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The Colorado River Basin faces the dilemma of an increasing demand for water while presently struggling with salinity concentrations approaching critical levels for some water uses. Based upon projected development salinity concentrations are predicted to exceed 1200 mg/1 at Imperial Dam by the year 2010. Annual losses to the basin economy associated with increased salinity will exceed $50 million by the year 2010. Although methods of controlling salt discharges are relatively unrefined, certain conclusions, based upon Bayesian statistical methods, can be reached. Five basic alternatives for coping with the problem are presented and evaluated in this paper: (1) do nothing; (2) adopt arbitrary salinity standards;...
As the earth becomes a quilt of managed patches, ecohydrologists need to move from describing to predicting the consequences of human activities, using knowledge to improve human well-being. We highlight three current opportunities in ecohydrology. The first is the need for stronger research in arid and semi-arid ecosystems, where water is scarce and a tight coupling exists between hydrology and ecology. The second is to build better predictive frameworks for understanding the consequences of vegetation change. The new framework we propose here combines landscape connectivity, through recharge and discharge dynamics, with global climate. In systems where annual precipitation and evapotranspiration are similar, the...
Regional transport of water and dissolved constituents through heavily regulated river systems is influenced by the presence of reservoirs. Analysis of seasonal patterns in solute fluxes for salinity and nutrients indicates that in-reservoir processes within large storage reservoirs in the Rio Grande and Colorado basins (southwestern USA) are superimposed over the underlying watershed processes that predominate in relatively unregulated stream reaches. Connectivity of the aquatic system with the landscape is apparently disrupted by processes within the reservoir systems; these processes result in large changes in characteristics for solute transport that persist downstream in the absence of significant inputs. Additionally,...
To determine habitat attributes and processes suitable for the growth of Coccidioides, soils were collected from sites in Arizona, California, and Utah where Coccidioides is known to have been present. Humans or animals or both have been infected by Coccidioides at all of the sites. Soil variables considered in the upper 20 cm of the soil profile included pH, electrical conductivity, salinity, selected anions, texture, mineralogy, vegetation types and density, and the overall geomorphologic and ecological settings. Thermometers were buried to determine the temperature range in the upper part of the soil where Coccidioides is often found. With the exception of temperature regimes and soil textures, it is striking...
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Predawn plant water potential (Ψw) is used to estimate soil moisture available to plants because plants are expected to equilibrate with the root-zone Ψw. Although this equilibrium assumption provides the basis for interpreting many physiological and ecological parameters, much work suggests predawn plant Ψw is often more negative than root-zone soil Ψw. For many halophytes even when soils are well-watered and night-time shoot and root water loss eliminated, predawn disequilibrium (PDD) between leaf and soil Ψw can exceed 0.5 MPa. A model halophyte, Sarcobatus vermiculatus, was used to test the predictions that low predawn solute potential (Ψs) in the leaf apoplast is a major mechanism driving PDD and that...
Colorado squawfish (Ptychocheilus lucius), were subjected to dilutions of saline water from natural springs near Glenwood Springs, Colorado, to determine salinity tolerance and aquaculture potential of squawfish in this water. Lethal salinity to 50 percent of the fish (96 h LC50) was 13.1 g l?1, indicating that squawfish survival in higher salinity spring water was not possible. Published in Hydrobiologia, volume 657, in 1992.
The Price River is a significant contributor of salt to the Colorado River. Relatively pristine waters leaving the upper elevations of the basin degenerate into highly saline waters entering the Green River. The primary reason for this deterioration is the contact of the water with the Mancos shale, a marine deposit underlying most of the central basin. This paper presents the structure of an evolving model of the salt pick-up and transport processes in the Price River basin. The initial purpose of the model is to aid in the identification of the natural and man-modified hydro-salinity-sediment system of the basin, based on data collection and analysis in the field and the laboratory. This identification procedure...
