Geology topics

H.B. Mendieta

Publications and source records attributed to H.B. Mendieta.

3 recordsLinked to original sources

USGS1983

Water quality of Somerville Lake, south-central Texas

Somerville Lake in south-central Texas is a shallow lake, with a mean depth of 14 feet. The maximum depth of the submerged channel of Yegua Creek is usually less than 35 feet and in most areas of the lake the depth is less than 10 feet. Several factors including thermal circulation resulting from the cooling of surface water, wind action, and the large inflow volume in realtion to the lake volume combine to keep the lake well mixed throughout the year. The oxygen concentrations remain high areally and at depth because of good circulation of lake waters during most of the year. Even in summer most bottom oxygen concentrations were in excess of 50 percent of saturation. Due to year-round high percent oxygen saturation from surface to bottom in most parts of the lake, caused by the frequent periods of circulation that occur during all seasons, concentrations of dissolved iron, and manganese reamin low. Dissovled iron concentrations were less than 50 micrograms per liter and dissolved manganese concentrations were less than 40 micrograms per liter. The total inorganic nitrogen concentrations varied little throughout the lake. During the summer, concentrations were 0.01 milligram per liter at the surface to 0.02 milligram per liter at the bottom; and during the winter 0.11 milligram per liter at the surface and 0.10 milligram per liter at the bottom. Concentrations in the headwaters were about double those in the lake. Surface and bottom total phosphorus concentrations, during summer and winter averaged about the same, 0.04 and 0.06 milligram per liter throughout the lake, except in the headwaters where the concentrations were about double those in the lake. Homogeneous or near homogeneous concentrations of total phosphorus and inorganic nitrogen can occur at any time of the year throughout the lake. Total phosphorus concentrations did not increase during the year or during the study period. On the other hand total inorganic nitrogen concentrations did show an annual cycle and were highest in the spring and lowest in late summer or fall. During periods of large releases of water, the more soluble total inorganic nitrogen was flushed from the lake. The concentration of dissolved solids ranged from 139 to 292 milligrams per liter and averaged about 220 milligrams per liter. Dissolved chloride concentrations ranged from 20 to 68 milligrams per liter and averaged 43 milligrams per liter. Dissolved sulfate concentrations ranged from 30 to 130 milligrams per liter and averaged 63 milligrams per liter. The total hardness of the water ranged from 75 to 140 milligrams per liter, expressed as calcium carbonate, placing it in the moderately hard to hard (61 to 180 milligrams per liter) classification. The concentrations of principal dissolved constituents indicate that Somerville Lake is an excellent source of water for municipal, industrial, or agricultural use.

Water-Resources Investigations Report↗

USGS1982

Water quality of Belton Lake, central Texas

The concentrations of dissolved solids, chloride, and sulfate in Belton Lake on the Leon River in central Texas average about 240 milligrams per liter, 40 milligrams per liter, and 30 milligrams per liter, respectively. The water is hard or very hard, averaging 170 milligrams per liter as calcium carbonate. The average concentrations of these constituents and hardness are least during late summer and early fall after periods of sustained high inflow. Thermal stratification begins to develop in Belton Lake in late February or early March. The water usually is stratified into three fairly distinct layers by early June, and stratification usually persists until September or October. Thermal stratification and seasonal variations in the concentrations of dissolved constituents in inflow result in stratification of the principal dissolved constituents. Dissolved solids in water at the surface of deep sites during summer differ from those at the bottom by about 40 milligrams per liter. Thermal stratification also results in significant seasonal and areal variations in dissolved oxygen, dissolved iron, dissolved manganese, total inorganic nitrogen, and total phosphorus. Oxygen used in the oxidation of dead organisms and other organic material near the bottom of the lake is not replaced during periods of summer stagnation. Consequently, water below depths of 35 to 40 feet (10.7 to 12.2 meters) usually contains less than 1.0 milligram per liter of dissolved oxygen during these periods. Water near the surface at most sites in the lake throughout the year usually contains less than 30 micrograms per liter of dissolved iron and 20 micrograms per liter of dissolved manganese. Reducing conditions during periods of summer stagnation result in tile dissolution of iron and manganese from the sediments in deep areas of the lake. The concentrations of both constituents are greatest near the bottom at site Ac, a deep site near Belton Dam. Iron concentrations at this site during the summer have ranged from 0 to 600 micrograms per liter and have averaged about 290 micrograms per liter; manganese concentrations have ranged from 0 to 540 micrograms per liter and have averaged about 320 micrograms per liter. Concentrations of total inorganic nitrogen and total phosphorus are greatest at deep sites during periods of summer stagnation when decay of aquatic organisms and chemical reduction of bottom sediments release the constituents to the water. The concentrations of total inorganic nitrogen and total phosphorus in the bottom stratum of water at site A c during the summer average about 0.75 milligram per liter of nitrogen and 0.10 milligram per liter of phosphorus. The concentrations of these constituents in the surface stratum at site A C during the summer average about 0.02 milligram per liter of nitrogen and 0.01 milligram per liter of phosphorus. The maximum concentrations of chlorinated hydrocarbon insecticides or their degradation products detected in bottom sediments collected from the lake during four lake surveys included 1.1 micrograms per kilogram of DDT, 3.0 micrograms per kilogram of DDD, 11 micrograms per kilogram of DDE, and 2 micrograms per kilogram of chlordane.

