Texas Water Resource Institute

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The 1997 Irrigation Suspension Program for the Edwards Aquifer: Evaluation and Alternatives
(Texas Water Resources Institute, 1998-02) Ward, Ruby; Chen, Chi Chung; McCarl, Bruce A.; Keplinger, Keith O.
The EAA implemented a pilot irrigation suspension program in 1997 on 9,669 acres mainly in Medina and Uvalde counties with the objective of increasing springflow at Comal Springs, and providing relief to municipalities in meeting Critical Period (drought) Management Rules. The Aquifer region, however, experienced a wet Spring in 1997, so that even irrigators not enrolled in the program applied little or no irrigation water. If conditions were dry in Spring 1997, aquifer simulation results indicate that suspending irrigation on enrolled acreage would have reduced pumping by 23,206 acre-feet and would have augmented Comal springflow by 6,498 acre-feet during the program year and by 17.7 cfs in August. The level of the eastern portion of the Aquifer would have been expect to rise by about 3.8 feet, and the cost per acre-foot of suspended irrigation would have been about $99. Payments to irrigators totaled $2,350,000. The ISP Program did cause farmer adjustments. Participants in the ISP program planted less corn, cotton, vegetables, and peanuts in favor of more sorghum and wheat. Irrigators who converted to dryland purchased somewhat less fertilizer, seed, and labor, but secondary effects on the local economy appeared to be small. The price paid per suspended acre was much higher than regional lease rates and average cropping profit margins in many instances. Factors which may have accounted for the high bids include: 1) lack of experience with an ISP, 2) its late start up, 3) the belief that bids might affect future water prices or offers, 4) tendencies to bid high enough to cover costs under a worst case scenario of a total loss of dryland crops, 5) collusion and need to bid high enough to compensate all under current land lease arrangements. Bids in future ISP solicitations might be lower, or might not. Given the substantial difference between local irrigated land rental rates and ISP bids, it seems unlikely that the EAA could attract sufficient acreage by capping bids at rental rates. There may be, however, some latitude for the EAA to set a maximum per acre rate somewhere between local rental rates and the ISP bids. This, combined with announcing the program and executing contracts in October or November, has the possibility of substantially reducing program cost. The EAA may also want to consider offering an option contract which when implemented would suspend irrigation in April or May. Waiting until April or May would provide the EAA more information on current year weather allowing better information on whether irrigation suspension is really necessary since: 1) more time would have elapsed allowing administrators to know Aquifer elevation at a later date, and 2) information of weather, irrigation use to date and projected irrigation for the remainder of the cropping year is increased this point. The cost of a single implementation of such a program may be substantially higher than a January 1 contract, since irrigators may sustain greater loss. Expected program cost, however, could be lower, since this option would be exercised less frequently, offsetting over higher cost of implementation. Good alternatives to an ISP are limited. We evaluated the potential of 1) implementing more efficient irrigation technology and 2) buying land and leasing it back during wet or average years. The ISP is a more cost effective source of critical water than is the use of subsidized irrigation efficiency largely because the ISP can put in place only when water is needed. Also, while not considered here, evidence in areas such as the High Plains suggests that irrigator pumping is not reduced by the amount an increase in irrigation efficiency would imply. This is because irrigators may choose to irrigate more water intensive crops and/or irrigate more acreage when efficiency is increased. The high bids experienced in the 1997 program compared to price of land in the Aquifer region suggests that a buy-leaseback arrangement could substantially reduce the cost to the EAA of suspending irrigation. This, of course, would require an alternate set of administrative costs by the EAA and may be less expensive than the ISP. Also the picture may be altered by the adjudication of water rights in the Aquifer which will likely be finished within three to five years. After water rights adjudication, however, buying and leasing back water rights may be a very appropriate and cost effective strategy for the EAA. In sum, we conclude that the 1997 pilot ISP was a reasonable response to the drought condition experienced in 1996. Fine-tuning the selection criteria, bid arrangement, allowing greater lead time, and/or implementing an ISP or option contract later in the year, holds the potential for reducing the cost of program implementation. A land-based ISP is an interim arrangement that can be implemented in the absence of a fully functioning permit system. After water rights are adjudicated in the region, ISP and option contracts will take on more conventional forms involving buy, lease, and option contracts for water rights. It is expected that water-based versus land-based arrangements would likely facilitate the transfer of water at lower rates.
