TEXAS WATER DEVELOPMENT BOARD

REPORT 180

RECONNAISSANCE OF THE CHEMICAL

QUALITY OF SURFACE WATERS OF

THE RIO GRANDE BASII\J, TEXAS

By

H. B. Mendieta United States Geological Survey

This report vvas prepared by the U.S. Geological Survey under cooperative agreement with the Texas Water Development Board

March 1974 TEXAS WATER DEVELOPMENT BOARD

John H. McCoy, Chairman Marvin Shurbet, Vice Chairman Robert B. Gilmore W. E. Tinsley Milton T. Potts Carl Illig

Harry P. Burleigh, Executive Director

Authorization for use or reproduction of any original material contained in this publication, i.e., not obtained from other sources, is freely granted. The Board would appreciate acknowledgement.

Published and distributed by the Texas Water Development Board Post Office Box 13087 Austin, Texas 78711

ii TABLE OF CONTENTS

Page

ABSTRACT...... •...... •....•.•...... •..•.•..•.•.•....•.•....•

INTRODUCTION . ....•....•.•....•....•.•....•.•.•..•....• 3

LOCATION AND EXTENT OF RIO GRANDE BASIN ...... •..•...•...... •....•.•.•..•.•..• 3

PHYSIOGRAPHY ...... •..•..... 3

CLIMATE...... 5

CULTURAL FEATURES AND ECONOMIC DEVELOPMENT . 5

ALLOCATION OF RIO GRANDE WATERS ...... •...... •..•....•.•...... •.•... 9

DEVELOPMENT OF SURFACE·WATER RESOURCES ...... •...... •.•..•...... • 9

STREAMFLOW RECORDS . 11

CHEMICAL·QUALITY RECORDS...... •...... •. 12

FACTORS AFFECTING CHEMICAL QUALITY OF WATER .. .•.. .. •.•...... •...... • 12

Geology ...... •....•....•.•....•.•....•... 14

Streamflow ...... •...... •...... •...... _...... • 14

Irrigation ...... •....•...... •...... • 17

Oilfield Brines __ _...... •...... 17

CHEMICAL QUALITY OF SURFACE WATER 17

Upper Rio Grande Basin ...... •...... '17

Middle Rio Grande Basin 18

Lower Rio Grande Basin . 25

Pecos River Subbasin 25

RELATION OF CHEMICAL QUALITY TO USE ...... •...... •...... 26

DOJTlestic Purposes ...... •...... 27

Industrial Use _ _ __ . 27

Irrigation 29

SUMMARy ...... ••....•.•.•....•....•...•..•..•.•.....••....•.•....•.•.•..•... 30

REFERENCES CITED . 33

iii TABLE OF CONTENTS (Cant'd.)

Page

TABLES

1. Reservoirs with Capacities of 5,000 Acre-Feet or More in the Rio Grande Basin in Texas ...... •...... •.•...... _..• .• .. 10

2. Source and Significance of Dissolved-Mineral Constituents and Properties of Water _...... •...... 13

3. Water-Quality Tolerances for Industrial Applications ...... • , •....•....•.•.. 28

4. Sodium and Salinity Hazards of Monthly Samples at Selected Sites in the Rio Grande Basin, 1960·68 31

5. Boron Concentrations in Monthly Samples at Selected Stations in the Rio Grande Basin, 1960-68 ...... •...... •..•.•.•..•.•.••• 31

6. Summary Index of Surface-Water Records in the Rio Grande Basin in Texas and Adjacent Areas in New Mexico and Mexico _...... •....•....•.•..•.•.•.. 36

7. Summary of Chemical Analyses of Texas Streams in the Rio Grande Basin ...... •..•.•....•..•.•.•.••.•.••••.•.. 41

8. Summary of Chemical Analyses at Selected Sites on the Rio Grande in New Mexico . 81

9. Summary of Chemical Analyses at Selected Sites on Mexican Streams in the Rio Grande Basin ...... •.•..•.•....•...... ••...... 84

10. Summary of Chemical Analyses at Miscellaneous Sites on Streams in the Rio Grande Basin ...... •....•.•.•..•.•..•.•....•.•.. 94

11. Discharge-Weighted Average of Chemical Constituents at Selected Sites in the Rio Grande Basin...... •...... • ....• .• .•....• 103

