 

!Ud-Q)Gst Drainaees 

~" ~ MltMheda thftt empty intO tht P6cific Ooten. Two dth& b8$RI$ rJ "~ btiBNl tlnd «*l not d~ Wf.llet to the OCMtl CtftO 

t&Cfivmg $hWN. B1111$t1818 iflt(llf()tf lmiM that ~ into I8CfiMttg $b8am$.. 

Cll'eQIM llbol.tntla wflh CMK6,lmnstU/'8IIflku, pondB, IIIIJ!I'Ilh8S,IIklu{IJB endl8fU.IIVOirs.. Over 1,40Datth8m 818 nsm&dhlket. Th&y hi!N&acomblned 

Sll1f8c4) 811111 of 6CIQ,lm 8CI8S {1fN .tqiJIII8 1111/&s). Hund18tiB of the lalr8S -1A11118171&d. 71ler&- 13 LDilt L.sk&a, 11 8lu& Lsk&a, 10 eta. l.Bic8S 8trd 10 

Fish L.M8s. Thfly f8fiiJ& fn Sl.l1f8t:6 8188 Biz& ftom a II'I8XImt.m c/90,000 actiiS (t41 ~mil&&) 8t Upper Klflmfllfl L.tlkfl to C8ltJ& pond, fetm pondB, 8trd 

mill ponds of l&ss tb8n 0118 8CI8. CIBI« l.Bicfl Is th& d8ep8st Isle& In the Ul'llled States. It Is 1,932 feet dNA wllh 8 C8p8tCfty at14 mHI/on ii!CI&-fe&t (4. 14 

cubic mllfls) lllld 8 siRfst:e SIN at13., 139 8C18S (20. 61ltlU818 miles). Fdlowlng hea1ly ra/nltJ/IIllld Nnt1ff du1ng In 1884, MBfh8ur 81/d Hllm&'f lakes In 

IJ4Uih8astBm Ol&goo-jolnfld togsth&r for B1IN&t8l y&atS. M8lltlwr L.ttk& end Hllm8f t.a1te 8/8 ags/11 S&p81111& hlk&a, but CCIIfi8Cted es part d a closed 

b8sJn Wfltl8nd systwn, wlthl.f8lh8ur I..Bk& b&lng about so,ooo actBS. 111& ltllalhflur l.ak& ccmplaK Is stm con&ld&t9d th& /arg8Bt nsfU/81 bor1J cf WBf« In 

()agon. Thfi1SO,lm8C18S (2Bf squBifl mll&s) cltheltllkfllw6fJtlnfi oomplflx loc8t&d In ttl&~basln forms th& IBI!l&at freBfNnlf«matShln the westam 

«11111guous United Slsl&a. 0/hBr l8rg& hikes In Clt8goo Jncludfl Watal, Odell, and Wallowillflkes. Mar& thfln hBif cl the lak8S In ttl& state 818 1IOicanlc or 

s;scJ8I dept&sslons /ocl/ltfld on ttl& high~- ~ttl& srmmii:S d ttl& Cascad& Rllll(lfl. NfiBify 100 of ttl& nBIUIBIIflkes - clustfll8d In the 

Walrow8 Mountfllns c1 notth&flsfam ~- MBny ot11« lak8S -locsbld ~sand <bl6lf ,_. th& ~ shoi8. Many of the ntllbnllak8s 

throughout thfl state htN& had wilt IN control sf.trlctrns built &t theiT outlets to eniJ8nc;e slofagflln ths 18ku 8lld to control thfllf1if1flsfJ of stmJd w&t8r for 

downstr8l.lm /tdg8tloo. 

01'8Q011 has motfl tflan tJO INfJMJirlt with c~ cl Wet' 5,(](}() 6CifHMt eech. Thfl ~ tf1flfNVCir In tflfl lttrfi 18 the &I!Mu at RflclameiJon'ft 

OtNyhtJe L.tlJrs In IJOlAhflutsJm ~with OVflf 1 mHI/on ~ ( o.3 cubic mllfls) ct ... Molrl of tflfll'68fJI!ffJirlt In Onlgon-built, et Mat 

~ 

petlielly. to siMI irri(1IJtion Wlbr. Thtw- hl.tndr8da d tJIMII ~ /lflfP08fl.ll'IIIWVOim IM1t by /ot:eJ inigeticn CCIIIIPIIIM Relwtypetg d ein(JHI J1411110" 

includ9 -I'Mtion ~. fiah end wihlihii1IIIIIIMllill, end wetrNqualq ~ l'fiBfiMirrt. 

