Ground-Water Research of the 

B U.S. Geological Survey

GEOLOGICAL SURVEY 

CIRCULAR 492
Ground-Water Research of the 

U.S. Geological Survey

By C. L. McGuinness

GEOLOGICAL SURVEY CIRCULAR 492

Washington 1964
United States Department of the Interior

STEWART L. UDALL, SECRETARY

Geological Survey

THOMAS B. NOLAN, DIRECTOR

Free on application to the U.S. Geological Survey, Washington, D. C. 20242
Ground-Water Research of the U.S. Geological Survey

By C. L. McGuinness

Adapted from statement presented at April 7, 1964, meeting 

of Subcommittee on Hydrology, Inter-Agency Committee on 

Water Resources, Washington, D. C.

I have been asked to describe to this group 

the ground-water research program of the 

Geological Survey. The first question that 

might be asked is one of the toughest of all 

what is ground-water research? There hasn't 

been a time, at least since O. E. Meinzer 

came along half a century ago, that groundwater workers have been permitted to forget 

that ground water and surface water are interrelated and interdependent, so that there 

is difficulty, at least in some subject areas, 

of deciding whether a given project is groundwater research or surface-water research. 

At the same time, we didn't appreciate these 

relationships quite as thoroughly as we do 

now, problems of ground-water surfacewater interference were relatively uncommon, and there was so much to learn that 

quite sizable segments of research in ground 

water could be considered not to impinge on 

the surface-water field, and vice versa.

But now, all of us in the water game are 

being forced to accommodate ourselves to the 

realization that water, the earth, the skies, 

the oceans, and the living things on and in 

them form one great big complex dynamic 

system and that any action affecting one part 

of the system has more or less widespread 

repercussions in other parts. This is our 

current philosophy in the Geological Survey 

to look at hydrology as the complex field that 

it is and not as the simple subject we would 

like it to be and which we could break down 

into parcels for study in the .most convenient 

way.

It isn't easy for us to decide just which 

parts of the field are appropriate for us to

attack and, of those parts, which ones we ought 

to attack first in meeting our general obligation of explaining the fundamentals of water 

movement, chemistry, and interactions as a 

basis for development and management of 

water. However, I'll do my best to give you 

an idea of the direction of our current research activities involving ground water.

Recognition of water as the principal hydraulically and chemically active part of a 

complex system makes it necessary for us to 

adopt a "systems analysis" approach to our 

part of the solution of water-related problems. We have to set up a model mental, 

mathematical, electrical, hydraulic, or mechanical of the particular hydrologic system 

that concerns us, operate the model to see 

how its functions interrelate, and then change 

the operation in accordance with various proposed actions, such as development of water 

supplies, to see how the model reacts. If our 

model is a good one, we will have an idea of 

how the real system will react and thus be 

able to provide the planners a realistic set of 

alternatives from which to make a choice.

There are all kinds of hydrologic systems, 

but the one with which we will be concerned 

most often is an actual block of the earth's 

crust what we might call a "hydrologic terrane" incorporating a drainage basin or an 

aquifer or a system of aquifers. According 

to the type and complexity of the system, the 

kind of model we choose might be any one of 

those I mentioned, but more often than not it 

will be the electrical analog model. This is 

the one that seems to offer the greatest promise for representation of real hydrologic systems, though we are still a long way from being able to incorporate in the electrical model 

all the flow and chemical factors that will 

have to be considered.
When we come down out of the clouds and 

take a hard look at the problem of modeling 

the ground-water phase of a system, we begin to see our needs for research. The first 

realization we come to is that we have to consider the entire subsurface part of the system 

instead of just the ground-water part; that is, 

we have to look at the zone of aeration as well 

as the zone of saturation, because the zone of 

aeration not only transmits most of the water 

that replenishes the zone of saturation, but 

in other places or at other times it receives 

water from the zone of saturation and transmits it to the atmosphere.

Our needs for knowledge relating to the 

subsurface part of the hydrologic cycle can 

be classified in various ways. One possible 

way involves four categories: (1) The zone 

of aeration and recharge, (2) water .movement 

and storage in the zone of saturation, (3) discharge from the zone of saturation and groundwater surface-water relations, and(4)physical and chemical phenomena.

