USGS Science⌕ Search

Geology topics

Research about Texas

Source-linked reports with geographic coverage including Texas.

At least 973 records · Page 54Linked to original sources
USGS1987

Hydrologic data for urban studies in the Austin metropolitan area, Texas, 1985

Hydrologic investigations of urban watersheds in Texas were begun by the U.S. Geological Survey in 1954. Studies are now in progress in Austin, and Houston. Studies have been completed in the Dallas, Fort Worth, and San Antonio areas. The Geological Survey, in cooperation with the Texas Department of Water Reources, began hydrologic studies in the Austin urban area in 1954. In cooperation with the city of Austin, the program was expanded in 1975 to include additional streamflow and rainfall gaging stations, and the collection of surface water-quality data. In 1978, the program was expanded to include a ground-water resources study of the South Austin metropolitan area in the Balcones Fault Zone. The objectives of the Austin urban hydrology study are as follows: To determine, on the basis of historical data and hydrologic analyses, the magnitude and frequency of flood peaks and flood volume. To determine the effect of urban development on flood peaks and volume. To determine the variations in water quality during different seasons and flow conditions in representative watersheds with various types of urban development. To quantitatively appraise the ground-water resources of the Edwards aquifer in hydraulic circulation with Barton Springs, the effect of urbanization on the quality and quantity of recharge and discharge, and the extent of contamination in the aquifer. This report presents the basic hydrologic data collected in the Austin urban area for the 1985 water year (Oct. 1, 1984 to Sept. 30, 1985). Additional explanations of terms related to streamflow, water quality, and other hydrologic data used in this report are defined in the U.S. Geological Survey annual report Water Resources Data for Texas, TX-85-3, 1985.

Texas↗
USGS1987

Records of wells, drillers' logs, water-level measurements, and chemical analyses of ground water in Harris and Galveston Counties, Texas, 1980-84

Information on major new water wells in Harris and Galveston Counties was compiled by the U.S. Geological Survey from 1980 to 1984. This report presents the results of the hydro!ogic data collection on new large-capacity and other selected wells, including well location and completion data, drillers 1 logs of the strata penetrated, water levels, and chemical quality of the produced water. These water-well data are supplementary to similar data on older wells in these counties and to descriptive evaluations of the ground-water resources which have been published previously.

Texas↗
USGS1987

Index of surface-water stations in Texas, January 1987

As of January 1, 1987, the surface-water data-collection network in Texas included 376 continuous streamflow, 76 continuous or daily reservoir-content, 34 gage height, 16 crest-stage partial-record, 8 periodic discharge through range, 33 floodhydrograph partial-record, 9 flood-profile partial-record, 36 low-flow partial-record, 46 daily chemical-quality, 19 continuous-recording water-quality, 84 periodic biological, 17 lake surveys, 162 periodic organic and (or) nutrient, 3 periodic insecticide, 42 periodic pesticide, 19 automatic sampler, 141 periodic minor elements, 130 periodic chemical-quality, 78 periodic physical-organic, 22 continuous-recording three- or four-parameter water-quality, 34 periodic sediment, 22 continuous-recording temperature, and 30 national stream-quality accounting network stations. Plate 1 shows the location of surface-water streamflow or reservoir-content and chemical-quality or sediment'stations in Texas. Plate 2 shows the location of partial-record surfacewater stations. This index shows the station number and name, latitude and longitude, type of data collected, and the office principally responsible for the data collection (table 1). An 8-digit permanent numerical designation for gaging stations has been adopted on a nationwide basis; stations are numbered and listed in downstream order. In the downstream direction along the main stem, all stations on a tributary entering above a main-stem station are listed before that station. A tributary entering between two main-stem stations is listed between them. A similar order is followed in listing stations on first rank, second rank, and other ranks of tributaries. To indicate the rank of any tributary on which a gaging station is situated and the stream to which it is an immediate tributary, each indention in the listing of gaging stations represent one rank. This downstream order and system of indention show which gaging stations are on tributaries between any two stations on a main stem and the rank of the tributary on which each gaging station is situated. On plates 1 and 2, the 8-digit station number is abbreviated because of space limitation.