FIGURES

1. Index Map Showing River Basins and Coastal Areas of Texas 4

2. Map Showing Precipitation in the Texas Part of the Rio Grande Basin ...... _. 7

3. Graph Showing Average Annual Runoff, Drainage Area, and 1960 Population of Major River Basins in Texas, as Percentage of State Totals . 9

4. Geologic Map of the Rio Grande Basin in Texas and Mexico 15

5. Map Showing Irrigation in the Texas Part of the Rio Grande Basin ...... •...... •...... •. 19

6. Generalized Map of Oil and Gas Fields ...... •.•..•.•....•.•..•.•. 21

7. Discharge-Weighted Average of Dissolved Solids for the Rio Grande and Principal Inflow Stations ...... •..•.•..•.•....•...... •...... •.•. 23

iv TABLE OF CONTENTS (Cant'd.)

Page

8. Discharge-Weighted Average of Chloride and Dissolved Solids for the Pecos River Below Red Bluff Dam near Orla, Below Grandfalls, and at Girvin __ . 26

9. Diagram for the Classification of Irrigation Waters 30

10. Map Showing Location of Streamflow and Chemical-Quality Data-Collection Sites __ 111

v

RECONNAISSANCE OF THE CHEMICAL

QUALITY OF SURFACE WATERS OF

THE RIO GRANDE BASIN, TEXAS

By H. B. Mendieta ABSTRACT

The kinds and quantities of minerals dissolved in dissolved constituents in the middle reach of the Rio surface waters of the Rio Grande basin are related Grande. Water in the middle reach of the river usually is principally to the geology of the area and return flow fresh and very hard. from irrigation. Water from International Falcon Reservoir on the Rocks exposed in the Texas part of the basin range lower Rio Grande is used for municipal supply, industry, in age from Paleozoic to Quaternary. The upper reaches and irrigation. Return flow from irrigation causes of the Rio Grande and Pecos River in Texas traverse an increase in dissolved constituents downstream from deposits principally of Quaternary age. During periods the reservoir. when the flow consists principally of seepage from the Quaternary deposits and return flow from irrigation, The concentrations of dissolved solids and sulfate water in the upper reach of the Rio Grande usually is in the Rio Grande upstream from the Rio Conchas slightly saline and very hard. Water in the upper reach of usually exceed the limits recommended by the U.S. the Pecos River and most of its tributaries that traverse Public Health Service for drinking water. Water in the the Quaternary deposits is slightly to very saline and Pecos River and some of its tributaries is undesirable for very hard. domestic or industrial use because the water usually contains excessive concentrations of dissolved solids, Deposits of Tertiary age crop out in the upper, sulfate, and chloride. Water in most of the other streams middle, and lower reaches of the Mexican side of the Rio usually is suitable for domestic supply and many Grande basin and in the lower reach of the Texas side of industrial uses. However, the water usually is hard or the basin. Water in the Rio Conchas, the principal very hard and may requ ire soften ing for some uses. tributary that traverses the Tertiary deposits in the Mexican side of the basin, is fresh and very hard. The principal use of surface water in the Rio Grande basin is irrigation. The sodium hazard of water in Much of the middle reach of the Rio Grande basin the Rio Grande usually ranges from low to medium; that is underlain by rocks of Cretaceous age. Water in streams of the Pecos River usually is very high. The salinity that traverse these deposits usually is fresh and hard. hazard of water in the Rio Grande and Pecos River usually is high or very high. Thus, the long-term use of Inflow from the Rio Conchas and other tributaries these waters for irrigation will require special soil and from springs more than compensates for the saline management, good drainage, high leaching, and selection inflow from the Pecos River, and results in a decrease in of salt-tolerant crops.

