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Source-linked reports with geographic coverage including Idaho.

At least 1,009 records · Page 56Linked to original sources

Ground water in the Raft River Basin, Idaho, with special reference to irrigation use, 1956-60

In the Raft River basin in south-central Idaho, ground-water withdrawals for irrigation have more than doubled since 1955, when data were compiled for a comprehensive report on the area. The present report summerizes data on the ground-water use and changes in the water regimen during the intervening 5 years. Water levels have declined 10 to 20 feet in the areas of heaviest pumping and 3 to 5 feet throughout the remainder of the area. These water-level declines are related to increased ground-water pumpage and below-normal precipitation in the basin. The total pumpage during the 1960 irrigation season is estimated to be about 127,000 acre-feet, of which about half was consumed by crops or evaporated. The remainder returned to the aquifer. Irrigation development is acting to reduce the amount of underflow out of the basin. The water table can be lowered considerably more before underflow from the basin would be reduced substantially.

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Temperature of crystallization of pyrrhotite and sphalerite from the Highland-Surprise Mine, Coeur d'Alene district, Idaho

The ore bodies of the Highland-Surprise Mine are replacements along shear zones in quartzose slate, quartzite, and phyllite of the Prichard Formation of the Belt series (Precambrian). Pyrite, arsenopyrite, pyrrhotite, sphalerite, chalcopyrite, and galena are the chief metallic minerals and were probably deposited in that order. Temperatures of formation were estimated for pyrrhotite-pyrite and sphalerite-pyrrhotite assemblages contained in the steeply dipping vein system. Measurements on 62 pyrrhotites indicate a range in temperature of crystallization between 370 degrees and 492 degrees C. (no correction required for confining pressures <2000 bars below 670 degrees C.), and measurements on 14 sphalerites indicate crystallization temperatures between 375 degrees and 460 degrees C. (uncorrected for confining pressure). No systematic temperature gradients were recognized. Minor elements in 23 pyrrhotite, 8 pyrite, 13 sphalerite, and 2 galena samples were determined. Partition ratios of Ni and Co in pyrrhotite-pyrite and sphalerite-pyrrhotite pairs are erratic. This suggests a dis-equilibrium distribution of these elements between the phases of each mineral pair and/or b) crystallization of the mineral pairs under different physical conditions.

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Late cenozoic structure of west-central Idaho

The massive Salmon River Mountains of interior Idaho are bounded on the west by a belt 30 miles wide of post-Miocene, west-tilted normal-fault blocks and west-dipping monoclines. The belt is coincident with the western border zone of the middle Cretaceous Idaho batholith, as it extends from the west edge of the massive interior of the batholith to about the western limit of the border zone of gneisses and schists. West of this belt is the Columbia Plateau province of irregular domal and anticlinal uplifts and northwest-trending normal faults. These structures are superimposed upon east- to northeast-trending, low-grade metamorphic rocks intruded by semi-concordant stocks and small batholiths, products largely of Late Jurassic (?) orogeny. The Idaho batholith has been little deformed, and its border-zone rocks of intermediate competence are broken by concordant structures. Young structures cut directly across the relatively incompetent rocks of the older orogen to the west. The mountains flanking the Snake River and Salmon River canyons are higher than those farther away, suggesting that local isostatic uplift may be compensating for their erosion.

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Paleozoic seas of central Idaho

Some recent paleogeographic maps indicate that central Idaho was part of a major geosyncline throughout Paleozoic time. This concept, apparently based on thick marine accumulations far apart on the margins of the region, is inconsistent with field data. Within the area of the Idaho batholith, Permian(?) volcanic rocks rest either on batholithic rocks or on the Belt Series. The Belt Series rocks have furnished the xenoliths in the batholith. To the west upper Paleozoic and Mesozoic strata are invaded. Along the eastern margin, south of lat. 45°, thick Paleozoic strata are intruded by the batholith. These locally exceed 30,000 feet in thickness and thin eastward. They have many variations. Those close to the batholith, especially those high in the sequence, are regarded as of near-shore origin. The Paleozoic strata in southeastern Idaho , more than 17,000 feet thick, are broadly similar except that Cambrian strata there are thicker and more widespread. The part of central Idaho north of the vicinity of lat. 45° has no known Paleozoic strata. Northern Idaho has only a few outcrops of beds of Cambrian age. The differences in thickness and character between Paleozoic strata in south- central and southeastern Idaho and those in western Montana and Wyoming (less than 7500 feet thick) suggest a hinge line near the eastern boundary between Idaho and Montana with a shelf to the east and a trough to the west. In south- central Idaho this trough had a maximum width of 90 miles and a western shore roughly at the east margin of the batholith. This trough wedged out northward a little beyond lat. 45°. Thus the area of the present Idaho batholith has been a positive block since Precambrian time, comparable to but apparently of longer duration than the geanticline in northern Nevada. Any invasion of the positive block in Idaho by marine waters during the Paleozoic was local and brief, except perhaps along the western border. Uncertain correlations within the area of the batholith leave open the possibility of some deposition there early in Paleozoic time.