Texas↗
USGS1987

Texas ground-water quality

This report contains summary information on ground-water quality in one of the 50 States, Puerto Rico, the Virgin Islands, or the Trust Territories of the Pacific Islands, Saipan, Guam, and American Samoa. The material is extracted from the manuscript of the 1986 National Water Summary, and with the exception of the illustrations, which will be reproduced in multi-color in the 1986 National Water Summary, the format and content of this report is identical to the State ground-water-quality descriptions to be published in the 1986 National Water Summary. Release of this information before formal publication in the 1986 National Water Summary permits the earliest access by the public.

Texas↗
USGS1987

Floods in central Texas, August 1-4, 1978

Catastrophic floods caused by record rainfall occurred in central Texas during August 1-4, 1978. Torrential rain initiated by the remnants of tropical storm Amelia fell over south-central Texas during August 1-3, and very intense rain due to the interaction between the cold front and maritime air mass fell over north-central Texas on August 3-4. Rainfall of more than 48 inches near Medina in south-central Texas established a new United States record of extreme point rainfall for a 72-hour period. Major flooding occurred on the Medina and Guadalupe Rivers. Severe to minor flooding occurred on the Brazos, Llano, Pedernales, and Nueces Rivers. Floods with recurrence intervals in excess of 100 years and recordsetting peak discharges were observed at several streamflow stations. Thirty three lives were lost and total damages reportedly exceeded $110 million.

Texas↗
USGS1987

Water resources data, Texas, water year 1986, Volume 1: Arkansas River basin, Red River basin, Sabine River basin, Neches River basin, Trinity River basin, and intervening and adjacent coastal basins

The Water Resources Division of the U.S. Geological Survey, in cooperation with Federal, State, and City agencies, obtains a large amount of data pertaining to the water resources of Texas each water year. Such data, accumulated during many water years, constitute a valuable data base for developing an improved understanding of the water resources of the State. To make these data readily available to interested parties outside the Geological Survey, the data are published annually in three volumes of this report series entitled "Water Resources Data - Texas." This report series includes records of stage, discharge, and water quality of streams and canals; stage, contents, and water quality of lakes and reservoirs. Volume 1 contains records for water discharge at 139 gaging stations; stage only at 5 gaging station; stage and contents at 40 lakes and reservoirs; and water quality at 72 gaging stations. Also included are data for 13 partial-record stations. Additional water data were collected at 2 miscellaneous sites not involved in the systematic data-collection program. The data in this report represent that part of the National Water Data System collected by the U.S. Geological Survey and cooperating City, State, and Federal agencies in Texas.

Texas↗
USGS1987

Water resources data, Texas, water year 1986. Volume 2: San Jacinto River basin, Brazos River basin, San Bernard River basin, and intervening coastal basins

The Water Resources Division of the U.S. Geological Survey, in cooperation with Federal, State, and City agencies, obtains a large amount of data pertaining to the water resources of Texas each water year. Such data, accumulated during many water years, constitute a valuable data base for developing an improved understanding of the water resources of the State. To make these data readily available to interested parties outside the Geological Survey, the data are published annually in three volumes of this report series entitled "Water Resources Data - Texas." This report series includes records of stage, discharge, and water quality of streams and canals; stage, contents, and water quality of lakes and reservoirs. Volume 2 contains records for water discharge at 112 gaging stations; stage only at 9 gaging station; stage and contents at 24 lakes and reservoirs; and water quality at 72 gaging stations. Also included are data for 39 partial-record stations. The data in this report represent that part of the National Water Data System collected by the U.S. Geological Survey and cooperating State and Federal agencies in Texas.