1. ZONE OF AERATION AND RECHARGE

The zone of aeration, or the unsaturated 

zone, has been almost a no man's land in hydrology, in part because water movement in 

this zone is more complex than in the zone of 

saturation and thus more difficult to study 

and measure, and in part because we are only 

beginning to realize the importance of the 

zone of aeration as a medium for discharge 

from the zone of saturation as well as replenishment to it. Accordingly, difficult as the 

subject is, we are having to give it more attention. We need to know more about the 

mechanism of downward movement by gravity; the relation of capillary conductivity, or 

what you might call effective permeability, at 

various moisture contents; the effects onpermeability of dissolved gases and entrained 

particles in the percolating water; the effects 

of ion exchange and colloidal swelling; the 

mechanism of hysteresis effects involved in 

alternation of downward and upward movement of capillary water; the relative importance of lateral movement in the zone of aeration above a sloping water table such as near 

a stream; the importance of water movement 

in the vapor phase; the mechanism of transpiration as a guide to estimating quantities 

discharged; and so on.

Research on water .movement in the zone 

of aeration is concentrated chiefly at Washington, D. C., under W. O. Smith; at Denver,

Colo., under R. W. Stallman and A. I. Johnson; 

and at Menlo Park, Calif., under Jacob Rubin. 

Smith, Johnson, and Rubin are making laboratory studies of unsaturated flow in columns 

of artificial and natural materials and trying 

to pin down the fundamental parameters controlling movement and retention of water. 

Stallman is studying multiphase flow water 

and air or other gases, and waters of different densities. He is also experimenting with 

transient flow of gas as a means of measuring permeability in the field more rapidly than 

can be done with water.

Rainfall in the very dry southwestern basins 

is so erratic as possibly to rule out our normal water-budget approach to estimating perennial water supplies, and we need to know 

more about what actually does happen. A staff 

at Phoenix, Ariz., under H. E. Skibitzke is experimenting with radar techniques for locating 

areas of storm rainfall as a guide to estimating quantities of water available for surface 

runoff and ground-water recharge and for 

pinpointing areas of potential runoff so that 

stream gagers can get to the areas while the 

arroyos are flowing. Another project is to 

estimate amounts of infiltration, and for this 

purpose Skibitzke is experimenting with infrared-sensing equipment that can be flown 

over areas of recent rainfall to estimate 

amounts of infiltration from the cooling effect 

on the soil. Infrared is useful also in locating 

points of ground-water discharge into streams, 

lakes, or the ocean, and for tracing currents 

in surface-water bodies. It is an aid also in 

geologic mapping.

. There is considerable research on or relating to evaporation and transpiration, in- 

, eluding a series of projects in the Gila River 

valley in Arizona under R. C. Culler; a study 

of the hydrology of the "prairie potholes" of 

the Dakotas and western Minnesota under 

W. S. Eisenlohr; and several studies of waterplant relationships and the effects of vegetal 

.modifications which of course touch on infiltration to and discharge from the zone of 

aeration, under C. R. Daum at Denver, R. M. 

Myrick on the Fort Apache Indian Reservation, 

Ariz., R. L. Phipps at Columbus, Ohio, and 

R. S. Sigafoos here in Washington. T. W. 

Robinson at Menlo Park is continuing his 

general studies of the evapotranspiration process. R. W. Stallman at Denver is working on 

ways to estimate evapotranspiration from data 

on humidity and wind movement at elevations 

between those reachable by instrumented
towers and those which can safely be flown 

by manned aircraft. Radio-controlled model 

aircraft carrying humidity sensors are being 

used in this work.

2. WATER MOVEMENT AND STORAGE IN THE ZONE OF 

SATURATION

The zone of saturation is of special interest 

because it is a widespread economical water 

source whose importance is greater than 

might be assumed from the fact that it yields 

only about a fifth of the total water withdrawn 

for various uses, and also because it is a potentially important medium for storage of 

surplus floodwater as surface reservoir sites 

become scarce and existing reservoirs are 

filled with sediment. Even under natural conditions it is a far greater storage medium 

than all natural and artificial fresh surfacewater bodies put together, and it is most important to be able to estimate quantities of 

water moving through and stored in the zone 

of saturation and the potential availability of 

water from and storability of water in the 

zone.

Therefore the zone of saturation is a 

quantitatively vital part of every analog model of a real hydrologic system. Our efforts 

are aimed chiefly at three major parts of the 

target of making adequate models of the zone 

of saturation: (1) Permeability distribution 

as it affects entrance of water into, movement of water through, and discharge of water 

from the zone of saturation; (2) movement of 

water through fine-grained materials, which 

make up the greater part of most aquifer 

systems and so surround and intertongue with 

the permeable materials as to be the real 

controls on water movement; and (3) the true 

nature and practical measurement of the coefficient of storage, which is equal in importance to the permeability distribution in relation to aquifers as sources of water and 

storage .media.