2009 International SWAT Conference Conference Proceedings
(Texas Water Resources Institute, 2009-08)
Acute and Genetic Toxicity of Municipal Landfill Leachate
(Texas Water Resources Institute, 1991-10) Donnelly, K.C.; Schrab, G.E.; Brown, K.W.
Municipal solid waste (MSW) landfills have been found to contain many of the same hazardous constituents as found in hazardous waste landfills. Because of the large number of MSW landfills, these sites pose a serious environmental threat to groundwater quality. This study was conducted to assess the environmental hazards that materials leaching from four MSW landfills pose to groundwater supplies. Four leachate and one upgradient groundwater samples were collected from landfills selected to be representative of landfills of differing ages and types of wastes. Each sample was tested through three genetic toxicity bioassays (The Aspergillus diploid assay, the Bacillus DNA repair assay and the Salmonella/microsome assay) to measure the ability of each sample to induce mutations in bacteria, bind to microbial DNA, or cause chromosome damage in diploid fungi. Genetically toxic chemicals may cause cancer, genetic disease, sterility, abortions, heart disease or a variety of other chronic effects. These chronic effects can be subtle and may not appear for decades after exposure. In addition to the three genetic toxicity assays, each sample was tested in the Microtox test to measure acute toxicity. This assay is a measure of the ability of the sample to cause cell death. Organisms exposed to elevated levels of acute toxins may express the toxic effects through organ disfunction or the complete death of the organism. Each sample was chemically analyzed using GC/MS techniques and the chemical concentrations were used to calculate a chemical based risk assessment which is an estimate of the potential carcinogenic health effects associated with the mixture of chemicals in the sample. All four leachate samples exhibited acute toxicity in the Microtox test. Leachate from landfills representative of both an old unlined landfill which received residential waste and a new operating landfill receiving residential waste contained concentrations of some priority pollutants in excess of promulgated standards for drinking water. Chemical based risk assessments for these same two leachates showed them to have mean and 98th percentile cancer risks of 1 in a thousand (10-3) which is greater than both leachate from a Superfund landfill and leachate from the Love Canal landfill. The results of the acute and genetic toxicity bioassays, combined with the chemical analyses and associated cancer risk assessment clearly showed that leachate from municipal solid waste landfills is just as toxic as that which leaches from landfills where residential and hazardous wastes were codisposed.
Afghan Ambassador
(Texas Water Resources Institute, 2007) Wythe, Kathy
Agencies Approve Bacteria TMDL Task Force Recommendations
(Texas Water Resources Institute, 2007) Wythe, Kathy
The Agricultural Benefits of Salinity Control on the Red River of Texas and Oklahoma
(Texas Water Resources Institute, 1980-12) Moore, D. S.; Lacewell, R. D.; Laughlin, D. H.
Salinity of the waters from the Red River and its major tributaries has virtually eliminated its use for irrigation of agricultural crops in Texas and Oklahoma. A chloride control project has been proposed whereby the source salt waters will be captured and diverted to storage facilities. The purpose of this study was to estimate the net direct benefits to agricultural producers attributable to the proposed salinity control project. Further, estimates of project costs, municipal and industrial benefits and benefits from improving the water in Lake Kemp were obtained to complete a benefit-cost analysis. The procedure used to estimate agricultural benefits was to use a FORTRAN program to develop initial tableaus of a recursive linear programming model representing agricultural production in the study area. Alternative scenarios involving profit maximizing behavior on the part of producers, current cropping patterns, and with and without SAR crop yield effects were developed to provide a range of benefit estimates. The basis for benefit evaluation was to use parameters prescribed by the U.S. Water Resources Council's Principles and Standards and recent proposed changes along with those developed in this study to estimate the increase in net returns to producers in the study area between a with project and a without project condition for a 100 year period of analysis. Benefits were discounted to their present value with discount rates of 7 1/8 percent and 3 1/4 percent for comparative purposes. Benefits estimated herein were used in conjunction with external estimates of project costs and other benefits to evaluate the economic feasibility of the salinity control project. In all scenarios considered, cotton emerged as the major irrigated X crop. Scenarios involving profit maximizing behavior on the part of producers resulted in benefit estimates of over $65 million and $117 million without and with SAR crop yield effects, respectively, at the 7 1/8 percent discount rate. Under a constrained profit maximization scenario where SAR crop yield effects were included and in which producers were assumed to keep current cropping patterns in 1990, adjust to 50 percent of the optimal land use in 2000, and were fully adjusted to optimal land use by 2010, resulted in agricultural benefit estimates of over $87 million at the 7 1/8 percent discount rate. In a scenario where producers were assumed to maintain current cropping patterns throughout the 100 year period of analysis, benefits were estimated to be $28.8 million and $35.8 million without and with SAR crop yield effects, respectively, at the 7 1/8 percent discount rate. Benefit-cost analysis performed in this study indicated that the proposed project was economically feasible under assumptions of all scenarios considered except where current cropping patterns were followed for the entire analysis period. B/C ratios of 1.068 and 1.291 resulted for the profit maximization scenarios without and with SAR crop yield effects, respectively. Where benefits from the constrained scenario were included in the benefit-cost analysis, a B/C ratio of 1.162 resulted. Finally, with current cropping patterns maintained through 2090, B/C ratio estimates Of .907 and .938 resulted without and with SAR crop yield effects included, respectively.