Texas↗
USGS1987

Effects on water quality due to flood-water detention by Barker and Addicks Reservoirs, Houston, Texas

The Barker and Addicks Reservoirs, located about 16 miles west of Houston, Texas, provide flood-detention storage for storm runoff. Of interest are the water-quality characteristics in the study area and changes in water quality during detention. Study area sampling sites were selected upstream along Buffalo Bayou for Barker Reservoir and on Bear Creek and Langham Creek for Addicks Reservoir, within the reservoirs, near the reservoir outflows, and below the confluence of each reservoir outflow at the streamflow station Buffalo Bayou near Addicks. Flow data were available at all sites except in the reservoirs. Analyses of samples collected during both low flow and storm runoff show that, in general, the waters of the study area were low in mineralization, but the aesthetics of the water was a problem. The inorganic constituents, trace metals, and pesticides rarely exceeded maximum contaminant levels recommended by the U.S. Environmental Protection Agency for public supply using 1976 and 1977 criteria for primary and secondary standards. All species of nutrients, except ammonia nitrogen and phosphorus, almost always were below the recommended maximum contaminant levels. Phosphorus almost always exceeded these levels. Aesthetic problems are evident. Large values of suspended solids, turbidity, and color were common. Small dissolved-oxygen values commonly occurred in the reservoirs. Possible bacterial problems are indicated because coliformbacteria densities exceeded recommended levels in about 25 percent of the samples. The effects of the reservoirs on the water-quality characteristics of storm runoff were analyzed using three approaches. The first approach was a comparison of the discharge-weighted average values of nine selected constituents at each streamflow-gaging station during four storms. Reservoir effects on the quality of runoff detained 1 to 4 days in the two reservoirs were inconsistent. However, the reservoirs consistently had an effect on the water quality of runoff that was detained the longest (more than 8 days). Biochemical oxygen demand, suspended solids, turbidity, color, total nitrogen, and total organic carbon discharge-weighted average values were consistently smaller after flowing through the reservoirs. Dissolved solids and total phosphorus values were consistently larger after flowing through the reservoirs. The second approach was an analysis of the means of the discharge-weighted average values computed for the four hydrologic events using the Student t-test. Statistical results Indicate that reservoir detention significantly reduced suspended solids (the mean decreased from 178 milligrams per liter at the Inflows to 105 milligrams per liter at the outflows) and turbidity (the mean decreased from 119 nephelometrlc turbidity units at the inflows to 66 nephelometric turbidity units at the outflows). The third approach was a comparison at each site of the mean, maximum, and minimum values computed for seven constituents that did not correlate with discharge. These constituents or properties of water were temperature, pH, dissolved oxygen, dissolved oxygen percent saturation, total-coliform bacteria, fecal-conform bacteria, and fecal-streptococci bacteria. The only consistent water-quality changes observed were with the three bacteria groups, which were decreased by flood-water detention.

Texas↗
USGS1987

Effects of runoff controls on the quantity and quality of urban runoff at two locations in Austin, Texas