1. A substantial group of projects are underway in relation to permeability distribution in rocks. R. R. Bennett and J. D. Bredehoeft here in Washington are working on 

textural characteristics of sands and sandstone as a guide to depositional patterns and, 

thus, distribution of permeable channel deposits. P. M. Brown at Raleigh, N. C., is 

heading a project aimed at an understanding 

of depositional patterns and resulting distribution of permeable sediments in the entire 

Atlantic Coastal Plain. Norman Payne at

Baton Rouge, La., is making a similar study 

of the Sparta Sand, one of the principal aquifer 

systems of the Gulf Coastal Plain. J. G. Ferris 

at Tucson, Ariz., is .making a general study 

of the geometry of porous media.

Akio Ogata in Honolulu is studying the fundamental physics and .mathematics of saturated 

flow to develop new equations that can be used 

in interpreting permeability data. H. E., Skibitzke at Phoenix and A. I. Johnson at Denver 

are making studies of flow in artificial and 

natural sands in columns and tanks. Skibitzke 

is continuing to contribute to the design of 

analog models of ground-water flow systems 

by the unit that has been set up at Phoenix. 

W. S. Keys at Denver is studying all aspects 

of borehole geophysics in an effort to devise 

well-surveying techniques that will get more 

permeability and other information per dollar 

spent on test drilling and surveys of production wells. Three "terrane studies" are underway to develop more knowledge of the 

movement of water in certain important nongranular rocks R. C. Newcomb at Portland, 

Oreg., on basalt; F. A. Swenson at Denver on 

limestone and other "carbonate" rocks; and 

F. W. Trainer here in Washington on fractured crystalline rocks.

2. H. W. Olsen, B. B, Hanshaw, and W. O. 

Smith, all here in the Washington area, are 

concentrating on water movement in finegrained .materials, especially to ascertain 

whether Darcy's law of flow in proportion to 

hydraulic gradient holds for material of increasingly low permeability, in which electrical and membrane properties become increasingly important.

3. The principal current effort related to 

the coefficient of storage is that at Menlo 

Park and Sacramento under the direction of 

J. F. Poland and is aimed at separation of 

elastic and plastic deformation in aquifers 

and associated strata that are subjected to 

new stresses, such as those resulting from 

lowering of head. The project was started 

mainly to learn the parameters controlling 

land subsidence in the San Joaquin Valley, but 

it has important implications in better understanding of the coefficient of storage under 

both artesian and water-table conditions.

Research is undertaken as apart of numerous cooperative ground-water investigations, 

as well as in the federally supported research 

program. During the last year advances have
been made in such things as evaluating the 

relation of horizontal and vertical permeability by finite-difference equations, analyzing 

the recession curve of the water table in shallow sediments in dry weather in terms of permeability and storage coefficients, analysis 

of temporary artesian conditions created by 

freezing of soil moisture, and analysis of 

earthquake-induced fluctuations in water level 

in terms of local hydraulic properties of the 

aquifers.

3. DISCHARGE FROM THE ZONE OF SATURATION AND 

GROUND-WATER SURFACE-WATER RELATIONS

We are not yet doing much on upward movement from the zone of saturation into the zone 

of aeration, beyond what is involved in the 

studies of the zone of aeration. The other 

principal type of discharge that into surfacewater bodies is receiving considerable attention, in what might be called studies of 

ground-water surface-water relations.

Such discharge is of enormous economic 

importance because, in drainage basins lacking large artificial reservoirs or natural lakes 

and swamps, ground water is the source of 

the low, or base, flow of streams. It is important to study the geologic and climatic controls of water movement from aquifers into 

streams and the effect of rises in stream 

stage in stopping or even reversing this flow 

and thus contributing to ground-water storage.

H. H. Cooper, formerly at Tallahassee, Fla., 

and now here in Washington, and his associates have made important contributions to the 

discharge of coastal ground water as affected 

by tides. He is now working on the mathematics of "bank storage" along streams. M.I. 