Alternative energy must consider water needs
(Texas Water Resources Institute, 2009) Wythe, Kathy
Alternative water sources: Desalination model provides life-cycle costs of facility
(Texas Water Resources Institute, 2009) Supercinski, Danielle
An Analysis of the Effects of Sociodemographic Factors on Daily Per Capita Residential Water Use in Texas Cities
(Texas Water Resources Institute, 1988-02) Parpia, Banoo; Bachman, Kenneth; Hamm, Rita R.; Albrecht, Don E.; Murdock, Steve H.
Water is a key resource of concern to residents and decision makers in the State of Texas and in many other parts of the United States. Careful planning for its use is of utmost importance for the State and the Nation. Such planning requires careful consideration of numerous factors including hydrologic and physiographic factors, engineering feasibility and economic feasibility. At the same time, it is increasingly evident that water needs are closely tied to population growth and to the social, economic and demographic characteristics of the population (Murdock et al., 1985). Thus, attempts to plan for the use of water resources have become increasingly inclusive of socioeconomic as well as physical variables as the costs of incorrectly projecting water demand and misallocating funds for facility construction and management have become apparent (Stees et al., 1976; McFarland and Hyatt, 1973; Reid, 1971; Texas Department of Water Resources, 1984). To date, however, water-related socioeconomic research has concentrated on: 1. water use policy and water use planning 2. the demographic and social correlates of water and other resource use 3. the effects of water use and availability on demographic and social patterns 4. methodologies for projecting demands for resources and the implications of the use of resources An extensive body of research addresses both the need for, and the dimensions that must be considered in, water use policy formation and planning (Markusen, 1978; U.S. Water Resources Council, 1978; Council for Agriculture Science and Technology, 1982; National Water Commission, 1973; Office of Technology Assessment, 1983; Texas Department of Water Resources, 1984). Such analyses persuasively argue for the use of comprehensive, multidisciplinary planning formats, but as several recent reviews of water resources research efforts have noted (Francis, 1982; Napier et al., 1983), much of the basic research necessary to establish the relationships that should form the bases of the information used in such planning has not been completed. The demographic and social correlates of water use have not been sufficiently established. Although total population and demographic structure characteristics are often used in projecting demands for water resources (Mercer and Morgan, 1978; Texas Department of Water Resources, 1984), several recent efforts evaluating the use of demographic and social variables in water use planning have noted that few of the relationships between demographic and social factors and water use have been established empirically (Murdock et al., 1985; Korsching and Nowak, 1983; Francis, 1982). Thus, it is unclear what effects differences in household or family composition patterns or the age structure of a population have on usage of water and related resources. In like manner, although given some attention in the literature (Larson and Hudson, 1951; Bogue, 1963; Kubat et al., 1968; Francis, 1982; Napier et al., 1983), the relationships between such crucial social variables as socioeconomic status, ethnic status and perceptions of water conservation requirements and water use have not been adequately examined. Since other resource uses, such as energy use (Morrison, 1976), show substantial variation across demographic, social and cultural variables, similar effects are likely to be found between demographic, social and cultural variables and water use. The effects of water use and availability on population and social patterns have been given considerable attention (Williford et al., 1976; Doeksen and Pierce, 1976; Albrecht et al., 1984; Murdock et al., 1984; Albrecht and Hurdock, 1985). Such analyses suggest that changes in water resource availability or in the use of water-related forms of technology may lead to substantial changes in the population bases of areas (Albrecht and