Rapid urban development in the Austin metropolitan area, Texas, is causing concern about increasing peak discharges from storm runoff and the degradation of the quality of water in receiving streams, lakes, and aquifers. In an attempt to decrease peak discharges and improve water quality, runoff controls are being required in some watersheds. This report summarizes the precipitation, streamflow, and water-quality data collected from September 1982 to September 1984 upstream and downstream from runoff controls at two locations, and presents the effects of these runoff controls on streamflow and the quality of runoff water. The two controls are a detention and filtering pond near Barton Creek Square Shopping Center, a large shopping center southwest of downtown Austin, and a grass-swale control in the Al ta Vista Planned Unit Development, a multipie-family housing area. At Barton Creek Square Shopping Center, rainfall for the storms analyzed ranged from 0.14 to 2.88 inches. The rainfall rate for the September 7, 1983, storm exceeded the 100-year return period for the 5- and 10-minute duration and was equal to the 50-year return period for the 15-minute duration. Peak discharge at the inflow station to the detention pond was closely related to the maximum rainfall during a 5-minute period and occurred about 10 minutes later. The maximum inflow at this station was 185 cubic feet per second and appeared to be the limit of the storm sewer system. For small- and moderate-sized storms, the runoff is contained in the detention pond and passes through a filter system. Runoff from large storms overflows into the drop outlet. For storms contained in the pond, peak discharges at the outflow station generally were less than 3.1 cubic feet per second. As time passed, the outflow peak discharges tended to decrease as a result of reduced permeability of the filter. Cleaning the filter appeared to increase the peak flows but did not restore them to the previous level. The runoff-rainfall ratio averaged 0.85 at the inflow station and 0.36 at the outflow station. A water budget shows unexplained losses to average 20 percent. At the Barton Creek Square Shopping Center, discharge-weighted densities of fecal-col iform and fecal-streptococci bacteria and discharge-weighted concentrations of biochemical oxygen demand, chemical oxygen demand, total organic carbon, suspended solids, total ammonia plus organic nitrogen, and total phosphorus generally were larger in the inflow than in the outflow. Discharge-weighted concentrations of dissolved lead, dissolved iron, and dissolved zinc generally were small in both the inflow and outflow; however, the larger discharge-weighted concentrations of these constituents generally were found in the inflow. Discharge-weighted concentrations of volatile dissolved solids were smaller in the inflow than in the outflow for 10 of the 22 storms analyzed. Discharge-weighted concentrations of total nitrite plus nitrate nitrogen and dissolved solids generally were much smaller in the inflow than in the outflow. It is likely that organic and ammonia nitrogen trapped in the pond from previous storms and in the inflow water as it flows through the pond is being oxidized to nitrite and nitrate nitrogen. Similarly, dissolved solids retained in the filter or on the bed of the pond from previous storms are being leached to the outflow. Measured peak concentrations or densities of most constituents in the inflow were significantly larger than those in the outflow for most constituents. An exception was noted for concentrations of total nitrite plus nitrate which were larger in the outflow than the inflow as indicated by discrete sample analysis for six storms. Loads of most constituents and total numbers of bacteria were significantly larger in the inflow than in the outflow. The total numbers of bacteria were reduced by approximately 80 percent. Average removal efficiencies for suspended solids, biochemical oxygen demand, total phosphorus, total organic carbon, chemical oxygen demand, and dissolved zinc ranged between 60 and 80 percent. The average loads of dissolved solids were approximately 13 percent larger in the outflow than the inflow. Average loads of total nitrite plus nitrate nitrogen were approximately 110 percent larger in the outflow than in the inflow. The increase in loads of these constituents is due to material being leached from the bed of the pond or from the filter system. At Al ta Vista, rainfall for the storms analyzed ranged from 0.25 to 2.00 inches. The maximum rainfall intensity was 0.30 inch for a 5-minute interval. The runoff-rainfall ratio averaged 0.42 and appeared to be evenly distributed about the mean ratio line. The peak discharge at the inflow station to the grass-covered swale area was 0.93 cubic foot per second. Inaccuracies of discharge at the outflow station and variations in the ungaged drainage area with the size of the storm prevented a hydrologic analysis of the basin above this station. Discharge-weighted concentrations of total phosphorus were larger in the outflow than in the inflow for each of the 19 storms analyzed. Discharge-weighted concentrations of dissolved solids, volatile dissolved solids, biochemical oxygen demand, chemical oxygen demand, and total organic carbon were larger in the outflow than in the inflow for at least 12 of the 19 storms analyzed. Discharge-weighted densities of fecal streptococci were decreased between the inflow and outflow, with discharge-weighted densities of fecal streptococci being less in the outflow for 15 of the 19 storms analyzed. Because of the relatively small variations in concentrations and densities of constituents between the inflow and outflow sites, and because of the errors in discharge at the outflow gage, it is not feasible to determine the effect of the grass-covered swales on discharge-weighted concentrations and densities of water-quality constituents. Discrete concentrations or densities of most constituents were not decreased. Peak concentrations of dissolved solids in the outflow exceeded peak concentrations in the inflow for all five of the storms analyzed with discrete samples. Peak concentrations of suspended solids, total ammonia plus organic nitrogen, total nitrite plus nitrate nitrogen, total nitrogen, and dissolved iron were larger in the outflow than in the inflow for four of the five storms analyzed. Load-removal efficiencies of water-quality constituents could not be determined because of inaccuracies in measuring discharge at the outflow site,