RECONNAISSANCE OF THE CHEMICAL

QUALITY OF SURFACE WATERS OF

THE RIO GRANDE BASIN, TEXAS

INTRODUCTION The lower concentrations in the medium and flood flows are more representative of the water that would be This investigation of the chemical Quality of stored in reservoirs. Wherever possible, the sampling sites surface waters in the Rio Grande basin is part of a selected were at stream-gaging stations so that the statewide reconnaissance by the U.S. Geological Survey discharge-weighted averages and loads of dissolved in cooperation with the Texas Water Development constituents could be computed and the water quality Board. This report is the last in a series that summarizes could be related to flow conditions. the results of the study of each river basin and intervening coastal areas in Texas. (See list of references.) Figure 1 shows the area of the State covered LOCATION AND EXTENT OF by this report. RIO GRANDE BASIN

Selected water·quality data for the Rio Grande The Rio Grande rises in the San Juan Mountains in basin in Mexico and New Mexico are also included southwestern Colorado and flows southward across New because the chemical characteristics of water available Mexico to the edge of Texas near EI Paso. Thereafter, for use in Texas are influenced by inflow from these the river flows south and east for 1,250 miles, forming areas. the boundary between the United States and Mexico, and enters the Gulf of Mexico south of Brownsville, The purpose of this report is to present, integrate, Texas. and summarize selected chemical-quality data that will aid in the proper development, management, and use of The Rio Grande basin encompasses an area of the water resources of the basin. about 335,000 square miles, 135,900 square miles of which are in the United States. Included within this Most of the water-quality data for the Rio Grande area-in Colorado, New Mexico, Texas, and Mexico-are and adjoining irrigation drains have been collected by large closed basins with internal drainage, and only the International Boundary and Water Commission, about 89,000 square miles in the United States and United States and Mexico. However, the U.S. Bureau of 93,000 square miles in Mexico contribute runoff to the Reclamation and the U.S. Geological Survey have Rio Grande. The Texas part of the Rio Grande basin, the maintained sampling points on the main stem for short largest basin in the State, includes an area of about periods. Most of the data for the Pecos River basin in 48,300 square miles (Figure 1), of which about 9,500 Texas have been collected by the U.S. Geological Survey square miles is noncontributing. in cooperation with the Texas Water Development Board and its predecessors. During the extensive interagency The principal tributaries that join the Rio Grande Pecos River Joint Investigation in 1938-40 (National downstream from EI Paso are the Pecos and Devils Resources Planning Board, 19421, the U.S. Geological Rivers on the Texas side and the Rio Conchos, Rio Survey made the chemical-quality studies. Salado, Rio Alamo, and Rio San Juan on the Mexican side. To supplement data available from these and other' chemical-quality programs, the Geological Survey periodically collected and analyzed water from selected PHYSIOGRAPHY sites within the Texas part of the basin. Whenever possible during this reconnaissance, water-quality data The Rio Grande basin in Texas is in parts of three were collected over a range of flows. The dissolved-solids provinces in three major physiographic divisions-the concentrations are likely to be highest during low-flow Basin and Range province of the Intermontane Plateaus, periods and contributions by ground-water inflows, the Great Plains province of the Interior Plains, and the irrigation returns, and municipal and industrial Coastal Plain province of the Atlantic Plain. (Fenneman, discharges usually can then be more easily identified. 1931).

·3· i-"------.-..------.----.., [ ,i

o

f. ~ 1 ~~~~~:Do tol COLORAOC- LAVACA o LAVACA­ Gl,IAD~UPE

Figure 1.-River Basins and Coastal Areas of Texas

The area between the Rio Grande and the Pecos elongated desert lowlands. The Mesilla Valley is on the River subbasin, commonly referred to as the west. The Franklin Mountains, the Hueco bolson, the "Trans-Pecos region," is part of the Mexican Highland Diablo Plateau including the Hueco and Finlay and Sacramento sections of the Basin and Range Mountains, the Salt basin, and the province. The Trans-Pecos region is characterized by Guadalupe-Delaware-Apache Mountain chain complete block plateaus and mature block mountains of gently to the eastward sequence. The general trend of these land strongly tilted strata and undrained desert basins known features is to the south or southeast. as "bolsons." A series of mountain ranges, mesas, and peaks extends from the Big Bend of the Rio Grande The mountains and high plateaus in the southern northwestward into New Mexico. Although these part of the Mexican Highland section are predominantly mountains are old and have been eroded severely, the igneous and volcanic rocks that have block faulted, altitude of their highest peaks generally is more than flexed, tilted, and strongly folded to create the irregular 7,000 feet and is about 8,750 feet at Guadalupe Peak. topography of the Big Bend. The Davis Mountains is the largest group of volcanic mountains. With peaks up to The northern part of the Mexican Highland section 7,835 feet, the Chisos Mountains in the Big Bend and the Sacramento section generally are divided into National Park are highest of the volcanic groups. The three relatively mountainous areas separated by Sierra del Carmen, Santiago, and Del Norte Mountainson