Murdock, 1985; Fitzsimmons and Salama, 1977) and may lead to related economic and community service changes (Williford et al., 1976). However, such analyses have tended to use only general and very unrefined assumptions concerning the relationships between water availability, use and technology and demographic and social factors. An extensive body of research has also developed related to the modeling of economic and demographic factors associated with resource use and development (Leistritz and Murdock, 1981; Murdock and Leistritz, 1980; Ford, 1976; Stenehjem and Metzger, 1976; Dunn and Larson, 1963; Nercer and Morgan, 1978). Although such models have become increasingly complex, several recent reviews of these models suggest that validation of the parameter assumptions underlying them is needed (Leistritz and Murdock, 1981; Markusen, 1978). In particular, most such models project water demand and use on the basis of per capita or per population unit factors. Population composition is not taken into account. Overall, then, although a few studies have attempted to include demographic variables--age, household size and patterns, race/ethnicity-and social, cultural and behavioral variables--such as water use preferences and cultural patterns of water use--in planning and projection efforts (Kubat et al., 1968; Dunn and Larson, 1963; Korsching and Nowak, 1983; Portney, 1982), water planning and analyses efforts have largely ignored the effects of demographic factors (other than total population size) and social factors in planning for water use and facility construction. Such neglect is particularly unfortunate in states, such as Texas, where populations display wide demographic and social diversity (Skrabanek et al., 1985) and where per capita water use varies widely from one area to another (Texas Department of Water Resources, 1984). Only if analyses of the relationships between demographic and social variables and water use and demand are completed, will it be possible to adequately employ such variables in projections of water demand. Because the inclusion of such variables in projection models should increase the accuracy of projections and improve our understanding of the numerous factors that determine patterns of water use, studies of the effects of demographic and social factors on water use and on projections of water demand deserve additional consideration. This report presents the results of one such study sponsored by the Texas Water Resources Institute. The study has two major objectives: 1. to determine the relationships between key demographic, social and cultural variables and water use in Texas 2. to analyze the implications of the relationships between demographic, social and cultural variables and water use and demand for projections of water use and demand in Texas Specifically, this report presents the results of an analysis of secondary and primary data in which the relationships between water use and other sociodemographic variables are examined, and it reports the effects of using sociodemographic characteristics to project water use. These relationships are of intrinsic interest to professionals involved in water planning and policy formulation, and the results will hopefully be of utility to a wide range of policy and decision makers. The report is organized into five sections. Section I describes the data and methodologies employed in the analysis. Section II presents and discusses the results of the secondary analysis. Section III examines the results of our analysis of survey data from over 800 respondents from 8 communities selected from across the State of Texas. Section IV describes the implications of using demographic and social factors in projecting water use. The final section, Section V, presents generalizations regarding the overall effects of demographic and social factors on water use and demand ant presents our preliminary recommendations regarding the use of such variables in formulating water use and demand projections. Throughout the report, it should be recognized that the fact that the study is limited to one period of time and to only selected areas of the Stste, clearly limits the ability to formulate generalizations that have statewide applicability. The fact that the study is limited in several regards must be recognized.