Texas↗
USGS1987

Comparison of irrigation pumpage and change in water storage of the High Plains Aquifer in Castro and Parmer counties, Texas, 1975-83

An understanding of the relationship between irrigation pumpage and change in ground-water storage was needed to quantify the amount of water returning to the High Plains aquifer as a result of intensive irrigation in Castro and Parmer Counties, Texas. Irrigation pumpage for the 9-year period, 1975-83, was estimated by using the Blaney-Criddle consumptive-use formula adjusted by a factor to account for irrigation demand and field-measured crop applications. Total estimated pumpage for the 9-year period was 11,269,000 acre-feet and 8,914,000 acre-feet. The estimated pumpage was based upon reported crop acreage data and LANDSAT acreage data, respectively. Aquifer storage for the same period was estimated as the product of specific yield, net water-level change, and area. Change in storage was 5,168,000 acre-feet. Many of the areas of the largest change in storage also were the areas of the largest saturated thickness. The only locations that did not experience substantial water-level declines were the northwest and northeast parts of the study area. A comparison was made of water returning to the aquifer by calculating the difference between irrigation pumpage and the change in aquifer storage. Two estimates of this comparison, expressed as a percentage of irrigation pumpage, were obtained on the basis of two different sources of acreage data. This comparison was 54 percent of pumpage based on reported crop acreage data and 42 percent of pumpage based on LANDSAT interpreted acreage data.

Texas↗
USGS1987

Ground-water withdrawals and changes in ground-water levels, ground-water quality, and land-surface subsidence in the Houston district, Texas, 1980-84

During 1980-84, ground-water withdrawals from the Chicot and Evangeline aquifers in the Houston district decreased from 511 million gallons per day to 444 million gallons per day. This 13-percent decrease was due to the increased availability of surface water and a decreased demand for water. The largest decreases in ground-water withdrawals occurred in the Houston area. Ground-water pumpage was 219.2 million gallons per day during 1984 compared to 254.8 million gallons per day during 1980. Decreases in ground-water withdrawals from 1980 through 1984 occurred in most of the other areas in the Houston district (Pasadena, Katy, Baytown-LaPorte, and Texas City). Large decreases in ground-water withdrawals for rice irrigation in the Katy area were offset by increases in ground-water withdrawals for public supply. Hence, in the Katy area, the quantity of ground water withdrawn during 1984, 148.9 million gallons per day, was only slightly less than the 157.5 million gallons per day withdrawn during 1980. Water levels generally rose in the eastern part of the Houston district and declined in the western part from spring 1980 to spring 1985. The rise of water levels in wells in the Chicot and Evangeline aquifers was as much as 80 feet and 60 feet, respectively. The decline of water levels in wells in the Chicot and Evangeline aquifers was as much as 40 feet and 80 feet, respectively. Slight decreases in chloride concentrations in water from the Chicot aquifer occurred in the Alta Loma area between 1980 and 1984. In 1980, chloride concentrations in water from the Chicot aquifer ranged from 250 to 790 milligrams per liter, whereas in 1984, chloride concentrations ranged from 180 to 710 milligrams per liter. Water from one well in the Texas City area had an increase in chloride concentrations from 265 milligrams per liter in 1980 to 300 milligrams per liter in 1984. In water from another well in the Texas City area, chloride concentrations decreased from 760 milligrams per liter in 1980 to 710 milligrams per liter in 1984. The concentrations of chloride and dissolved solids in water from the Evangeline aquifer remained less than 100 milligrams per liter and 500 milligrams per liter during 1980-84. Land-surface subsidence is still evident in the Houston district. Subsidence rates between 1980 and early 1985 in the eastern and southeastern parts of the Houston district were less than during 1975-79. At the Seabrook site, where a monitor measures most of the subsidence, the average compaction rate during 1980 to early 1985 was 0.04 foot per year while during 1975-79, the rate was 0.14 foot per year. However, subsidence rates in the western, southwestern, and northern parts of the Houston district during 1980 to early 1985 increased from the 1975-79 rates. At the Addicks site, the land surface has subsided at a rate of about 0.17 foot per year from 1980 to early 1985. The subsidence rate from 1975 through 1979 at the site was 0.11 foot per year.