- 4- the eastern part of the Big Bend are the southernmost maritime influence of the prevailing wind. Here, the highlands in the Basin and Range province. winters are mild and the summers hot. At higher altitudes, the upper basin has an alpine climate with The Pecos River valley and the central part of the warm days and cool nights in the summer; winters Rio Grande basin as far south as Del Rio lie either in the usually are cool or cold. Pecos Valley, the Edwards Plateau, or the High Plains sections of the Great Plains province. The Pecos Valley section in Texas is an alluvium-filled valley that extends CULTURAL FEATURES AND from New Mexico to near Grandfalls where a thin wedge ECONOMIC DEVELOPMENT of the High Plains section separates it from the Edwards Plateau section to the south. Although the Rio Grande basin contains more than 19 percent of the area of Texas, the basin The part of the Edwards Plateau west of the Pecos contributes less than 2 percent of the total runoff from River is known as the Stockton Plateau. Both in the the State and has only about 9 percent of the State's main part of the Edwards Plateau east of the Pecos River total 1960 population (Figure 3). The percentages cited and in the Stockton Plateau to the west, the highland include the adjacent coastal area, which is almost plain is characterized by a cap of resistant limestone. entirely dependent on the irrigation water diverted from Draws that grade into deep gullies and V-shaped valleys the Rio Grande. dissect the plain, exposing the less resistant limestone. In areas of fissured limestone, recharge of the aquifers is The bulk of the population in the basin is rapid. These aquifers discharge through springs near the concentrated in the metropolitan areas of EI Paso perimeter of the plateau. (population 317,462 in 1970), Laredo (population 65,491 in 1970), and the McAllen, Harlingen, At the edge of the Edwards Plateau, the Balcones Brownsville area of the Lower Rio Grande Valley Escarpment defines the beginning of the West Gulf (population approximately 325,000). Smaller Coastal Plain section of the Coastal Plain province. Here, concentrations of population are centered in towns such the Texas part of the Rio Grande basin is a narrow strip as Pecos, Fort Stockton, Del Rio, and Eagle Pass. of dissected coastal plain. The part of the plain farthest from the Rio Grande is rolling. Nearer the Rio Grande, Ranching is the most widespread enterprise in the the area is dissected by the valleys of the intermittent Rio Grande basin. Except for small irrigated areas near tributaries and the surface is rougher. In the Lower Rio El Paso and in the LowerRio Grande Valley, many acres Grande Valley, the basin is restricted to the relatively of arid or semiarid land are required to graze one head of narrow flood plain or narrow terraces, generally less than cattle. Thus, the ranches usually are large and the 4 miles wide. number of cattle few. In the middle region of t,he basin where the Edwards Plateau is rough and rocky, sheep and goats are the principal livestock. Dryland farming CLIMATE within the basin usually is restricted to forage crops for use on the ranches. Hunting lease revenue is a significant The climate of the Rio Grande basin ranges from source of income for most basin ranchers. semiarid to arid (Thornthwaite, 1952). The mean annual precipitation is about 26 inches in the eastern part of the Cotton is the principal crop grown on irrigated Lower Rio Grande Valley but progressively declines to areas within the basin. Long-staple cotton is grown in 20 inches in the western part of the lower valley the El Paso area and to a smaller extent in the Pecos (Figure 2). However, in some areas adjacent to the Rio area; short-staple cotton is grown on irrigated areas along Grande in the middle part of the basin, the annual the middle basin and in the Lower Rio Grande Valley. rainfall averages 18 to 20 inches. Planting and harvesting of this crop is almost entirely mechanized so that little physical labor is required. Through the Pecos River subbasin and westward to the Big Bend, the mean annual rainfall diminishes Alfalfa is an important crop in the EI Paso area rapidly from 20 to 8 inches. In the Trans-Pecos part of where it is the base for a diversified Iivestock industry the basin, the rainfall generally increases with an increase which includes feedlot operations, dairying, and swine in altitude. Rainfall in some of the high areas averages as and poultry raising. much as 20 inches annually; but toward the internal basin or bolson, 10 inches is normal. As little as 8 inches Vegetable crops are produced throughout the is normal in the strip immediately adjacent to the Rio irrigated areas in the basin. In the EI Paso area, the crops Grande. are diversified to serve the needs of an isolated trade area. In the Pecos area, the small yet intensive Most of the middle and upper parts of the Rio production of cantaloupes is a speciality. From Laredo Grande basin in Texas have a typical continental climate to the Lower Rio Grande Valley, the winter vegetables with wide daily temperature fluctuations. In the lower and early spring crops are of national importance. In Rio Grande basin, the climate is tempered by the recent years, grain sorghum has become a high-yielding, profitable crop in all irrigated areas.