RMIJI'IIOils 818 gll()fllf1/ly chMJt;tfllizfld by thfliri/Riflct putpOHIII. Water euppJy ~ M1 6atiflguillhfld by IQe IJtonlgfllfdtlnes that-~ d 

~an upectfld lltltiUSI eupply d Wl1ltPr end cepebl8 cl outJ8ating mot1t drctti;lt3. lnigation ~ lllllffllairlfl t:OMIIIVIlfion poo/3 with ITifiXimtm 

CCII1WVation 

~ 

pocls at thfl be(jnning d the llfOWing s-end a mmimum poe/~ ttl& lltJtlfJ7fJWinr- F1octl control~ hiN& a tJm8ll 

pocls wiffle ~ ltfotag$ ctPifCi6$s to l'lXIuce dowm!IMm watiJI' levels key loc«ions on rWerlt. A~hBr~ of flood control 

~iS thft tht1y" (I1JIW(IRy drt!Ntndcwn • qcicldy es ~ f'dlowing • hitlt fl.lll(}/f 4WMt to l'(ll)lflebfiah tflflir ~ c~tio&. A hy~ ~ia t;IIMt;ftiiztdiJylttQfllgtand~ptOpetti&$ tMt nlfft ~~~.~~the wiflletCtftht~ 

RtH'l1{1.18tion ~ " built l1thfl hydtotlitcttlc ~ to et81bitizeltlf(lt« f1ow in rivet'$ to ~ fk1w nuctCI/IItiOM ~ dtJiJy {10IIIIflf Qlllt*IWiolt 

period$. ~ ~ ~ fortWig8tion fNIPOIJCit /I(Wfl /at9fl .. f/CilJI$ at til& btl{jMillg d th& dty HIIIOII and th&y ~8 8tiOII(jl Wilt« 

to support tiNBOiltllllttlllgttllon frltfl1c. LDck and dflm tfiS11tVOita. "-er. ~~~ watfllflomfl fl&lllglltlon b:Y CIWIIng $lightly val)' pod$ that (f)d(III(J$ 

t.pStiNm • con&ld8t8lil& datflnC6 ttom th& tiJIH1f-ttvet' ptqects. 

US Army Cclps atE~ l'fi88IVdra 8ffl fllliiJpl& putpOB&/mpoUfldnl6nts meeting ~t)7les ofwlitfNI8SOOIC& n&fldB flf.ICh 8S floodconflrll, 

hyd/ofllflct11c pt1Wfll' g&ll&fflllon. nBIIIgst/on, ltrfgBtlotl. munlclptll4ltld lnd!lst1llll WfiiM sqpy. watiJI' qusllty. frsh&ll6s, and rectfl8tlon. Th& Pottlsnd D1Bf11ct., 

Caps d En{ln8sls buRl and op&lfll&a thl86 11111-d-ttv« f9BfiiVOI1s on ttl& main stsm cl the towel' Cdl.mbla Rftl&t; Bonnwflle, Thfl D8118S, 8fld John Dsy 

dilms, t11st mNt ll8ll1g8llon, llydtotM&ctlfc pl1Nf1t; fnfgBtfon, ffshfltffiS, Wflf« qut1llty and I8Ct88tlon ll8llds.. Thfl Pottland Dlsttfct 81110 has biMt 8lld op8fflt&a 

1311llilipl6 purposs 8ionlg8 pl0j8cta with s totBI c:t!p8CII:y cl2,308.020 8CI&fe8t ofwahlr 8t 1718Jtlmum COII/ltW'8tlon pool ( 0.68 cubic mJJa) In th& 

WJIIIJm8ttll Rlll8r Basin. Thfl dlatlfct 8ltl'o Bb8s w, t91li!Ct&-feet d WfiiM (il. 18 ciMc mile) 8t ttl& mmtJmum paola at th& two Rogu& Rlvflr &JsJn proJacJ;s.. 

Addltlon8lty. John Dsy 08m, on ttl& Colt.lmblfl Rlvfll; has 634,000 tK:t&/&at {0.16 cubic 1111186) cf ussbl& stotaga Pottland Dfsttfcf's 'N'fHtNI Cte6k Dtlm, on 

the nolth a111tm1 Onlgon trfblbly to th& Colutnbla Rlv8l; stOIN 6,249 8C1&-II1et {0.002 cubic m1181l) ell's 00111181 summ&rCOIISfiN8IIon poollfl'llfll. 

'7'hllnifonJ, the totslli'OIIRrle of watfN storfld In Pottlflnd DlsfJfct 18SSMltls Is eqliJ181Bnt to -76 pBIC&IIt atth& sin{/& d8l/y flow cl Wllll8r from U.S. 1Mits 

Into ttl& oceans. 

Th& sdJrKIIJing d wilt IN ltfon.lgl9 end lf1IMit& ftr;m dflmtt ht part cia W8tiJI' ,_ ~ ft.tnctlon ce/lf1d l'fl(1fJM)/r lf1gli6tJon. 

PIOllidfld by Corp~! d ~ - PattJflfld Difltrict