A study was performed to identify sources of solute loading to the Dirty Devil River and its major tributaries, in southeastern Utah. A primary goal was to determine the contribution of gypsum dissolution to total dissolved solids concentration, and its potential increase in the future if salinity control measures are instituted. Synoptic field data were collected during the low flow period in October 1983. Data were analyzed using the geochemistry models WATEQF and BALANCE to postulate mineral reactions leading to solute loading. Three known sources of solute loading, involving two different geochemical mechanisms, were clearly discernable. Two additional areas of possible gypsum dissolution were located. Published...
Dissolved mineral salts (salinity) adversely affects numerous urban and agricultural users of Colorado River water in southwestern United States and in Mexico. More than a third of the salt load is thought to be induced by drainage from irrigated lands onto highly saline groundwater deposits in the Upper Colorado Basin in Colorado, Utah, and Wyoming. Various public policy initiatives are proposed to induce farmers to reduce discharges of this nonpoint pollutant. Taxes on water, water conservation subsidies, and land and water rights purchases are analyzed in a linear programming framework. The allocative efficiency and the distribution of control costs and damages among irrigators, water users, and taxpayers are...
Water development in the Green River Basin of Wyoming is projected to increase salinity downstream in the Green River and Colorado River, and thereby increase salinity costs to users of water from these two rivers. Despite these water quality and economic impacts to downstream water users, Wyoming will probably be able to develop its currently unused but allocated water supplies of the Green River Basin. The Colorado River Compact and Upper Colorado River Basin Compact are binding, and protect Wyoming's share of the Colorado River System waters for future use. The argument that water may be used to greater profit downstream is not sufficient to reduce Wyoming's allocation. In addition, the no-injury rule under the...
Restoration of salt-affected soils is a global concern. In the western United States, restoration of salinized land, particularly in river valleys, often involves control of Tamarix, an introduced species with high salinity tolerance. Revegetation of hydrologically disconnected floodplains and terraces after Tamarix removal is often difficult because of limited knowledge regarding the salinity tolerance of candidate native species for revegetation. Additionally, Tamarix appears to be non-mycorrhizal. Extended occupation of Tamarix may deplete arbuscular mycorrhizal fungi in the soil, further decreasing the success of revegetation efforts. To address these issues, we screened 42 species, races, or ecotypes native...
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Populus fremontii (Fremont cottonwood) was once a dominant species in desert riparian forests but has been increasingly replaced by the exotic invasive Tamarix ramosissima (saltcedar). Interspecific competition, reduced flooding frequency, and increased salinity have been implicated in the widespread decline of P. fremontii. To elucidate some of the multiple and interacting mechanisms of this decline, we examined ecological processes in a control stand of P. fremontii along the Colorado River in Utah, USA, as well as a disturbed stand characterized by high groundwater salinity and invasion of T. ramosissima. Sap flux data showed that P. fremontii at the saline site experienced large reductions in afternoon canopy...
The Colorado River Basin, poor in water and rich in energy resources, is examined to see if water quality can be sustained for U.S. and Mexican users. Activities to mine, process, transport, and convert resources to energy and to reclaim the land all require water, although development is expected to continue in spite of uncertainties. Projections of water requirements for different energy sources are summarized for the 1990-2000 time period. Restrictions on water supply derive from both quantity limitations and such institutional barriers as water rights and contracts. Projections of the sources and occurrences of salinity levels and pollutants are detailed for each section of the Basin. Salinity is concluded to...
he Mancos Shale area of the Upper Colorado River basin produces large quantities of solutes. In order to develop an understanding of the mechanism of salt production and to determine the source of salinity, a study of the soluble mineral content (SMC) of Mancos Shale and associated alluvium was undertaken. SMC is highly variable in alluvium and associated surficial Mancos Shale. However, lithomorphological units can be identified in terms of their SMC. Results from this study demonstrate that crusts are leached in deep alluvial fills and they contain somewhat less soluble minerals than underlying Mancos Shale on hillslopes. The crusts are saline, sometimes efflorescent, in shale bedrock channels or where channels...