Aquatic Life and Habitat Inventory Assessment
(Texas Water Resources Institute, 2007-07) Belzer, Wayne
Traditionally, water quality monitoring has been focused on chemical attributes such as mineral content, metals, and other contaminants. Biological monitoring is becoming more frequently utilized to assess overall ecological integrity of the water body. Biological monitoring is particularly useful in assessing the effects of nonpoint sources of pollution such as nutrient enrichment and sedimentation. Biological monitoring data collected during this project will provide baseline data that will allow comparisons to be made between sites on the Pecos River as well as comparisons to similar rivers in the state. Monitoring efforts will also provide a baseline for sites along the Pecos River. This data can be used to assess trends and future changes that may occur as conditions in the river change. The development of a sustainable Pecos River Basin water management plan would be a giant first step forward and a great aid to maintaining or increasing populations of endangered species found in the Basin. A healthy, natural watershed and riparian zone is critical to life, especially in semi-arid and desert regions. The U.S. Section International Boundary and Water Commission (USIBWC) Clean Rivers Program (CRP) coordinated a biological assessment with assistance from the Texas Commission on Environmental Quality (TCEQ) in the upper Pecos and with the United State Geological Survey (USGS) in the lower Pecos. Sites were selected along the Pecos River in Texas for assessment of biological condition. At those sites, data on benthic macroinvertebrate organisms, fish, and physical habitat characteristics of the river were collected and catalogued according to protocols previously published by the TCEQ.
Aquatic Studies at the Proposed George Parkhouse I Reservoir Site on the South Sulphur River in Northeast Texas
(Texas Water Resources Institute, 2002-12-31) Burgess, Christine C.; Gelwick, Frances P.
In 1997, the Texas Water Development Board identified George Parkhouse I on the South Sulphur River in northeast Texas as a potential reservoir site. This aquatic survey of a future reservoir site is designed to provide information about stream fish upstream and downstream of the proposed dam for instream flow assessment. In addition, this information will be used to identify fish assemblages and habitat associations in unchannelized as well as channelized and diverted waters for consideration of mitigation. Instream flow assessment is habitat oriented to determine the relationship between habitat availability and habitat utilization at different flows within a normal flow regime of the stream. The goals of this study were: 1) map, photograph, and assess habitats, 2) measure ambient water quality parameters, 3) report the abundance of fish of each species collected in each habitat at each of three sample sites upstream (unchannelized reach) and three sample sites downstream (channelized reach) of the proposed reservoir, 4) evaluate the relative health of sites using an Index of Biotic Integrity (Karr et al. 1986) that was regionalized for use in Texas streams (Linam and Kleinsasser 2002), and 5) identify instream habitats based on the relative abundance of fish sampled using an indicator species analysis (Dufrêne and Legendre 1997).
Arsenate and Arsenite Retention and Release in Oxide and Sulfide Dominated Systems
(Texas Water Resources Institute, 1997-06) Wang, Jianlin; Raven, Klaus; Jain, Amita; Loeppert, Richard H.
Metal pollution of surface water resources in Texas is a significant problem, and is caused by the inflow of sediments from oil fields, old mines and industrial sites, and by the discharge of metal contaminated sewage and industrial effluents. In the preliminary phases of this project we were interested in a range of contaminant metals; however, following early experiments it was determined that emphasis would be given to arsenic due to the importance of several arsenic contaminated sites in east and central Texas. Three important general field and laboratory observations have been made concerning arsenic and have served as a basis for these studies: (1) correlations between metal concentrations of suspended solids or sediments (as measured by the recommended EPA and USGS methods) and metal levels in fish are often poor, (2) metal concentrations in pore waters of bottom sediments are often highly variable (with time and space) and often considerably higher (but sometimes lower) than in the overlying water column, (3) arsenic speciation and solubility are strongly influenced by redox potential. Existing EPA and USGS methods for quantifying the arsenic level of sediment or suspended solids primarily involve digestion by strong acids. While these methods do provide an indication of total concentration of metals, they often do not provide a reliable measure of bioavailability, either directly to aqueous animals or indirectly through the food chain. Inorganic arsenic exists primarily in the +3 or +5 oxidation states (depending on redox potential), and its reactions in soils and sediments are influenced by pH, redox potential, dissolved organic or inorganic components, and sediment colloids (especially Fe sulfides and Fe, Mn, and Al oxides and hydroxides) and organic matter. Arsenic is often concentrated at the surfaces of suspended and sediment colloids (as surface adsorbed and occluded species or possibly as poorly ordered solid solutions). Arsenic (+3 and +5) is bound, by ligand bonding mechanisms, at the surfaces of solid phase Fe, Al and Mn oxides, though there are major descrepencies in the literature concerning the relative bonding strengths of arsenate and arsenite. These reactions at colloidal surfaces strongly influence its availability within the biosphere in oxidized systems. Arsenic (+3) is readily precipitated as As2S3 or coprecipitated in the FeS2 or FeS structure, and these compounds often control the solubility of arsenic in low redox environments. Because of these reactions, arsenic is likely strongly influenced by the presence of inorganic sulfur. The objectives of the study were as follows: 1. To characterize the concentrations and chemical forms of arsenic and the factors which influence its retention and release 2. To evaluate the role of the periodic oxidation/reduction processes that may occur in sediments on retention and release of arsenic 3. To evaluate the probable role of biologically induced processes (e.g., oxidation/reduction, acidification, and ligand exchange) which may influence the mobilization of precipitated or adsorbed arsenic 4. To develop surface dissolution procedures to assess heavy metal mobilization potential in sediments in the aquatic environment, with emphasis on calcareous stream bed sediments. The primary benefit of this study will be to improve procedures for assessing the bioavailability and potential biological hazard of metals in suspended solids and sediments. Accomplishment of these objectives has enabled us to recommend procedures for assessing biohazard potential and ultimately to better monitor aquatic environments.
