ALBERT

Notes: A two-dimensional, passive element electric analog model was used to determine the spatial distribution of natural ground-water recharge in the Santa Cruz River basin of southern Arizona. Existing records were used to draw a ground-water level contour map of the area in its undeveloped condition. The model was made to duplicate these contours by varying inputs from known locations of recharge. Recharge distribution as determined by the model was consistent with previous estimates, but no direct correlation was found with the contributing drainage area.

Notes: The tidal efficiencies of wells tapping the principal artesian aquifer in Glynn County, Georgia decrease with distance from the influencing tidal body and also decrease with well depth. Although the magnitude of water-level fluctuation of these wells is largely dependent upon the distance to a large tidal body, the time of a high or a low water level in the wells is mainly dependent upon the time of a high or a low tide in a small, nearby tidal body. A modified formula for computing tidal efficiency is developed:〈displayedItem type="mathematics" xml:id="mu1" numbered="no"〉〈mediaResource alt="image" href="urn:x-wiley:0017467X:GWAT24:GWAT_24_mu1"/〉 From this formula, tidal efficiency can be calculated rapidly and easily

Notes: The frequency distribution of dissolved-solids content of ground waters in geologically and climatologically homogeneous terrane units commonly approximates a log-normal distribution. A graphic logarithmic transformation is de-scribed which permits rapid calculation of approximate values for the mean, standard deviation, and coefficient of variation. Statistical parameters calculated by this method show good agreement with known physical conditions in the terranes studied and are precise enough for use as a mea-sure of variability of quality of ground waters for national planning purposes.

Notes: Photogeologic study has been useful in the location of ground-water sources in the state of Sao Paulo, Brazil, and could be important to the investigation of water resources in other areas.Until 1963, it was believed that large areas of the state were unsuited for the location of ground-water wells (as in pre-Devonian crystalline formations) and others weregenerally considered too hazardous (Paleozoic and Tertiary: sandstone lenses in shales). Since that time, when aerial photographs of the whole state became available, the authorhas verified an earlier hypothesis of his own that there are actually very few areas in the state which do not have suitable locations for water wells, and that photogeology is a most valuable method of prospecting.The water sources are parts of highly developed fault/ fracture systems which are identifiable on aerial photo-graphs, at least in this warm humid climate with dry season. Over the fractures the rocks are deeply decomposed, the debris are removed in the rainy season, and existence of water in the dry season promotes higher and denser vegeta-tion along aquiferous fractures, which usually are located in deep straight-line valleys. Even where competent beds are overlain by more than 100 m of unconsolidated strata, many discontinuous nets of parallel straight-line segments are detectable probably because all fractures are really faults with significant throw.To be most effective, the method requires stereoscopic study of areas having dimensions on the order of 10 × 10 km. The selection of locations for drilling should be sup-ported by analyses of the dip of fracture planes (hade) and by other geological-geophysical methods, especially by subsoil electrical resistivity surveying.