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Quaternary geology of the Bellevue area in Blaine and Camas Counties, Idaho

The Bellevue area covers about 350 square miles of a foothill belt between the Rocky Mountains to the north and the Snake River plains to the south. Complexly deformed impure quartzites and limestones of the Mississippian Milligen and Pennsylvanian-Permian Wood River formations were intruded by large bodies of quartz diorite and granodiorite along regional structures trending northwesterly; the intrusions are part of the Cretaceous Idaho batholith. Erosional remnants of the Challis volcanics, dominantly latitic to andesitic in composition and early(?) to middle Tertiary in age, rest unconformably on the older rocks. A sequence of Pliocene Rhyolitic ash flows and basaltic lava flows unconformably overlies the Challis and older rocks and is in turn unconformably overlain by olivine basalt of late Pliocene or early Quaternary age. The main valleys of the area, partly Erosional and partly structural in origin, are underlaind by late Quaternary olivine basalt flows (Snake River basalt) and intercalated lacustrine, fluvial, proglacial sediments. The Big Wood River, the master stream of the area, flows southward through a narrow steep-sided valley in the mountainous country north of the Bellevue area and debouches into a broad alluvial valley, the Wood River Valley, in the foothill belt. The valley has the shape of an isosceles triangle with a ten mile long, east-west base consisting of a ridge of Pliocene volcanics which separates the valley from the Snake River Plains to the south. The river now flows through a narrow gap in the southwest corner of the triangle. A similar, but wider, gap around the east end of the ridge was formerly occupied by the river. The river has been shifted back and forth between these two gaps at least four times during an interval in which six late Quaternary basalt flows erupted in the Bellevue area. Two of the flows caused direct diversion of the river and another was influential in bringing about a diversion on an aggradational fan upstream from the lava dam. Just prior to the Bull Lake stage the river, flowing out the east gap, was blocked but not diverted by the youngest basalt flow in the Bellevue area. During the proglacial aggradation, the river shifted widely on its fan and spilled alternatively out both the east and west gaps. After the Bull Lake stage, the west gap had an advantageous base level relative to the lava-blocked east gap, and the river cut down in the west gap. After the second, Pinedale, proglacial aggradation in the Wood River Valley, the west gap still maintained an advantageous base level, and the river again cut down in the west outlet valley where it remains today. Periglacial deposits completely dominate the sidestream valleys of the Bellevue area. They formed under a rigorous climate during the Pinedale stage, when slope erosion accelerated by frost activated processes caused aggradation of valley floors by local detritus. Even at present the larger sidestreams are so choked with detritus that the streams have not regained control of their valley floors. Recent basalt, comparable in age to the younger flows of the Craters of the Moon National Monument, spread from a rugged, cratered vent several miles south of the Bellevue area. Using degree of weathering, erosion, and soil development as a basis of comparison, this flow provides and end point for estimating the relative ages of the six late Quaternary flows in the Bellevue area.

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Ground-water reconnaissance in Round Valley, Custer County, Idaho

Round Valley in central Idaho contains alluvial deposits of Pleistocene and Recent age which yield adequate supplies of ground water for stock and domestic wells. The alluvial deposits are underlain by Challis Volcanics of Oligocene or Early Miocene age and a few wells obtain domestic and stock water from the basalt, iatite, andesite, and rhyolite which are the principal rocks in the Challis. Very crude estimates indicate that the average annual recharge to the alluvium and Challis Volcanics from precipitation and irrigation is 50,000 acre-feet. Geologic and well data suggest that sufficient ground water might be obtained for irrigation supplies at some places.

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Ground-water reconnaissance of the Sailor Creek area, Owyhee, Elmore, and Twin Falls Counties, Idaho

This reports evaluates the ground-water resources of about 1,000 square miles in the semiarid uplands south of the Snake River between Bruneau River and Salmon Falls Creek. The outcropping rocks are the Idavada Volcanics of Pliocene age, and the Idaho Group of Pliocene and Plieistocene age, consisting of the Banbury Basalt of middle Pliocene age and overlying predominantly sedimentary deposits of middle Pliocene through middle Pleistocene age. These rocks dip gently northward. The volcanic rocks are the best aquifers, but the yield of water from the sedimentary deposits is adequate for domestic and stock use. About 6,000 acre-feet of water is withdrawn annually from the Idavada Volcanics by 9 irrigation wells to irrigate about 3,000 acres. Only a few tends of acre-feet of water withdrawn from the other formations. The regional dip of the rocks induces weak artesian conditions in the volcanic rocks and somewhat higher artesian head in the sedimentary rocks. Estimated depth to water ranges from less than 250 feet to more than 750 feet, as shown in an accompanying map. The eastern part of the area appears to be more favorable for the development of ground water for irrigation than the western part because of better aquifers at shallower depth.