- 5-

24,------,,,-, ~ ~ 221---- EXPLANATION ------:~-----~------~- , ~ 0 RutlOff tlrOll'l areo in Tnal Of'Ilyl ----~---- Il_ 201--- .... ~ lS o DroinoQ8 Ofeo Un Tuosl ~ t:: ~ ..g 18 f---- 1m PopulotlOl'l (in Tnas) ---- "---lilljf--~--oli--~------__f:+___i ~ --:. ~ ~ ~ ~---l t:----.'"l!II--~-.¥'1.:------'=:------f. - i::I------••• i - 15 12 1----,,,=c------Ifr- ![1i~ - l------'I-- ~--VA--l

~ 10 ~ 1~1:r-"Er- f;t---VA------i--,,";---t f-

~ 8 -~- ::!j~ !j]r- ."- ~ -~- +------I~1iir_ 6 ;: iii 1- ..- _f;l·J_--,~-,====f- ~ 4HVl----i ~-i!]lr-ii!: 1- •••• ,1--;;;f'1-l 1-1 I.~ ~ :~ rr ~!! fit M'---'"i11/t'''''''-Jl

Figure 3.-Average Annual Runoff, Drainage Area, and 1960 Population of Major River Basins in Texas, as Percentage of State Totals

Oil operations are the principal source of revenue Quitman to the Gulf of Mexico. The treaty also calls for in much of the Pecos River subbasin. Most of the oil as many as three major storage dams to provide for production in Webb, Zapata, and Starr Counties is just water supply, flood control, and the generation of outside the Rio Grande basin, but the basin communities hydroelectric power. The International Boundary and receive the bul k of the business from these operations. Water Commission administers the responsibilities and obligations set forth by the treaty. Tourism is another important industry. Increasing numbers of people are visiting the Big Bend National The Rio Grande Compact, approved by the Park and retired or semi-retired persons find the lower legislatures of Colorado, New Mexico, and Texas in valley an annual winter retreat. 1939, allocates the uncommitted waters of the Rio Grande above Fort Quitman. Water-delivery schedules are provided from Colorado to New Mexico, from New ALLOCATION OF RIO Mexico to Texas, and to the various irrigation projects. GRANDE WATERS The waters from the drainage area of the Pecos Two treaties between the United States and River were allocated by the Pecos River Compact Mexico provide for the division of international waters approved in 1949 by Texas and New Mexico. The of the Rio Grande. The Rio Grande Compact between Compact also provides for cooperative programs for the Colorado, New Mexico, and Texas and the Pecos River salvage of water used by phreatophytes and for Compact between New Mexico and Texas provide for alleviation of the excessive salinity of the Pecos River. the division of interstate waters (Texas Water Development Board, 1968), DEVELOPMENT OF The United States and Mexico signed a treaty in SURFACE-WATER RESOURCES 1906 providing for the delivery of 60 thousand acre-feet of Rio Grande water annually by the United States to Because rainfall, streamflow, and runoff within the Mexico in the El Paso-Juarez valley above Fort Quitman. Rio Grande basin are unevenly distributed, storage Deliveries are in proportionate amounts when the Rio projects are required to provide dependable quantities of Grande Compact has shortages. A treaty ratified by the surface water for municipal supply, irrigation, and United States and Mexico in 1945 dealt with the division industrial use. The capacity, owner, location, and use of of waters from the Rio Grande, the Colorado River, and the principal reservoirs in the basin are listed in Table 1 the Tijuana River. The section pertaining to the Rio (Dowell and Breedin9, 1967), Grande allows for the allocation of waters from Fort

-9 - Table 1.-Reservoirs With Capacities of 5,000 Acre-Feet or More in the Rio Grande Basin in Texas (From Dowell and Breeding, 1967)

The purpose for which the impounded water is used is indicated by the following symbols: M, municipal; I, industrial; Ir, irrigation; R, recreation; P, hydroelectric power; Fe, flood control.

