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R.W. Maclay

Publications and source records attributed to R.W. Maclay.

At least 19 recordsLinked to original sources
USGS2006

Geochemistry and ground-water movement in northwestern Minnesota

The relation between water quality and water movement within the ground-water reservoir may be better understood if studies of flow systems are used in conjunction with hydrochemical methods. Within small watersheds, local, intermediate, and regional flow systems may develop, depending upon the shape, the relief, and the thickness of the ground-water reservoir. Lateral and vertical variations of water quality in the ground-water reservoir reflect the difference in length of flow paths within a system. The relative ion concentration of the major ions in solution in ground waters change as water moves from recharge areas to discharge areas. These changes are used to interpret the direction and rate of ground-water movement. Ground-water types mapped in the Two Rivers watershed of northwestern Minnesota indicate that calcium bicarbonate type water occurs near the source of recharge and progressively changes to the sulfate type as water moves downgradient toward the discharge area. Local recharge areas are indicated by the greater penetration of calcium bicarbonate waters into the ground-water reservoir. The calcrum bicarbonate type water of surface streams during low flow indicates that water moves into the stream from the upper part of the ground-water reservoir. Chloride type water moves from the Paleozoic rocks and mixes with water in the glacial drift probably at places where permeable zones in the Paleozoic rocks are in contact with the overlying drift.

Minnesota↗
USGS1987

Simulation of flow in the Edwards Aquifer, San Antonio region, Texas, and refinement of storage and flow concepts

The Edwards aquifer is a complexly faulted, carbonate aquifer lying within the Balcones fault zone of south-central Texas. The aquifer is recharged mainly by streamflow losses in the outcrop area of the Edwards aquifer and is discharged by major springs located at considerable distances, as much as 150 mi, from the areas of recharge, and by wells. Groundwater flow within the Edwards aquifer of the San Antonio region was simulated to investigate concepts relating to the storage and flow characteristics. A general purpose, finite difference model, modified to provide the capability of representing barrier faults, was used to simulate groundwater flow and storage in the aquifer. The simulations investigated the effects of complex geologic structures and significant changes in transmissivity, anisotropy, and storage coefficient, with initial values based on concepts developed in previous studies. Results of the simulations confirmed the original estimates of transmissivity values (> 100 sq ft/sec) in the confined zone of the aquifer between San Antonio and Comal Springs. A storage coefficient of 0.05 in the unconfined zone of the aquifer produced the best simulation of water levels and springflow. A major interpretation resulting from the simulations is that two essentially independent areas of regional flow were identified in the west and central part of the study area. Flow from the two areas converges at Comal Springs. The directions of computed flux vectors reflected the presence of major barrier faults which locally deflect patterns of groundwater movement. The most noticeable deflection is the convergence of flow through the geologic structural opening, the Knippa gap, in eastern Uvalde County. A second significant interpretation is that groundwater flow in northeastern Bexar, Comal, and Hays Counties is diverted by barrier faults toward San Marcos Springs, a regional discharge point. (Lantz-PTT)

Texas↗
USGS1984

Carbonate geology and hydrology of the Edwards Aquifer in the San Antonio area, Texas

Regional differences in the porosity and permeability of the Edwards aquiifer are related to three major depositional areas, the Maverick basin the Devils River trend, and the San Marcos platform, that existed during Early Cretaceous time. The rocks of the Maverick basin are predominantly deep basinal deposits of dense, homogeneous mudstones of low primary porosity. Permeability is principally associated with cavernous voids in the upper part of the Salmon Peak Formation in the Maverick basin. The rocks of the Devils River trend are a complex of marine and supratidal deposits in the lower part and reefal or inter-reefal deposits in the upper part. Permeable zones, which occur in the upper part of the trend, are associated with collapse breccias and rudist reefs. The rocks of the San Marcos platform predominantly are micrites that locally contain collapse breccias, honeycombed, burrowed mudstones, and rudist reef deposits that are well leached and very permeable. The rocks of the San Marcos plat form form the most transmissive part of the Edwards aquifer in the San Antonio area. Karstification of the rocks on the San Marcos plat- form during Cretaceous time enhanced the permeability of the aquifer. Permeability of the Edwards aquifer is greatest in particular strata (lithofacies) which have been leached in the freshwater zone. Ground water moves along vertical or steeply inclined fractures that are passageways by which water can enter permeable strata. Water moves from the fractures into beds formed by collapse breccias, burrowed wackestones, and rudist grainstones that have significant secondary porosity and permeability. Water has selectively dissolved sedimentary features within those rocks to increase the size of the openings and the degree of interconnection between pore voids. Recognition of the hydrostratigraphic subdivisions provides a basis for defining the nonhomogeneity of the aquifer and determining its storage characteristics. The aquifer is considered to be a faulted and multilayered aquifer in which lateral circulation is mainly through very permeable, hydrostratigraphic subdivisions that are hydraulically connected at places by openings associated with steep-angle, normal faults. The Edwards aquifer is vertically displaced for its entire thickness at places along major northeastward trending faults. At these places, ground-water circulation is diverted either southwest or northeast.

Open-File Report↗
USGS1984

Compilation of hydrologic data for the Edwards Aquifer, San Antonio area, Texas, 1981, with 1934-81 summary

The average annual ground-water recharge to the Edwards aquifer in the San Antonio area, Texas, from 1934 through 1981, was 612,400 acre-feet. The recharge in 1981 was 1,448,400 acre-feet, which is the third highest annual recharge since 1934. A maximum annual recharge of 1,711,200 acre-feet occurred in 1958, and a minimum annual recharge of 43,700 acre-feet occurred in 1956. The calculated annual discharge by wells and springs in 1981 was 794,400 acre-feet. Annual discharge by wells and springs ranged from a maximum of 960,900 acre-feet in 1977 to a minimum of 388,800 acre-feet in 1955. The annual discharge by wells was 387,100 acre-feet in 1981. Although water levels in many of the wells in the Edwards aquifer fluctuated near the midpoint between record high and low levels during the first 5 months of 1981, the volume of ground water in storage in the aquifer was above average for most of the year. Analyses of water samples from 56 wells and 3 springs show that the water is of a significantly better quality than the level established for public water systems.