Rorabaugh at Tacoma, Wash., who made important contributions to the theory of induced 

infiltration from streams in his work at 

Louisville, Ky., is working on the estimation 

and prediction of base flow as a guide to 

stream management, in cooperation with the 

Bonneville Power Administration. R. F. Hadley at Denver is studying infiltration losses 

from ephemeral streams the principal 

source of ground-water replenishment in 

Western alluvial basins. D. R. Dawdy atMenlo 

Park is attempting to develop an overall analytical .model of the hydrologic cycle, of 

which one important element would be base 

flow of streams. E. C. Pogge, G. R. Kunkle, 

and their associates at Iowa City are studying 

streamflow in relation to aquifer characteristics, including especially bank storage during floods and origin of base flow.

4. PHYSICAL AND CHEMICAL PHENOMENA

The description of the program so far has 

stressed the movement and storage of subsurface water and left for the last the studies 

involving the chemical properties of water 

and such physical characteristics as temperature. Actually, these factors cannot be separated from the flow problems because they 

are closely interrelated. For example, as I 

mentioned, electrochemical and membrane 

effects are importantly involved in the .movement of water through fine-grained materials. 

Temperature also is important because of its 

effect on viscosity, the effect being rather 

direct in subsurface flow whereas it is a 

relatively minor factor in turbulent flow in 

streams, and it will become still more important as surplus surface water is deliberately injected into aquifers and then recovered.

Obviously, studies of fundamental chemistry 

relate to the whole hydrologic cycle, not just 

ground water or surface water.

The project classification used in our description of the hydrologic research program 

for fiscal 1963 follows the hydrologic cycle. 

Studies relating to the chemical or physical 

properties of water are found in each of the 

sections, and there are some dozens of individual projects, including those described 

briefly below.

G. L. Stewart and his colleagues here in. 

Washington are studying the use of various 

radioactive and stable isotopes for tracing 

water flow both on the surface and underground and for identifying sources and dating 

periods of replenishment. The project is 

concentrating on tritium at present. W. D. 

Haney is carrying on a related program to 

develop methods for age dating of water.

D. E. White of the Geologic Division and 

Robert Schoen of the Water Resources Division at Menlo Park are studyingthe chemistry 

of deep thermal waters and their relation to 

the enclosing rocks. These waters play a 

relatively minor part in the hydrologic cycle, 

but the information gained on water-mineral 

relationships can be applied to the fresh-water 

part of the cycle.
A. W. Gambell, Jr., here in Washington, 

D.C., is heading a project to study the chemistry of precipitation as it reaches the ground, 

as a determinant of the quality of surface and 

ground water. The project is try ing to identify 

the source of certain constituents and the general pattern of transport by air. It appears 

that the quality of water in some areas, such 

as parts of the Atlantic Coastal Plain, is determined more by constituents contributed in 

precipitation than by those from terrestrial 

sources. In a related project, Gambell and 

W. H. Durfcm are studying sediment particles 

carried in suspension and the state of chemical equilibrium between them and water when 

they are washed out of the air.

The hydraulic-model studies of H. E. Skibitzke and others at Phoenix include one of 

coastal discharge of fresh ground water and 

of dispersion and diffusion of salt from the 

adjacent sea water into the coastward-flowing 

fresh water. Studies by H. H. Cooper and 

others have shown how tidal fluctuations and 

the accompanying advance and retreat of the 

salt-water front provide energy for the movement of salt from the sea to the zone of diffusion and back to the sea. These relationships are fundamental to an attack on problems of saline encroachment in both coastal 

and inland areas.

Temperature is a basic control of evaporation and transpiration and is involved in all 

the studies mentioned previously on this subject.

R. S. Aro at Denver is heading a project to 

determine the ecologic criteria that will be 

involved in proposed conversion of semiarid 

piny on-juniper areas to grass to increase 

water yield. The criteria studied include soil 

pH and chemistry as related to vegetal type 

under both natural and changed conditions.

F. A. Branson at Denver and his staff are 

studying the distribution of plant species along 

the 103d .meridian from southeastern New 

Mexico to Nebraska in relation to air temperature, and also the response of soil .moisture 

and some other soil characteristics to the 

same thermal gradient. In related projects 

R. F. Miller and his staff are studying the 

chemistry of soils in relation to amount and 

seasonal movement of soil moisture in areas 

of both dry-land and phreatophytic vegetation.

M. F. Meier and associates at Tacoma, 

Wash., are studying the hydrology of glaciers, 

especially their response to climatic fluctuations, as a guide to long-term prediction of 

water availability from mountainous areas.