Open-File Report↗

USGS1964

Chemical quality of surface waters in the Brazos River basin in Texas

The Brazos River basin, which makes up 15 percent of the land area of Texas, extends from the High Plains, where altitudes reach 4,200 feet and the average precipitation ranges from 15 to 20 inches a year, to the Gulf of Mexico where the annual rainfall is 45-^50 inches. Large reservoirs have been built in the Brazos River basin, but the use of the stored water has been limited because the salinity often makes the water undesirable for municipal and industrial use. However, the water is generally satisfactory for irrigation. Records for the Brazos River show that the salinity of the water was a problem even as early as 1906 and that the water more often than not failed to meet today's chemical-quality standards for a municipal supply. The salt load of the Brazos River comes from the entire basin and is the result of solution, accretion of undetermined amounts of oil-field brine, and accretion of brine from springs and seeps such as those in Salt Croton Creek which contribute about 400 tons of chloride a day. Much of the salinity of the Brazos River is due to inflow of brines above Possum Kingdom Dam. The area above Possum Kingdom Dam is about 52 percent of the total area in the Brazos River basin but contributes only about 17 percent of the total runoff; however, about 50 percent of the annual salt load comes from this part of the basin. Quality-of-water records show a wide difference in the salinity of the steams in different parts of the basin, Dissolved-solids concentrations ranged from about 100 ppm (parts per million) for flood water to 300,000 ppm for saturated brines from springs. The quality of the surface water in the Brazos River basin is discussed by areas and by stream reaches. This study indicates that the water of the Salt Fork Brazos River is too saline for most uses. The water of the Double Mountain Fork Brazos River is less saline and might be used for irrigation; however, it probably could not be used as a municipal supply or as a supply for most industries. The water of the dear Fork Brazos River is generally good but is adversely affected by brine pollution. Chemical-quality records for the Lampasas, Leon, and Navasota Rivers indicate that the water of these streams is of excellent quality; however, more data are needed to determine variations. The quality of the water in other tributaries could only be inferred from the results of miscellaneous sampling and from the probable effect of the underlying rocks. The weighted-average concentration of constituents in the Brazos River at Richmond indicated that inflow below Whitney Reservoir has a dilution effect on the river. For 12 of the 14 years of record, the weighted-average dissolved-solids concentration of the Brazos River at Richmond was lessi than, the 500 ppm maximum limit recommended by the U.S. Public Health Service (1961). This study indicates that water stored in Possum Kingdom and Whitney Reservoirs tends to become stratified, with the more saline water being at the greater depths. Samples collected in 1956 at Whitney Reservoir showed that the chloride concentration at the bottom was almost twice that at the surface. After a flood in June 1957, the dissolved-solids concentrations of bottom releases at Possum Kingdom were almost double those of surface releases through the spillway even though the flood volume had been more than twice the capacity of the reservoir. The quality of water in the lower main stem can be improved by control and disposal of brines in the upper basin. Also, the maximum concentrations in the water of the lower main stem can be lowered by dilution with water stored in reservoirs on tributaries that yield water of good quality.

Water Supply Paper↗