Texas↗
USGS1983

Hydrostratigraphic subdivisions and fault barriers of the Edwards aquifer, south-central Texas, U.S.A.

The karstic Edwards Limestone within the Balcones Fault Zone of south-central Texas forms a productive confined aquifer that consists predominately of dense carbonate rocks and contains several layers of highly permeable and porous honeycombed rocks that have been produced by the leaching of evaporitic, tidal flat or reefal deposits. Fractures have hydraulically interconnected these layers at some places. Faults, however, commonly place rocks of very high-permeability opposite rocks of very low permeability, thus creating a lateral discontinuity and a flow barrier. At places, fault barriers probably cause partial to almost complete blockage of groundwater flow normal to the fault.

Texas↗
USGS1980

Hydrochemical data for the Edwards aquifer in the San Antonio area, Texas

This report presents hydrochemical data that was collected as part of the investigations of the Edwards aquifer in the San Antonio area, Te xas, during 1970-78 and indicates other sources of available data. The report includes the results of chemical analyses of 159 water samples from 123 well s and springs; tritium analyses for 242 water samples from 120 wells and springs; isotope and redox-potential analyses of 31 water samples from wells, springs, and streams; and calculated dissolved carbonate, partial C02 pressures, and saturation indices of selected minerals in 98 water samples from 81 wells, springs, and streams. The water types and hydrochemical facies are given for six zones of the aquifer.

Texas Department of Water Resources Report↗
USGS1968

Water resources of the Mustinka and Bois de Sioux Rivers watershed, west-central Minnesota

The Mustinka and Bois de Sioux Rivers watershed is mantled by till deposits with scattered sand deposits. The west-central and northwestern part of the watershed was covered by Glacial Lake Agassiz and the resulting land surface is a flat, lake-washed till plain. Patches and ridges of sand scattered throughout the lake plain were formed as beach ridges and offshore bars. Small, isolated areas of lake clay also occur within this area. The remainder of the watershed is glacial moraine characterized by rolling topography in all but the extreme eastern edge which has more local relief and more permanent lakes. Alluvial sand deposits are found in the eastern part of the morainal area. The drainage area of the watershed in Minnesota is 1,429 square miles. The area includes mors of Traverse County and parts of Big Stone, Stevens, Grant, Ottertail, and Wilkin Counties. Population within the watershed unit is about 20,000. The largest community, Wheaton, has a population of 2,102. The agricultural economy of the area is concentrated on grain farming, although some dairying is carried on. The principal grain crops are corn and oats. Flax, soybeans, and barley are also very commonly grown. The natural vegetation in the area was largely prairie. A hardwood deciduous forest grew only on the extreme eastern edge. Today, the area is almost entirely farm land containing numerous local woodlots. Outdoor recreation is concentrated on waterfowl and pheasant hunting. Fishing is done in Lake Traverse and in the larger lakes in the eastern part of the morainal area.

Minnesota↗
USGS1967

Water resources of the Two Rivers Watershed, Northwestern Minnesota

The Two Rivers watershed includes two physiographic areas a lake plain and a till plain – within its 1,232 square miles. It lies in parts of Kittson and Roseau counties and includes the drainage basins of the Two Rivers and Joe River. The flat lake plain which extends 15 to 20 miles east of the Red River of the North is extensively cultivated for small grains and sugar beets. The gently undulating till plain is cultivated largely for small grains and hay. The areas not under cultivation support a forest of poplar with some maple and oak. Oak is the predominate tree on the sandy ridges. The large peat areas are covered with brush and marsh grasslands. Outdoor recreational facilities in the watershed consist principally of the Lake Bronson Park, water-fowl hunting in the extensive marshlands, and deer and small game hunting in the forested areas.

Minnesota↗
USGS1967

Water resources of the Roseau River Watershed, Northwestern Minnesota

The drainage area of the Roseau River consists of 2,060 square miles above its confluence with the Red River of the North. About 1,150 square miles lie in the United States and 910 square miles in Canada. This report deals only with that portion within the United States, except for a detailed analysis of low flow characteristics of tributary streams. Most of the area is within Roseau County, but small portions are in Marshall, Beltrami, Lake of the Woods, and Kittson Counties. Most of the watershed has little relief, and lies entirely within the plain of former Glacial Lake Agassiz. However, the flat topography of this lake washed till plain is broken by beach ridges in its southwestern part and Beltrami Island, a topographic high underlain by sand, in tis southeastern part. Population within the watershed is about 8000. The town of Roseau, the largest community, has a population of 2146 (1960). The watershed has an agricultural economy. Spring wheat, oats, and bluegrass seed are the three most important crops in the area, but many other small grains, legumes, and grasses are also grown. Dairy farming and sheep raising are the most important types of livestock production and for many farms stock is the major sources of income. Large areas of the watershed are peat lands, covered with shrubs, marsh grasslands, and spruce, tamarack, and cedar trees. Forest vegetation in the remainder of the area is largely aspen, but oak is common on the beach ridges and jack pine is common on Beltrami Island. Outdoor recreation in the area is primarily hunting of deer, small game, and waterfowl. This report is a general appraisal of the water resources in the Roseau River watershed unit. Detailed studies of water movement through the ground-water reservoir are needed for more exact determination of the amount of water immediately available and the specific effects of water-management practices.

Minnesota↗