Notes: The purpose of this paper is to stimulate additional interest in the hydrogeologic aspects of the International Hydrological Decade (IHD) program and to urge the full cooperation and participation of hydrogeologists in the research and educational activities of the Decade. The IHD, 1965–74, will strengthen the scientific base for water use and conservation, stimulate education and training in hydrology, and improve the ability of developing and developed countries alike to cope with their water resources problems. UNESCO provides an international intergovernmental umbrella and the Secretariat for IHD. More than 90 Member States of UNESCO are participating in IHD and a majority of these have established National Committees for IHD.The UNESCO/IHD program will consist primarily of activities of participating countries themselves, catalyzed, coordinated, and supplemented by international intergovern-mental agencies and scientific associations. Activities of Member States of UNESCO include: collection of basic data through data analysis and applied hydrology; applied and basic research; continental and global water balances and the global hydrological cycle; establishment of hydrological networks and the development of technical competence; fundamental research; definition of principal hydrological features of countries such as precipitation, discharge of water, sediment and dissolved load, evapotranspiration, distribution of tritium in precipitation, surface and ground waters; experimental basin studies to provide insight on the interplay of environmental and hydrological parameters in a broad range of geological, climatic, and ecological conditions; distribution of water in the atmosphere, in lakes and rivers, underground, in permanent ice and snow and permafrost; studies of the rate at which water moves through the hydrologic cycle; use of orbiting satellites and remote sensing instruments for measuring phenomena in the atmosphere and at the Earth's surface and for relaying observational data; organization of egional advanced training and study courses and hydrological institutes; exchange of teams of experts, exchange of professors and research scientists; and organization of symposia and regional seminars.The US/IHD program focuses on the following five major objectives: (1) large-scale balances of water and water-borne material studies; (2) hydrological performance of river, lake, and ground-water basin systems studies; (3) studies of specific hydrological processes and their variations in time, and improvement of methods and techniques; (4) education and training; and (5) services providing coordination and administration support. These objectives provide a framework within which the scientific and engineering community can contribute to IHD. A provisional US/IHD program statement identified, among others, the following hydrogeologic activities: estimation of ground-water discharge to the sea, effects of variations in piezometric head on land subsidence, hydrology in limestone areas, radionuclide tracer studies, chemical behavior of ground water, and dispersion in moving ground water.Hydrogeologists are urged to submit proposals concerning activities for possible inclusion in the US/IHD program. The following seven criteria guide the formulation and inclusion of activities in the US/IHD program by the U. S. National Committee for IHD: (1) the activity is sufficiently fundamental or aimed at results so useful that it will interest all hydrologists; (2) the activity requires joint or coordinated work in two or more countries; (3) the activity concerns a problem whose solution and verification would be improved by work in two or more countries; (4) the activity concerns continental, hemispheric, or global phenomena or processes; (5) the activity requires action in international areas such as polar regions, international waters, and multi-national basins; (6) the activity involves the hydrologic use of earth-orbiting satellites; and (7) the activity involves intercountry exchange or visits of personnel (in some instances, the exchange or visit itself may be the main item of interest). Proposals may be of projects already in progress, for expansion or modification of on-going projects, or for new work. Proposals may be submitted as contributions, requiring no financial aid from or through the IHD; for endorsement by IHD as an aid in obtaining financial aid elsewhere; or, when funds become available, as IHD projects receiving financial assistance from the IHD. Further information may be obtained from: U. S. Na-tional Committee for the International Hydrological Decade, National Academy of Sciences, 2101 Constitution Avenue, N. W., Washington, D. C. 20418.

Notes: A type-curve method for determining anisotropy of unconfined aquifers, developed from electric analog simulation, is applied to drawdowns observed near, a well pumping from a glacial outwash aquifer at Piketon, Ohio. The coefficient of vertical permeability, P z'averaged 365 gpd per square foot. Computed drawdown for the pumped well, based on this value, differed by only a small amount from the observed drawdown. The coefficient of storage, determined from type curves for an image well system, averaged 0.20, typical of unconfined aquifers. Application of the method required a thorough knowledge of geohydrologic controls operating at the test site.

Notes: Criteria and factors are considered which affect the design of a Hele-Shaw viscous flow model for use in ground- water studies. Procedures and construction techniques for assembling such a model are outlined. Some of the advantages and drawbacks in using a viscous flow model are discussed, Three examples are used to demonstrate the use of the model

Notes: A nuclear (atomic) explosive, detonated at suitable depth below the land surface, appears to offer substantial advantages and economies as a tool in the development and management of water, under certain special hydrologic situations. It is appropriate, therefore, that we seek to understand not only the potentials, but also the limitations of such a detonation. This paper is a first, small step toward that end.Greatly over-simplified, what does an underground nuclear detonation do that it can become a tool of water development and management? Consider first a detonation at a depth sufficiently great that none of the products vent to the atmosphere. Minimum depth for such “containment,” in feet, is close to: 〈displayedItem type="mathematics" xml:id="m1"〉1〈mediaResource alt="image" href="urn:x-wiley:0017467X:GWAT13:GWAT_13_m1"/〉in which W = explosive energy, in kilotons.

Notes: In this short paper, selected water quality problems and the research efforts aimed at their solution supported under P. L. 88–379 (the Water Resources Research Act of 1964) at State Water Research Centers are presented. The water quality problems and associated research efforts presented are not necessarily of high priority with respect to the national needs for water quality knowledge; rather, the problems and research discussed are presented as typical of local or regional situations and as examples of the awareness of State Water Resources Research Centers to the local or regional needs for improving water quality management.Selected water quality problems associated with urban- ization, modern agriculture, industry, recreation, and natural environments are discussed with respect to the needs for new knowledge leading to improved management of water resources. Selected Water Resources Research Centers' projects with the objectives of discovering some of that new knowledge are discussed with respect to the research approach adopted by the investigators.