Arsenic in your water?: Economists study perceptions of risks from drinking water high in arsenic
(Texas Water Resources Institute, 2010) Wythe, Kathy
Assembly and Testing of an On-Farm Manure to Energy Conversion BMP for Animal Waste Pollution Control
(Texas Water Resources Institute, 2010-06) Engler, Cady; Capereda, Sergio; Mukhtar, Saqib
Numerous gasification experiments were conducted and proved that with proper moisture content (usually near 10%) animal manure can be gasified using the TAMU fluidized bed gasifier. In summary the following has been established. • The heating value of dairy manure on a dry basis was found to be 15.93 + 0.26 MJ/kg (6,863 + 112 Btu/lb), typical of most agricultural biomass. The heating value was around 14.09 MJ/kg (6,070 Btu/lb), on an “as received” basis (around 13% moisture). • The heating value of synthesis gas from gasification of animal manure was estimated to be around 4.2 MJ/m3 (113 Btu/ft3). This value is very similar to most synthesis gas from agricultural residues. • Synthesis gas production per unit weight of manure was estimated to be 2.11 m3/kg. The gas production energy efficiency was estimated to be around 55.6% (i.e. 55.6% of the energy was contained in the synthesis gas). • Char production was on the average around 20% of the feed input. The average heating value of manure char was around 19 MJ/kg (8,816 Btu/lb). Thus, the char energy conversion efficiency was approximately 24% (i.e. 24% of the energy was still contained in the char). • Twenty percent (20%) of the energy from the biomass was used during the gasification to maintain the temperature of the reactor. Gasification is a continuous, endothermic process and thus, no external fuel is needed other than that used during startup. Natural gas was used during start-up and would last around 30 minutes. After the initial heating of the reactor, part of the biomass materials were used to maintain the operating temperature and the natural gas fuel source was shut off. • The chemical formula for dairy manure during combustion is shown below. This formula was used only for stoichiometric calculation purposes only. • Eutectic point analysis of the manure ash showed that the inorganic ash components will start to melt at around 600°C (1112°F). This was established using compressive strength as an indicator of fusion reactions. • When used for power generation, it was expected to generate at least 25 kW of electrical power output for a 30 cm diameter pilot facility (i.e. at 1.6 tonnes/day (1.8 tons/day)) of feed input. The assumed conversion efficiency was roughly 15% (from synthesis gas to electrical power in a natural gas-type engine-generator).
Assessing Phosphorous Loss to Protect Surface Water
(Texas Water Resources Institute, 2005) Garcia, Raul
Assessment of Stormflow and Water Quality from Undisturbed and Site Prepared Forest Land in East Texas (Final Report)
(Texas Water Resources Institute, 1983-01) Weichert, A. T.; Crawley, W. W.; Nieber, J. L.; Blackburn, W. H.; DeHaven, M. G.