Natural and anthropogenic changes in basin lake levels in the western U.S. expose saline, alkaline substrates that are commonly colonized by shrubs in the Chenopodiaceae. On a chronosequence of recently exposed substrates at Mono Lake, California, Sarcobatus vermiculatus has greatest biomass accrual, seed production, seedling establishment, and leaf N at younger sites where soils are extremely saline and alkaline. These field observations and an understanding of the role of N-containing compatible solutes in salinity tolerance of halophytes led to our prediction that Na and N interactions stimulate Sarcobatus performance. To test this, we grew Sarcobatus juveniles for 2 years in the greenhouse at 4 levels of NaCl...
In the western United States many rivers experience high salinity resulting from natural and anthropogenic sources. This impacts the water quality and hence, is closely monitored. The salinity is closely linked with streamflow quantity in that, a higher flow brings with it more salt but also provides substantial dilution to reduce the salt concentration and vice-versa during low flow regimes. Decision makers typically plan strategies for salinity mitigation and evaluate impacts of water management policy options on salinity in the basin using decision support models. These models require statistically consistent basin wide scenarios of streamflow and salinity. Recognizing this need, we develop a basin wide stochastic...
Relative yields of water, sediment, and salt (as indexed by electrical conductivity) were determined using simulated rainfall plots on three soil landform units on Mancos shale in the Price River Basin, Utah. Final infiltration rates on residual shale derived soils were between 0.13 and 0.50 cm/hr. No runoff was generated on cracked soils derived from aeolian deposits. Suspended sediment concentrations and elehcal conductivities were 180 and 68 times greater, respectively, for a steep dissected Mancos shale upland than for a low relief shale pediment and recent alluvial surface. Riling accounted for approximately 80 percent of the sediment produced on the steep, dissected shale surface. Channel scow and soil creep...
Investigations of vegetation stress along non-paved roads treated with a range of magnesium chloride (MgCl2) application rates utilized 60 roadside and 79 drainage plots on 15 and 18 roads, respectively. Evaluations were completed of foliar damage, plant health, biotic and abiotic damage incidence and severity, soil and foliar chemistry and other common site and stand characteristics of Pinus contorta, Populus tremuloides, Picea engelmannii, Abies lasiocarpa, and lower elevation plots dominated by shrubs and grasses. High concentrations of soil magnesium and chloride (400?500 ppm), high foliar chloride (2,000?16,000 ppm depending on species) and high incidence of foliar damage were measured in roadside plots along...
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Salinity increases in water in some parts of the Nava-jo aquifer in southeastern Utah have been documented previously. The purpose of this paper is to use bromide, iodide, and chloride concentrations and del oxygen-18 and deuterium values in water from the study area to determine if oil-field brines (OFB) could be the source of increased salinity. Mixing-model results indicate that the bromide-to-chloride X 10,000 weight ratio characteristic of OFB in and outside the study area could not be causing the bromide depletion with increasing salinity in the Navajo aquifer. Mixing-model results indicate that a mixture of one percent OFB with 99 percent Navajo aquifer water would more than double the bromide-to-chloride...
This study emphasized a field investigation of salt release to overland flow from Mancos shale lands of the Price River Basin, Utah. Although a high degree of natural variation existed in the data, which precluded the separation of factors affecting diffuse salt loading that occurs during overland flow, a simplistic nonpoint source loading function developed on empirical concepts was fit to the data. This function was then used to calculate the average annual salt yield to the Price River by overland flow. It was found that even under severe conditions, the salt yields from Mancos shale lands due to overland flow is relatively minor, accounting for less than 1.5 percent of the average annual salt mass transported...
map background search result map search result map Salinity increases in the Navajo Aquifer in southeastern Utah High apoplastic solute concentrations in leaves alter water relations of the halophytic shrub, Sarcobatus vermiculatus Ecohydrology in a Colorado River riparian forest: implications for the decline of Populus fremontii Ecohydrology in a Colorado River riparian forest: implications for the decline of Populus fremontii High apoplastic solute concentrations in leaves alter water relations of the halophytic shrub, Sarcobatus vermiculatus Salinity increases in the Navajo Aquifer in southeastern Utah