Notes: Maximum yields from minimum aquifers can be accomplished only by strict adherence to best known practice procedures while following the three necessary steps to well completion. These steps are well design, well construction and well development.In well design good practice begins with an accurate log and the obtaining and careful testing of formation samples. From such data, optimum depth, diameters, screen settings, and gravel pack gradations for expected yields can be selected.Well construction should incorporate equipment suited for the kind of formation, size of well, and depth to be drilled. It should be operated by competent and reliable personnel capable of faithfully maintaining all specifications and finishing in a reasonable time, with a well in which all measurements shown on the log are correct.Development techniques which are appropriate for the well, aquifer, and drilling equipment should be used, al-though it appears the high velocity horizontal jetting tool, used in conjunction with chemicals and regulated pumping, offers the most promise.

Notes: The nature and extent of movement of ABS (alkylben-zenesulfonate) and other sewage components through natural soils were studied in the laboratory and in the field north of Denver, Colorado. Small amounts of ABS and bacteria pass through soils and reach the zone of saturation, where they move laterally down-gradient several thousand feet. Total dissolved solids show little fluctuation during such movement, possibly because extracted solutes are replaced by other solutes leached from the soils during water infiltration.In laboratory studies Denver sewage-plant effluent was filtered through packed columns of 8 types of soils. ABS was not significantly removed by most of the soils; how-ever, muck, greensand marl, and residual basalt soil ini-tially removed up to 94 percent of the ABS. Some ABS was removed only after development of bacterial slime on the soils; subsequent infiltration caused leaching of the slime and its adsorbed ABS and other constituents. All soils initially removed about 90 percent of the bacteria within a few feet of travel, but a small percentage passed through the soil. Bacterial clogging occurred quickly in the fine soils but only in modest amounts in the coarse sand, even after three months of flow.Field studies included analyses of river and irrigation water contaminated from a sewage-plant effluent, and well water from selected sites down-gradient between unlined irrigation ditches and the river. Concentrations of ABS and bacteria were significantly reduced during infiltration of irrigation ditch water to the water table. As noted in the laboratory the concentrations of both of these contaminants can be reduced through soil filtering action. In addition there may be some dilution of the infiltrate by the ground water. Dissolved solids showed practically no change between the ditches and the wells.

Notes: The consultant expects the driller to provide good data and competent performance. Exchanges of views associated with drilling and construction can prove to be mutually beneficial. Contacts between the consultants and the drillers have a tendency to upgrade the quality of the basic datacollected. These contacts may aid the driller in delivering full performance and thus improve the overall quality of thedrilling and construction he performs for the client. As a result, everybody associated with the water well industry-drillers, consultants, and clients - stands to gain by these contacts. It is hoped that these beneficial contacts within the water well industry will become even more common in years to come so we all can gain from one another's knowledge and experience.

Notes: A graduate program in hydrogeology is described, in which the field is defined as encompassing the whole range of processes operating in water and water-mineral mixtures at and near the earth's surface. The interdisciplinary character of this training is insured by requiring both a minor from another department and course work in other sub-disciplines of hydrogeology in addition to the one in which the thesis is carried out. The importance of nonscientific aspects of hydrogeology is recognized by allowing for minors in fields such as economics and business administration.

Notes: The Colorado Assembly passed three laws in 1965 concerning water rights. Two of the new laws pertain directly to ground water and take cognizance of the fact that some wells divert water that would otherwise reach a stream. The use of ground water is now regulated under the doctrine of prior appropriation, which has applied to the administration of surface water in Colorado since 1852. Under the doctrine of prior appropriation, the first person to make beneficial use of water establishes a right to use that water even when there is a shortage of water for later appropriators.This paper discusses the new laws as they relate to hydrologists and others concerned with hydrology. The law sets up administrative processes for implementing the use of water but raises many questions. Proper hydrologic investigations are necessary as a technical base for administration of the laws.

Notes: Measurements of ground-water recharge in sand drift aquifers in northern lower Michigan show that winter and spring precipitation provides a major portion of the annual water yield. In general, the accumulation of snow beneath forest canopies varied inversely with crown density during the winters of 1962 and 1963. Pine plantations with crown densities of over 80 percent in winter had 1.8 inches less water in the snowpack than neighboring deciduous forests, at the time of maximum accumulation. Ground-water recharge during the melt period was proportionally lower beneath the pine forests where snow accumulation was least. The difference in snowmelt recharge was a major factor in the smaller annual water yields measured under these pine forests.