In 1979, nine small forested watersheds were instrumented in East Texas to determine the effect of intensive forest management practices On water quantity and quality. Three replications of three treatments were used: 1) clearcutting - followed by shearing and windrowing, 2) clearcutting - followed by roller chopping and 3) undisturbed control. Following treatment, the sheared and windrowed sites exposed 57% of the surface soil compared to 16% for the chopped watersheds. During 1981, the first year after treatment, stormflow volumes increased with the intensity of the site disturbance. Sites sheared produced the greatest amount of stormflow (5.76 inches), followed by chopped (3.26 inches) and the undisturbed watersheds (1.03 inches). Stormflow volumes decreased 66% and 57% on the sheared and chopped watersheds the second year following treatment. Sediment losses were significantly higher on the sheared watersheds (2,620 lb/acre) than the chopped (22 lb/acre), during 1981. By the fall of 1982, the exposure of mineral soil on the sheared sites dropped to 20% and to 4% on the chopped sites. For this reason and the lower volume of runoff, sediment loss for 1982 dropped to 71.3, 4.9 and 4.5 lb/acre for the sheared, chopped and undisturbed watersheds, respectively. Nitrate concentrations were significantly different between treatments during 1981: Sheared - 205 ppb, chopped - 96 ppb and control 10 ppb. During 1982, although nitrate concentrations were lower, the sheared watershed still had a significantly higher concentration. Total nitrogen concentration on the sheared sites was 2,155 ppb, which was significantly higher than the chopped (999 ppb) or the control sites (996 ppb) for 1981. The first year total nitrogen export from the sheared sites (2.79 lb/acre) was 3.5 times greater than the chopped loss (0.76 lb/acre) and 12 times greater than the loss on the control sites (0.24 lb/acre). The second year following treatment, total nitrogen concentrations were not significantly different and total nitrogen loss on the sheared areas was less than half of the loss recorded from the control sites during 1981. Total phosphorus concentrations for 1981 were 221, 85 and 54 ppb for the sheared, chopped and control watersheds, respectively. Total phosphorus loss for this period was only 0.297 lb/acre from the sheared treatments, but was significantly higher than the chopped or undisturbed treatments. A drop in sediment concentrations and runoff in 1982 reduced phosphorus losses on the sheared watersheds by over 90%. Calcium, potassium and sodium concentrations during 1981, were highest for the chopped treatments, while magnesium concentrations were highest on the sheared treatments. Export of these elements was greatest from the sheared sites, except for calcium, which was lost in greater quantities on the chopped sites. During 1982 there was no significant difference between treatments for Ca, Mg, K and Na concentrations. The rapid revegetation and reduction in exposed mineral soil that occurred on both sheared and chopped treatments during 1982, resulted in a decrease in runoff and sediment and nutrient losses. As the stabilization of sites continues, treatment differences should diminish. Limiting shearing and windrowing activities to the more gentle slopes will reduce first year erosion and prevent increases in sediment and nutrient losses. Roller chopping on the other hand, appears to cause only minor changes to water yield and quality on slopes of up to 25%.
Assessment of Stormflow and Water Quality from Undisturbed and Site Prepared Forest Land in East Texas (Interim Report)
(Texas Water Resources Institute, 1982-01) Weichert, A. T.; Knight, R. W.; Blackburn, W. H.; DeHaven, M. G.
Automation of Pivot Sprinkler Irrigation Systems to More Efficiently Utilize Rainfall and Irrigation Water
(Texas Water Resources Institute, 1980-08) Hutmacher, R. B.; Harbert, H. P. III; Gerst, M. D.; Runkles, J. R.; Wendt, C. W.
A study was conducted to develop automated pivot sprinkler irrigation systems and determine if such systems use less water and energy than manually operated systems. The study was conducted near Earth, Texas, using irrigation systems located on producers farms. Sensors with transmitters and receivers were constructed and tested so that the irrigation systems can be controlled by wind, soil water tension, and rainfall. The sensors can be used separately or in combination to control the irrigation systems. For several reasons it was not possible to determine if automated systems use less water and energy than manually operated systems. The major reason was the low capacity of the wells (114 to 204 m3/hr) supplying the irrigation systems. To meet crop water requirements and losses due to evaporation and runoff, the well capacity should be at least 284 m3/hr. Since the wells could not supply adequate water, soil water tension was out of the tensiometer range for the last 60 days of the growing season. Considerable variation in soil water tension and content was noted between irrigation systems and within quadrants of each irrigation system. Systems planted to cotton would probably be easier to automate than those planted in corn because of the lower water requirements of cotton. The wind and rainfall controls have more promise to aid in increasing water use efficiency than controls activated by soil water sensors. Wind controls could be used during preirrigation when more time is available to apply water and rainfall controls could be an aid to producers with remotely located irrigation systems.