Texas↗
USGS1987

Water quality of Cedar Creek reservoir in northeast Texas, 1977 to 1984

Water in Cedar Creek Reservoir in northeast Texas had volume-weighted average concentrations of less than 140 milligrams per liter of dissolved solids, less than 30 milligrams per liter of dissolved sulfate, and less than 25 milligrams per liter of chloride between vh nuary 1977 and August 1984. The water was soft to moderately hard; the total hardness concentrations ranged from 55 to 75 milligrams per liter as calcium carbonate. Thermal stratification in Cedar Creek Reservoir usually begins in late winter or early spring and persists until late fall. Stratification or summer stagnation causes significant seasonal and areal variations in concentrations of dissolved oxygen, iron, manganese, total inorganic nitrogen, and total phosphorus. Oxygen used in the decay of organic matter is not replenished during summer stagnation, and water below depths of 30 feet usually contains less than 2 milligrams per liter of dissolved oxygen. Often, oxygen is nearly depleted near the bottom in the deepest areas of the reservoir, thus causing reducing conditions. Reducing conditions during summer stagnation result in the dissolution of iron and manganese in bottom sediments. At the deepest site (Ac) near Joe B. Hoggset Dam, dissolved iron concentrations in water near the bottom averaged 1,860 micrograms per liter and manganese concentrations averaged 3,170 micrograms per liter. The concentrations of dissolved iron and dissolved manganese averaged less than 120 micrograms per liter throughout the reservoir during winter and spring circulation and in water near the reservoir's surface during summer stagnation. Seasonal temperature and dissolved oxygen cycles cause the recycling of dissolved iron and manganese between the water and bottom sediments. However, no substantial accumulation of these constituents within the reservoir was detected during the study. Of 10 trace elements studied, barium and arsenic were the most commonly found in detectable concentrations. Of 22 water samples collected for traceelement analysis, 15 contained barium in concentrations ranging from 40 to 300 micrograms per liter, and 19 contained arsenic in concentrations ranging from 1 to 26 micrograms per liter. However, these concentrations are below the maximum contaminant Hmit for barium (1,000 micrograms per liter) and arsenic (50 micrograms per liter) in drinking water. The concentrations of total inorganic nitrogen, total nitrogen, and total phosphorus were largest during summer stagnation in water near the bottom at the deepest sites. At site Ac, the largest total phosphorus concentration was 5.3 milligrams per liter for a bottom sample. The maximum total inorganic nitrogen concentration for the same sample was 2.5 milligrams per liter. Water near the surface of Cedar Creek Reservoir during summer stagnation and throughout the reservoir during winter circulation had total phosphorus and total inorganic nitrogen concentrations of less than 0.1 milligram per liter. Total nitrogen concentrations near the surface ranged from 0.3 to 1.1 milligrams per liter from January 1980 to August 1984.