.1JTOTAL STORAGE YEAR OPERATION CAPACITY NAME OF RESERVOIR BEGAN STREAM (ACRE-FEET) OWNER COUNTY USE

San Esteban Lako 1911 Alamlto Creek 18.770 Mrs P. M. Robinson estate Presidio I,

Red Bluff Roservoir 1937 Pecos River 310,000 Red Bluff Water Power Eddy (New Mexicol, I, Control District Reeves, aJ)d Loving

Lake Balmorhea 1917 Sandia Creek 6,350 Aeeves County Water Reeves I, Improvement District No.1

Devils Lake Y 1928 Devils River 9,200 Contral Power & Light Co. Val Verde p

Lake Walk Y 1929 Devils River 5,400 Central Power & Light Co. Val Verde P

International Amistad Reservoir 1968 Rio Grande 5,325,000 United States and Mexico Coahuila, Mexico and M,l. a Val Verde, Texas FC, Ir, P, R

Casa Blanca LClke 1951 Chacon Creek 20,000 Webb County Webb A

International Falcon Reservoir 1953 Rio Grnnde 3,280,700 United States and Mexico Tamaulipas, Mexico, M, I, and Starr and Zapata, Fe, Ir, P, R Texas

.Y Totat storage capacity is that capacity below the lowest uncontrolled outlet or spillway and is based on the most recent reservoir survey available. V Inundated by International AmistCld Reservoir. Throughout history, irrigation has been the Ownership has changed several times. In 1962, the Texas dominant use of Rio Grande waters. The Indians Water Commission reduced the water rights to 400 irrigated small plots along the upper valley of the Rio acre-feet to irrigate 200 acres of land. Grande for centuries_ Later, the Spanish colonists, who considered river water for irrigation as a commodity Devils Lake and Lake Walk on the Devils River essential to the survival of the communities, established completed in 1928 and 1929 respectively, wer~ riparian rights to the water. constructed by Central Power and Ught Company for development of hydroelectric power. These two Irrigation in the Rio Grande basin was expanded reservoirs were inundated by International Amistad greatly when the frontier forts were established by the Reservoir in 1968. United States. In 1853, water from San Solomon Springs and other springs in the vicinity of Balmorhea were used Casa Blanca Lake on Chacon Creek. 3 miles for irrigation of corn, alfalfa, and other produce raised northeast of Laredo, was completed in 1951 by Webb for consumption in the Fort Davis community. County for recreation and irrigation of a golf course. Springflows were utilized by direct diversion until 1917 when Lake Balmorhea was completed to impound the International Falcon Reservoir. 80 miles flow diverted from Phantom Lake Springs, the Madera downstream from Laredo, and International Amistad Diversion Dam on Toyah Creek, and San Solomon Reservoir, 12 miles northwest of Del Rio, are the largest Springs. reservoirs in the Rio Grande basin. International Falcon Reservoir, which has a capacity of 3,280,700 acre-feet at The drainage area of Sandia Creek and the Madera the top of the spillway gates, was completed in 1953. Canal collecting system. which contributes inflow to the International Amistad Reservoir, which has a capacity of reservoir, is only 22 square miles; and the original 5,325,000 acre-feet at the top of the flood-control capacity of the reservoir was 6,500 acre-feet. storage space, was completed in 1968. Both of these Nevertheless, an annual diversion of 18,000 acre-feet of multipurpose reservoirs were constructed under the water from the reservoir was authorized for the 1944 treaty between the United States and Mexico, irrigation of 10,600 acres. which called for equitable distribution of the waters of the Rio Grande. In the 1860's, Comanche Springs was used as a water supply for Fort Stockton. Miles of canals were constructed to irrigate several thousand acres of arid STREAMFLOW RECORDS land, and shortly thereafter all the flow of the springs was being fully utilized. Streamflow records for the Rio Grande date from 1889 when the gaging station, Rio Grande at El Paso, Irrigation from the Pecos River in the area from was established by the U.S. Geol09ical Survey (Table 6). Red Bluff, New Mexico to Girvin, Texas began in 1877. A number of stations on the main stem downstream An era of construction of canals and small off-channel from El Paso were established in 1900 and were reservoirs began in 1888 and continued for more than 35 operated until 1914. Operation of these stations was years. By 1915. 10 major irrigation projects had been suspended from 1914 to 1923, except for a few months started within a 125-mile reach of the Pecos River. in 1919. From 1923 to 1931, gaging stations were Undependable water supply, soil and water salinity, and operated independently by the United States and the lack of technology plagued the projects; and several Mexico. In 1932, the International Boundary and Water reorganizations of projects and water districts took Commission took over the operation of most of the place. In 1934, through the efforts of seven irrigation streamflow and water.quality stations to determine an projects, plans were made to finance and construct Red equitable distribution of waters between the United Bluff Dam, which was completed in 1936. Releases from States and Mexico. Records of these stations have been Red Bluff Reservoir have been used to irrigate as much published jointly by the United States and Mexican as 28,000 acres, but the amount used varies with the Sections of the Commission. Figure 10 shows the quantity and quality of the water in storage. Since 1940, location of the principal data-collection sites. ground water of fair to marginal quality has been used in Ward and Reeves Counties to supplement surface-water The collection of streamflow records for the Pecos supplies. River was begun in 1898 when the U.S. Geological Survey established the stream-gaging station Pecos River San Esteban Lake on Alamito Creek, the first near Comstock_ Since 1900, the International Boundary reservoir in the Rio Grande basin in Texas, was and Water Commission has maintained a gaging station completed in 1911 by the St. Stephens Land and at or in the vicinity of this site. The high bridge that Irrigation Company_ This project included the 18,770 supported the gage near Comstock was destroyed by a acre-foot reservoir and 7 miles of canals. The permit flood in 1954, so the flow of the Pecos River was from the Texas Board of Water Engineers allowed for measured upstream near Shumla until 1967 when the the irrigation of 8,500 acres of land, but because of lack gaging station Pecos River near Langtry was established. of runoff, the lake has been dry most of the time. The most intensive records of streamflow for the Pecos