Bacteria Runoff BMPs for Intensive Beef Cattle Operations
(Texas Water Resources Institute, 2010-12) Wagner, Kevin; Redmon, Larry; Gentry, Terry
According to the 2008 Water Quality Inventory and 303(d) List, 291 of the 516 impairments (i.e. 56%) were the result of excessive bacteria. Modeling and bacteria source tracking has identified grazing cattle as a source of this bacterial contamination. To help address this, the Natural Resources Conservation Service (NRCS) funded this project to evaluate the effect of stocking rate on pathogen transport from beef cattle operations and develop guidance for landowners on restoring water quality. The project included three tasks: (1) Project Coordination and Administration, (2) Assess Bacteria Runoff from Intensively Managed Beef Cattle Operations, and (3) Technical Transfer. Task 1, Project Coordination and Administration, consisted of the Texas Water Resources Institute (TWRI) preparing and submitting eleven quarterly progress reports and the final project report, holding 25 coordination meetings, and submitting 12 invoices. To evaluate the impact of grazing management on bacterial runoff (Task 2), TWRI and Texas AgriLife Extension Service (AgriLife Extension) installed three 1-hectare watershed sites at the Texas A&M University Beef Cattle Systems Center (BCSC), located near College Station. Sites were bermed and equipped with 90o v-notch weirs, ISCO® samplers with bubble flow meters, and a rain gage. TWRI and AgriLife Extension maintained these watershed sites for two years, conducting over 30 site visits. A variety of stocking rates were evaluated. Site BB1 was ungrazed. Site BB2 was stocked at typical stocking rates (SR) for the area (i.e., 3-4 acres per animal unit [AU]). Site BB3 was stocked at a rate twice that of site BB2. Over the course of the project, six grazing treatments were conducted at sites BB2 and BB3. From November 2008 through October 2010, TWRI and AgriLife Extension assessed bacterial concentrations and runoff volume from the watershed sites. E. coli concentrations at all sites greatly exceeded Texas Water Quality Standards. Even at the ungrazed site, non-domesticated animals (i.e., feral hogs) and wildlife significantly impacted E. coli levels preventing attainment of water quality standards, thus indicating the difficulty in achieving standards during runoff events due to background loadings. Data also indicated moderate stocking does not significantly increase E. coli levels above background levels and suggests that 67-85% reductions in E. coli levels may be achieved by converting from heavy to moderate stocking rates. It was also found that pastures stocked heavier than 10 acres per AU should be the primary focus of implementation efforts in this and similar environments. Our data indicated (1) stocking at rates heavier than 10 acres per AU (as is much of the improved pastureland in Texas) may increase E. coli concentrations in runoff while (2) stocking at rates less than 10 acres per AU (much of the rangeland in Texas) does not yield higher E. coli levels than ungrazed pastures. Finally, data show that runoff events occurring while the sites were stocked or within two weeks of them being stocked produced the highest E. coli concentrations; thus, it is recommended grazing in creek pastures be deferred during rainy periods. Within two weeks of grazing, E. coli levels had fallen substantially and after 30 days, E. coli values had declined to background levels. The findings and recommendations regarding appropriate stocking rates/grazing management to minimize bacterial runoff into surface waters of Texas are being included in a fact sheet, presentation, and other resources that will become part of the Lone Star Healthy Streams Beef Cattle Resource Manual. Throughout this project a series of educational programs conducted through the Lone Star Healthy Streams Program transferred information regarding bacterial runoff and conservation practices for reducing it to livestock producers at over 60 programs around the state. Additionally, the website reached 1,038 unique visitors since its inception. These programs have increased awareness of bacterial runoff from beef cattle grazing operations and conservation practices designed to reduce bacterial loading to Texas streams and water ways. Much work remains to be done. The applicability of water quality standards during runoff events should be evaluated in light of the findings of this study; more data is needed to evaluate the impact of stocked pastures on bacterial runoff; work is needed to assess the impacts of continuous grazing on E. coli runoff; and transfer of this information to cattlemen throughout Texas must continue.
Bacteria TMDL Projects
(Texas Water Resources Institute, 2007) Wythe, Kathy

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