Notes: It is the purpose of this paper to call ro your attention the existence of the International Hydrogeologic Map Display and the International Legend for Hydrogeologic Maps, and to encourage those in the USA working in the water resources and associated fields to review these recommendations and forward their comments so that they may in turn be relayed to the next meeting of this international commit-tee. It is requested that any maps following the legend be forwarded for addition to the committee's file and use in the Internationa] Display at the next General Assembly meeting of IUGG.

Notes: The Republic of Korea shares the world-wide problems of water supply variability in time and space - they have too little water at some time and in some places, and too much water in others. Drouth is a recurring threat; floods occur nearly every summer. The floods of July 1965 are reported to have been the most costly in history. The population is increasing at a rapid rate and material things are in short supply. However, the people of Korea are making a tremendous effort to modernize facilities, construct an industrial base, improve agricultural practices, control the rivers and develop water supplies, and in general, improve the standard of living. With a per capita income of about $80 per year, Korea has a long way to go in its climb up the economic ladder, but the people are able, intelligent, energetic and avid for learning and progress. They enjoy one of the highest literacy rates in the Far East, and have a trained core of professionals in most fields, except they lack a trained cadre of specialists in ground-water studies and have very few experienced water well drillers. During the Japanese occupation of Korea systematic ground-water studies were begun, and ground-water development followed soon afterwards. But the limited staff of Japanese geologists employed in the effort returned to Japan at the end of World War II in 1945. In the uncertainty of the next 8 years, which included the Korean War, it was impossible to develop trained manpower and an organization.Presently, there is widespread interest on the part of the Korean Government to develop ground water wherever it may be for such uses as irrigation, industrial supply and development, municipalities, villages, and sanitary rural supply. As a result of this interest the author spent four months in Korea in the fall of 1964 and the spring of 1965 at the request of the Agency for International Development, U. S. Department of State, to review the situation and report on the feasibility of a United States supported effort to help the Korean Government to make systematic studies that would lead to ground-water development, and to any necessary improvement of their methods of hydrologic data acquisition and utilization.

Notes: The digital computer is used on a routine basis in the ground-water program in Kansas for tasks ranging from the listing of water-quality data in tabular and publishable form to statistically and graphically analyzing a mass of data.In the past year a number of computer programs in FORTRAN IV have been developed by Charles O. Morgan and Jesse M. McNellis using an IBM-7040 computer to store, retrieve, and manipulate water-quality data. These programs:(1) Tabulate data at the rate of 40 chemical analyses of water per minute in a format similar to that found in the Kansas ground-water publications.(2) Perform necessary calculations and print Stiff diagrams at the rate of 30 per minute.(3) Perform necessary calculations and print Piper diagrams, including a square modification of the normally diamond-shaped cation-anion diagram, and trilinear diagrams of the cations and anions. The symbol representing the analyses located on the diagrams can be designated by either an analysis number or a geologic unit number. A cation-anion diagram showing the average chemical composition of water for an aquifer can also be printed. These diagrams for 50 analyses can be produced in 1.5 minutes.(4) Plot maps of 42 individual, combined, or calculated parameters obtained from the data cards. These maps can be plotted to any specified scale and for as many as 10 designated geologic units. Computer time involved for one map with 50 plotted points is 15 seconds.It is estimated that the use of these programs will save several man-months during a ground-water study, and the error inherent in the manual manipulation of data is greatly reduced. The present cost for running 50 analyses through the four water-quality programs on the computer is approximately $20.

Notes: In the past 20 years, since 1945, there has been a substantial increase in the application of electric well logging to water wells. In the early days, there were very few water wells being logged, principally city supply wells and other larger commercial wells. Now, it is not uncommon to be called to service water wells of all sizes, even the small back yard well. The well drilling industry is becoming more and more aware of the benefits that can be derived from use of the electric log, and there will almost certainly be an increase along these lines in the years ahead. There are some very good reasons for this growth and acceptance of the electric log, and pointing out some of these reasons and applications of the electric logs to water well drilling is the purpose of this paper.