R. C. Newcomb's basalt-hydrology project 

centered at Portland, Or eg., is now getting 

into the geochemical phase in an attempt to 

derive useful generalizations about the chemistry of the water in relation to rock type and 

to movement of the water. Similarly, F. A. 

Swenson's lime stone-hydrology project is 

studying the sources of carbonic and other 

acids which cause solution to take place hundreds or even thousands of feet below the 

water table. V. T. Stringfield is making a 

similar study of the artesian limestone of the 

Southeastern States.

J. H. Fethat MenloParkis assembling maps 

showing the location, depth, and salt content 

of saline water in the conterminous United 

States, as a contribution to the saline-water 

conversion program of the Department of the 

Interior.

P. R. Stevens at Austin, Tex., is heading a 

project to study the occurrence of brine in 

selected areas of the Permian basin. The objective is to determine the mode of occurrence 

of the brine and its dynamics, so that projects 

for controlling its discharge maybe designed 

realistically. Some brine-control projects 

have been based on the assumption that brines 

are generated by solution of salt from the 

strata by locally infiltrating precipitation and 

that damming spring outlets and creating 

back pressure will reduce the discharge of 

brine. At least one or two such attempts 

have failed. The brine may be a regional 

body which discharges at the most convenient 

points but which, if those points are dammed 

up, will simply discharge elsewhere. The research project is designed to get the answer 

to this fundamental question, which is an important one because of the quantity of other - 

wise usable water that is spoiled by the brine.

D. W. Hubbell and his associates at Ft. Coigns, Colo., are studying sorption of radioactive wastes on particles of stream sediments and the dispersion, transport, and deposition of the contaminated sediments.

R.G.Godfrey and associates here in Washington are studying flow and salinity relations
in estuaries as affected by tides. The project 

is related more to flow than chemistry but 

obviously has important implications in relation to the quality of water available from 

estuaries and adjacent aquifers and the conditions affecting deposition of sediments and 

contaminants.

W. O. Smith here in Washington is studying 

the freezing point of moisture in clays in re - 

lation to mineral type and exchange-ion content. The objective is to provide information 

applicable to the study of ground-water availability in permafrost areas.

Smith is also studying the dielectric properties of moist soils and rocks to determine 

their relation to moisture content. The goal 

is to develop another technique of soil-moisture measurement that doesn't involve disturbance of the moisture itself.

The studies under H. W. Olsen and B. B. 

Hanshaw mentioned previously are aimed 

largely at liquid movement in clays, including 

the role of hydraulic, thermal, chemical, and 

electrical gradients. Hanshaw's work is 

aimed especially at the "membrane" properties of shale, which have what could be called 

a physicochemical basis and which may be 

important to understanding certain anomalous potential distributions observed in <" ;ep 

basins.

R. C. Scott and K. W. Edwards at Denver 

are heading studies of the distribution of radioelements in natural water. The general 

objective is to provide basic information to 

assist studies of the relation of these elements to health, to mineral exploration, and 

to the movement and chemistry of water 

throughout the hydrologic cycle.

B. F. Jones and his staff at Washington are 

studying the composition, especially as to 

minor elements in water, in closed lake basins 

of the West, where, in spite of some losses to 

and gains from outside the basins, the geochemical processes and budgets are largely 

contained within the basins and are especially 

amenable to quantitative study.

Ivan Barnes at Menlo Park is heading a 

project aimed at elucidating some of the fundamental reactions in ground water. One of 

the most important applications is in problems of acid mine wastes. One product to 

date is a geochemical model, supported by

field tests, which demonstrates that water 

and sulfidesdo react in the absence of oxygen. 

Thus air is not the only source of mine acid, 

and sealing mines is not necessarily a satisfactory way to ameliorate these problems. It 

is proposed to study gases generated in deep 

waters to provide further information on the 

exact reactions involved under anaerobic 

conditions.

W. L. Poizer at Menlo Park is studying the 

solubility of kaolinite as a step in under standing the solution of silica and aluminum and 

equilibrium with the solid phase.

E. A. Jenne and his staff at Denver are 

making a broad study of ion-exchange phenomena and the chemical reactions of radioactive substances, largely with the objective 

of evaluating the decontaminating effect of 

earth materials on waste waters disposed of 

underground.

In collaboration with the Atomic Energy 

Commission, W. A. Beetem and his staff at 

Denver are studying the movement of radionuclides through earth materials and also the 

solubility of materials formed by underground 

nuclear explosions in relation to contamination of adjacent ground water. In one part of 

the program a study is being made of the 

solubility of radioactive materials from particles of various sizes washed down by rain.