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Water supply for a fish hatchery site, Clearwater Valley, Idaho

A fish hatchery proposed for the lower Clearwater River basin would require a continuous water supply of 10 to 12 cubic feet per second. Limitations on maximum and minimum temperatures and on turbidity are such that a combination surface-and ground-water supply probably would be required. Six prospective sites were examined with respect to their water supply. The sites were at the mouths of Orofino, Jim Fork, Lolo, Lawyer, Clear, and Cottonwood Creeks. The geology and ground-water hydrology were studied to determine the potential ground-water supply at each of the sites. Spot measurements were made on the six tributary streams and comparative studies were made with records on nearby streams to determine probable minimum flows. Of the six sites studied, only one, at the mouth of Clear Creek, had a favorable potential for both surface-and ground-water supply. As an alternative to the Clear Creek site, a location along the South Fork Clearwater River near Kooskia might be considered.

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Late quaternary history of the snake river in the American Falls region, Idaho

While mapping the American Falls region, we found evidence that contributes to the middle Pleistocene to Recent history of the Snake River, and indirectly to the history of overflow of Lake Bonneville. Middle Pleistocene to recent rocks in the valley are mainly lacustrine and fluvial silts and clays, with some sand, gravel, basalt, and a few thin tuff beds. The formation of terraces can be correlated with events both up- and downstream. The Snake River was at least once, and possibly twice, dammed and diverted by eruptions of basalt, resulting in the formation of lakes and deposition of lacustrine beds. A rather flat-lying, thin, but persistent gravel at the base of one lake bed formation may represent a glacial period, possibly Illinoian, during which the Snake River had a large volume. Overflow of water from Lake Bonneville into the Snake River system, by way of the Marsh Creek-Portneuf valley, laid down a deltaic-fluvial deposit here named the Michaud Gravel. At this time the Snake River, greatly augmented by Lake Bonneville overflow, began to cut channels through and around a lava dam. Terraces between Aberdeen, American Falls, and Pocatello were formed during the existence of the lake in which the Michaud Gravel was deposited and by fluvial processes after drainage of the lake. At one stage in the downcutting, bars of huge basalt boulders were built across the mouths of abandoned spillways. Radiocarbon dating and geologic evidence from the area between Preston and Soda Springs, Idaho, suggest that basalt flows diverted the Bear River into Lake Bonneville, perhaps causing it to overflow. This diversion probably occurred about 33,000 years ago. This dating accords with events in the American Falls region.

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Gravity survey in the eastern Snake River Plain, Idaho — A progress report

A regional gravity survey in the eastern Snake River Plain was conducted in the early summer of 1961. Seven hundred and seven gravity stations were established between latitudes 42°15'N and 44°30'N between longitudes 111°30'W and 114°30'W. Three hundred and twenty-five of these stations were located in 2,700 square miles of the eastern part with an average density of one station per 8.3 square miles. The remaining 9,300 square miles were covered by several lines, with an average lineal density of one station per 2.0 miles. A simple-Bouguer gravity contour map has been made of the area by standard methods. The low gravity relief and broad high of the eastern Snake River Plain strongly contrasts with the high amplitude anomalies of the western plain. The major anomalies of the eastern plain consist of 1) a broad high, which is an extension of the large gravity highs of the western plain, 2) a set of elongated alternating lows and highs that trend normal to the axis of the eastern plain, 3) a series of small, local highs on the boundary of the plain, and 4) a prominent low centered over Mud Lake in the northern part of the surveyed area. The basalts of the eastern plain have probably filled troughs or valleys in an undulating subsurface floor rather than a large regional graben.

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Preliminary report on ground water in the Salmon Falls area, Twin Falls County, Idaho

The Salmon Falls area contains about 80,000 acres of irrigable land, of which about 30,000 acres receives some water from the distribution system of Salmon River Canal Co., Ltd. This system utilizes virtually all the available surface water. A substantial amount of surface water, estimated to be about 70,000 acre-feet annually, is lost by leakage from the reservoir and the distribution system. Some of this water could be salvaged by lining sections of the canal where excessive losses occur. Ground water has not been extensively developed in the area, but some successful irrigation wells furnished supplemental irrigation water. Recharge to the area is from precipitation on the area, seepage from peripheral streams, seepage losses from the reservoir and canal system, irrigation seepage, and ground-water underflow. Ground water leaves the area by undertow to the north and northwest, and eventually reaches the Snake River. The total mount of underflow from the area was estimated by three different methods to be 17,000, 100,000, and 170,000 acre-feet per year. The preliminary estimate of 100,000 acre-feet was derived by the inventory of recharge and is probably more accurate than the other two methods. Calculations, based on estimates of transmissibility computed from specific capacities of wells, suggest that there may be some channels or conduits of higher than average transmissibility through which a large part of the undertow leaves the area, Possibly 25 percent of the ground-water outflow could be intercepted by wells. However, in part of the area the depth to water may be excessive for economic development. Chemical analyses of 25 samples of ground water indicate that most of the water sampled is suitable for irrigation. The samples found least suitable were of water occurring at shallow depth, south and east of Hollister.

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