Texas↗
USGS1987

Organochlorine contaminants and reproductive success of black skimmers in south Texas, 1984

Ninety-four Black Skimmer ( Rhynchops niger ) nests on a dredged-material island colony near Laguna Vista, Texas, were fenced and monitored in 1984 from early incubation until 21 d after the last egg hatched. The daily probability of success was greater during the nestling (99.7%/d/nest) period than during the incubation (98.5%) or hatching (98.5%) periods. By contrast, the success of eggs or young in successful nests was greater during the incubation (91.3%) and hatching (84.3%) periods than the nestling period (63.8%). An estimated 1.1 young/nest survived to 21 d of age. DDE concentrations in eggs were lower in 1984 than in eggs from the same colony in 1979-1981. DDE was higher in eggs taken from nests where none of the remaining eggs hatched (x̄ = 5.9 ppm) compared to eggs taken from nests where all the remaining eggs hatched (x̄ = 1.9 ppm).

Texas↗
USGS1986

Population trends, reproductive success, and organochlorine chemical contaminants in waterbirds nesting in Galveston Bay, Texas

The effects of environmental contaminants on the reproductive success of olivaceous cormorants ( Phalacrocorax olivaceus ), laughing gulls ( Larus atricilla ), and black skimmers ( Rhynchops niger ) nesting in Galveston Bay, Texas were investigated from 1980 through 1982. Populations of cormorants and gulls have remained stable in recent years, but skimmer numbers may have declined. Cormorants produced 1.9 to 2.8 young per pair in nests that remained active throughout the season. Gull and skimmer reproduction was seriously limited by storms and predation. DDE and polychlorinated biphenyl (PCB) residues in carcasses and eggs generally were below levels associated with chronic poisoning and reproductive problems in most species of birds. Possible exceptions were four black skimmer carcasses with DDE concentrations that ranged from 20 to 92 Μ g/g and one olivaceous cormorant carcass with 20 Μ g/g DDE. The generally low levels of dieldrin, chlordane, HCB, toxaphene, and heptachlor epoxide were below those know to affect avian reproduction and survival. Mean DDE residues in cormorant and gull eggs were less than 1.8 Μ g/g. The mean DDE residue in skimmer eggs was less than 3.3 Μ g/g; 12% of the skimmer eggs contained at least 12 Μ g/g DDE, a level known to cause reproductive problems in some avian species. DDE in the eggs of all species declined from 1.5- to 7-fold over the past decade. Polychlorinated biphenyl was detected in all gull and skimmer eggs and in 90% of the cormorant eggs. Residues of PCB in cormorant and skimmer eggs in 1980–82 were lower than in 1970, but the frequency of occurrence in gull eggs increased. Polychlorinated styrenes were recovered in 45% of the cormorant carcasses at levels below 1 Μ g/g. Eggshell thicknesses in all three species were similar to those of eggshells collected before the widespread use of DDT.

Texas↗
USGS1986

Trace metal seasonal variations in Texas marine sediments

Trace elements in coastal environments are derived from three major sources: (1) the bordering watershed; (2) the offshore marine environment; and (3) industrial and/or urban effluent. The site of deposition, however, is controlled by physical and chemical processes in the coastal zone. In many cases, these processes are controlled by climate and can vary seasonally. In the harbor at Corpus Christi, Texas, the summer climate creates an oxygen-poor environment in the water column near the sediment-water interface. This causes chalcophilic metals to precipitate from the water, resulting in high concentrations in the sediments near the source. During the winter, turbulence created by strong winds causes the entire water mass to become aerated and oxidizing, and remobilization of some metals results. In addition, this turbulence accelerates circulation which transports the metal-enriched waters from the harbor. On the outer continental shelf of south Texas, the infaunal activity varies seasonally with bottom water temperatures. As this infaunal activity has an effect on the chemical environment within the sediment near the sediment-water interface, the observed trace metal content at the interface also appears to change with the seasons.

Texas↗
USGS1986

Hatching success of Caspian terns nesting in the lower Laguna Madre, Texas, USA

The average clutch size of Caspian Terns nesting in a colony in the Lower Laguna Madre near Laguna Vista, Texas, USA in 1984 was 1.9 eggs per nest. Using the Mayfield method for calculating success, one egg hatched in 84.1% of the nests and 69.8% of the eggs laid hatched. These hatching estimates are as high or higher than estimates from colonies in other areas.

Texas↗