V. C. Kennedy and staiflfat Denver are studying the mineralogy of stream sediments in 

relation to particle size and ion-exchange 

capacity, in an attempt to understand the 

chemical balance between water and sediment 

in the streams.

J. D. Hem and his staff at Menlo Park are 

continuing their studies of the fundamental 

chemistry of certain hydrosolic metals. Work 

on iron has been largely completed and pub - 

lished. Work on manganese is well underway; 

that on alluminum is in an early stage.

M. W. Skougstad and his staff at Denver are 

working on improvements of analytical methods, especially of minor elements for which 

available methods are not satisfactory.

K. V. Slack here in Washington is heading 

studies of the relation of stream biology to 

water chemistry. Phases include the chemical controls on generation of stream biota 

and, in turn, the effect of the biota on water
quality; the chemistry of a calcite-precipitating stream in California in which the controls are still all natural; and the effect of 

leaf mulch on water composition.

William Back here in Washington is studying the equilibrium of carbonate compounds 

as a guide to source and movement of ground 

water, especially in the Atlantic Coastal Plain. 

He has recently visited Israel to help with 

the geochemical aspects of that country's ambitious water-development plan.

Studies under A. O. Waananen at Menlo Park 

on the hydrologic effects of urbanization will, 

of course, devote attention to the water-quality 

effects. Work is now underway in the San 

Francisquito Creek watershed.

The chemistry of organic compounds in 

water is of increasing importance in relation 

to water contamination. W. L. Lamar at Menlo 

Park, Eugene Brown at Sacramento, C. H. 

Wayman at Denver, and their staffs are studying the identification, separation, and estimation of various organic substances. Wayman's 

work on detergents is well known. The Survey now has a very modest program of research on pesticides and herbicides, which of 

course are among the principal actual and 

potential contaminants of water. About 14 

areas have been selected for study. One of 

these is the Loxahatchee Refuge in Florida, 

where 2, 4-D has been used to control water 

hyacinth. Wayman is also supervising a study 

of the sulfur-water system under both aerobic 

and anaerobic conditions, which has potentially important applications in the study of 

both organic and inorganic contaminants.

Frank Clarke is studying problems of the 

corrosion of well casings and other underground metallic structures. The vast New 

Valley program in the Western Desert of 

Egypt, one of the principal hopes for economic growth there, is imperiled by severe 

corrosion of wells. Similar problems exist 

in Pakistan, where Clarke is at the moment.

The Survey, along with other agencies, is 

participating in the international programof research on stream waters under the Organization for Economic Cooperation and De - 

velopment. The problems cover the same

range as similar problems in this country. 

H. A. Swenson and M. W. Skougstad are the 

Survey's representatives in the United States 

delegation.

One important support activity related to 

water quality is the project under G. A. Billingsley at Raleigh, N. C., to develop automation and processing techniques for waterquality data.

CONCLUSION

Obviously, what I have described is an extremely wide-ranging and diversified program. Even so, it covers only a small part 

of what still remains to be done both inside 

and outside the Survey before the Nation will 

have a sound basis for water management and 

quality control. We in the Survey feel that we 

have a good general understanding of the hydrologic cycle, and we are making progress 

in orienting our research toward aspects of 

the cycle where our ignorance is greatest and 

where at the same time the need for information to handle current national water problems 

is most intense. However, we can't do and 

have no intention of trying to do the whole job 

ourselves. We acknowledge with pleasure 

that scientists and engineers in other agencies, in universities, and among consultants 

are doing excellent work in all parts of the 

hydrologic cycle, including parts such as 

ground water where we are more or less 

widely recognized as leaders. Our pleasure 

is especially great where these men are Survey graduates, as some of them are.

One of our most difficult and yet most necessary jobs is to keep in touch with related 

research all over the country and the world, 

so as to take advantage of new developments 

and avoid duplication and lost motion. Your 

group has a related problem to help the 

Federal Government decide what ought to be 

undertaken in the way of hydrologic research 

and water-management projects. The job is 

a tough one because of the innumerable crossconnections throughout both the hydrologic 

cycle and the spheres of interest of Federal 

and other agencies and institutions interested 

in water. I wish you good luck in your delibearations.

U. S. GOVERNMENT PRINTING OFFICE : 1964 O - 743-840