- 11 - subbasin vvere compiled as part of the Pecos River Joint the early 1930's, the system of discharge-weighted Investigation (National Resources Planning Board, composites was adopted. 1942). In 1937, 31 recording stations were operated on the main stem, tributary streams, canals, and drains. A composite sample was made for each month at each station by consolidating into a single sample an Streamflow at many miscellaneous sites on the amount of each individual sample proportional to the Pecos River was measured during low-flow and river flow at the time the sample was taken. The results water·delivery studies in 1964, 1965, 1967, and 1968 of these analyses and corresponding streamflow records (Grozier and others, 1966 and 1968; Spiers and Hejl, were used to calculate annual discharge-weighted 1970). Records of diversion from scores of sites on the averages of selected constituents for each station, Rio Grande and Pecos River have been maintained by provided the records were considered sufficient. The the International Boundary and Water Commission, the International Boundary and Water Commission U.S. Geological Survey, and the U.S. Bureau of calculates weighted averages on a calendar-year basis. In Reclamation. this report, the calendar year was retained as the reporting period for stations operated by the Boundary Records of discharge and stage of streams and Commission. However, annual weighted averages for contents and stages of lakes and reservoirs from 1897 to stations operated on the Pecos River by the U.S. 1968 have been published in the annual series of U.S. Geological Survey were calculated on a water-year Geological Survey Water·Supply Papers and by the (October 1-September 30) basis. International Boundary and Water Commission Water Bulletins. Beginning with the 1961 water year, Chemical-quality records for the Rio Grande basin streamflow records have been released by the Geological are summarized in Tables 7-11. Complete records are Survey in annual reports. (See table in list of references.) published in an annual series of the U.S. Geological Summaries of discharge records giving monthly and Survey Water-Supply Papers, in reports of the Texas annual totals have been published by the Texas Board of Water Development Board and its predecessor agencies, Water Engineers (1958) and the U.S. Geological Survey and in the International Boundary and Water 11960,1964a). Commission Water Bulletins. (See table in list of references.)