Notes: This paper is concerned with the development of the application of theoretical aquifer concepts to the administration of water rights from ground-water sources, and exam- ples of the application are given. Kansas operating under the Appropriation Doctrine is applying the rule of priority of right, the first in time is the first in right, to the administra- tion of water rights from ground-water sources. The application is not absolute in that some mutual interference pre-scribed by the reasonable raising and lowering of the water level must be allowed as specified in the law.The application of hydrologic considerations in the administration of problems between individual wells is first given. The scope is then expanded and data presented for the application to large basin development where pumpage is largely from storage, using the current situation in the high plains area of western Kansas for the example.An addition to the normal ground-water basic data collection program called a “Key Well” program is proposed where the key well is a production well. This well is to be fully instrumented to give information on diversion costs and evaluate methods of construction, as well as identify any changes in aquifer characteristics with respect to time.

Notes: Chemical analyses of ground-water samples taken from differing depths in a four-county area in east Texas showed a general stratification with respect to dissolved iron, pH and hardness. On the basis of this stratification the waters of the ground-water reservoir were divided into a shallow zone of oxidation, A; a deep zone of reduction, C; and an intermediate and unstable zone, B, in which waters from above and below are mixed. Ground water from zones A and C generally is almost free of iron, whereas water from zone B generally contains objectionable amounts. This zoning is explained by recent laboratory work and theoretical data on iron in natural waters. Wells constructed to draw only from zones A or C should yield water relatively free of iron.

Notes: During a three-month trial period, 70 million gallons of industrial wastes were successfully injected at moderate pressures into a deep limestone in the westernmost part of Florida. The movement of these wastes is expected to be predominantly southward toward the natural discharge area which is presumed to be far out in the Gulf of Mexico. The limestone lies between two thick beds of clay (aquicludes) and contains 13,000 parts per million salty water. A series of aquifers and aquicludes appear capable of preventing contamination of the overlying fresh-water aquifers.

Notes: The States of Nebraska and Kansas are negotiating a compact for apportionment of the waters of the Big and Little Blue Rivers. So that the negotiating officials could allocate the water equitably, the amount of streamflow depletion caused by ground-water withdrawals upgradient from the State line needed to be determined. At the request of the Nebraska officials, the U. S. Geological Survey constructed an electric analog model which could be used to determine the amount of streamflow depletion expected to occur in the next 60 years.The model simulates hydraulic conditions in an area of 7,400 square miles which includes the entire area drained by the Big and Little Blue Rivers in Nebraska. The trans-missibility of the aquifer (Pleistocene in age) ranges from less than 1,000 to as much as 300,000 gallons per day per foot, and the storage coefficient averages about 0.20. The transmissibility values are based on examination of test- hole samples from more than 400 test holes in and adjacent to the basin.Analysis of the model indicates that predicted maximum ground-water withdrawals between 1962 and 2022 will not deplete the base flow of the Big or Little Blue Rivers by more than 5 percent.

Notes: California has an enormous stake in the Colorado River. In the southern portion of the State, 80 percent of the water used is furnished by the Colorado River, and this area needs still more water in the immediate years ahead. But it cannot get more from the natural supply of the Colorado. The river is already over-committed, and California in fact may have to cut back on its present take from that source. This is not the Colorado River in Texas; Los Angeles has gone hundreds of miles to get water, but has not reached that far east-yet.

Notes: A simplified method for determining the coefficient of transmissibility of an aquifer being pumped intermittently is developed by applying Stirling's Approximation Formula to the factorial functions in the Theis and Brown equation for drawdown in a well due to intermittent or cyclic discharge. A table of values of K, a term used in the simplified method, corresponding to the fraction of each cycle during which time discharge occurs is also presented.

Notes: During February and March 1964, the U. S. Geological Survey ran caliper, conductance, and temperature logs on several wells in the Sarasota area. The Florida Geological Survey had previously run gamma ray and electric logs on the same wells. Two flowing wells were selected for packer testing. The two wells are about the same depth, penetrate essentially the same geologic horizons, and are about 16 miles apart. The packers were set in the wells between the producing horizons of the formations penetrated and each of the horizons was tested for head, amount of production, and quality of water. One of the tests produced excellent results, indicating that the various producing zones were effectively isolated by the packers and that different quality of water, quantity of water, and a different head was available from each zone. The other test did not show sharp differences but did indicate the extent of contamination of the producing horizons in a flowing well which had been capped for approximately two years. These tests indicate that packer testing can measurably add to knowledge of the separation of permeable zones.

Notes: Quicksand is no myth, nor is it a rare phenomenon, either on the surface or in the subsurface. There is probably quicksand in every State of the U.S.A. where enough gradient is available to produce upward moving ground water. Surface quicksand is likely to occur in hilly country, especially in regions of calcareous rocks which often con-tain solution openings and favor the occurrence of springs. It is often present near stream banks and stream beds, either along their shorelines, under water, or occasionally in the bottom of an apparently “dry” river.Subsurface qurcksand rs found in loosely consolidated or uncemented alluvial, fluvio-glacial, or lacustrine sediments, which are usually well sorted and clean. It has been reported to depths as great as several hundred feet, and from a few feet to as much as 200 feet thick.In water wells, a “quick” or “heaving” condition may exist (as much as 150 feet) if a confined, permeable, loose silt, sand or gravel stratum is continuous to distant higher ground, and is subject to a greater head of water existing at the higher elevation, i. e., if artesian conditions exist.Similar material may heave in a water-table (unconfined) well, due to the natural tendency of granular materials to move toward a drill hole when lateral support is removed (the drill cuttings). Heaving results from a loss of shearing strength as pressure is reduced when a drill hole upsets natural equilibrium. Suction produced by suddenly withdrawing bailer or tools further contributes to disturbing natural conditions.Quicksand is commonly sand (usually fine to medium grained) with an effective size ranging from less than 0.001 inch to 0.005 inch. It is often finer than sugar, which has an average effective size of 0.008 inch, to which it is often compared by drillers. Stoke's Law explains why fine, round- ed grains become “quick” much more readily than coarser sand or gravel.If sufficiently permeable, quicksand aquifers can successfully be used for water supplies, providing proper screening devices are available. However, representative driller's samples; sieve analyses; choice of(or omission of) sand filter pack; proper slot selection; low (0.1 fps) en- trance velocity; and careful, patient development techniques are important prerequisites.Permeability of quicksand varies widely, but might range from approximately 50 gpd/ft to 800 gpd/ft, and average between 100 or 175 gpd/ft2. From a 5-feet thick quicksand bed, and at shallow depths, 1 to 10 gpm may be obtained for domestic or farm supplies using screened wells and drive points. Sufficient yields (250 gpm or more) for municipal wells are also possible.Drilling and completion problems with cable-tool wells can usually be overcome by: 1) watching casing alignment; 2) running bailer slowly; 3) keeping a continual high head of water inside casing; 4)using a heavy string of drill tools; 5) allowing controlled sand-heaving; 6) using short casing drives; 7) jetting with high-pressure water to wash-free tools if seized by a sudden heave; 8) avoiding thin-walled casing; 9) drilling with a mixture of bentonite or native clay and water sludge; and 10) casing above the surface if the well is flowing.Rotary drilling and completion problems are minimal, but unless unusual pressures are encountered, quicksand aquifers may be overlooked. Caving can be prevented by providing sufficient hydrostatic differential pressure, and by using a heavy weighted drilling fluid.Well screens can be set by bailing them down through a quicksand “plug” which may have formed, and completing using the standard pull-back method. A self-closing bottom (washdown fitting) can also be used to jet-down a screen while utilizing a high-velocity water flow.In some cases a sand filter-pack surrounding a continuous-slot well screen may not be advisable in quicksand, especially if the aquifer's effective grain size is approxi-mately 0.004 inch. A naturally developed well completed with a screen having a slot as narrow as 0.005 inch may be preferable, allowing 50 to 60 percent of the aquifer to be developed slowly and carefully through the screen. A case history comparing two well design methods is presented.Both cable-tool and rotary sampling methods in quick- sands are discussed. The techniques are basically similar, whether the material is “quick” or stable.

Notes: A map should treat the critical problems in a way understandable to the intended reader. Some maps appropriately show only one or two pertinent hydrogeologic parameters. Point-data maps make little or no interpretation of the data. Four-dimensional maps-those that include an elapsed span of time or projection of hydrogeologic variables into the future-represent a high degree of interpretation of data; they are most useful to the map reader. The hydro-geologist has an obligation to his reader to design maps that are as useful as possible.

Notes: In this paper a way of estimating the probable character of the water in sand aquifers is explained with examples. Comparative chemical quality of water from many types of sand formations generally encountered during drilling may be predicted with considerable accuracy by observing the color of an aquifer sand and its depth. This approximate method of “guessing” water chemistry, if properly used, can do much to guide the water well contractors. It may often fail due to incorrect application of the technique rather than a failure of the technique.