CHEMiCAL·QUALITY RECORDS FACTORS AFFECTING CHEMICAL Daily records of water quality for the Rio Grande QUALITY OF WATER in Texas date from August 1, 1905, when the U.S. Geological Survey began sampling at the station Rio Surface water normally contains significant Grande at Laredo (Table 6). Sampling at this station was amounts of dissolved or suspended materials. These and discontinued after one year. The next regular sampl ing other constituents or properties such as color, taste, record dates from 1924 when the U.S. Bureau of natural and man-made organic substances, radioactive Reclamation began collecting data on the concentrations metals, and microorganisms are factors that determine of sediment and dissolved solids at the station Rio water quality. In this report, only the major chemical Grande at El Paso. constituents are considered because these are the principal factors that limit the use of the water in the Beginning in 1928 and 1929, samples were Rio Grande basin. collected at approximately weekly intervals for the determination of specific conductance and major The major chemical constituents usually are chemical constituents on the Rio Grande at EI Paso, dissociated into charged particles or ions. Principal Fabens, and Fort Quitman. Monthly or less frequent cations (positively charged ions) in natural water are sampling and analysis were begun in the 1930's at several calcium (Ca), magnesium (Mg), sodium {Nal, potassium other stations in Texas by the U.S. Geological Survey, (K), and iron (Fe). Principal anions (negatively charged the United States Section of the International Boundary ions) are carbonate (C03), bicarbonate (HC03), sulfate and Water Commission, and the U.S. Bureau of (S04), chloride (CI), fluoride IF), and nitrate (N03). Reclamation. The samples collected by the Commission The source and significance of the constituents and were analyzed by the U.S. Department of Agriculture at properties commonly determined by the U.S. Geological Riverside, California. Survey are given in Table 2.

Sampling intervals at regular stations have varied Some of the environmental factors that affect the widely. From one to 31 samples during a month have chemical quality of surface waters are climate, geology, been collected and analyzed. At times, estimated values patterns and characteristics of streamflow, for constituents have been reported as representative of impoundments and diversions, disposition of municipal a month's flow. During the early years, each individual and industrial wastes, and irrigation. In the Rio Grande water sample collected by the International Boundary basin, the principal factors that affect the chemical and Water Commission was analyzed. However, during quality of the water are geology and return flow from irrigation.

·12· Table 2.-Source and Significance of Dissolved-Mineral Constituents and Properties of Water

CONSTITUENT OR SOURce OR CAuse SIGNIFICANCE PROPERTY Silica (SI02) Dissolved from practlally all Forms hard scalI In pIpes .nd boilan. C.rried over In steam of rocks and soils, commonly len nigh pressurl boillrs to form deposits on bl.des of turbines. than 30 mgll. High concentra· Inhibits deterior.tlon of lIolite-type wetlr soheners. tlons. as much lIS 100 mgll, oenar· ally occur In !'Ilg!'lly .lk.lIn. wlters.

Iron (Fe) Dluolved from pnctic.lly III On .xposurl to air, iron in ground water oxidizls to reddish­ rocks Ind soili. MlY 1110 be brown precipitate. Marl th.n .bout 0.3 mQ!lsuinslaundry and dlrlved from Iron plpl'S, pumps, utenslls reddish·brown. Objlctlonlble for food processing, tex­ and ot!'l... equlpmlnt. More t!'l.n tile processing. bevlr.gls. iCI m.nuf.cturl, brewing, and other 1 or 2 mgll of Iron In suri.c. processes. U.S. Public Hulth S.rvlce (1962) drinkinQ-wat.r w.te~ gener.lly indic.t.s .cld standards state that Iron snould not .xceed 0.3 mglL Larg.r w.stes from mine dr.lnlge or qUlntities cau.. unpl••sant teste .nd hvor growth of iron other sourcl'S. bacteria.

Calcium ICal and DIssolved from pr.ctic.lly .11 solis C

Sodium (Na) and Dissolved from practlc.lly all Large amounts, in combination with chloride, give a saity taste. potassium (K) rocks end soils. Found OIlso in MOderate quantities nlvI little eHeet on the us.fulness of water encient brines, sel water, indus· for most purposes. Sodium saln mOllY CilUse foaming in $team tri.l brines, .nd sew.ge. boilers and a high sodium content may limit the use of wilter for Irrigation.

Bicarbonate (HC03 ) Action of carbon dlo"lde in water BicOlrbonOlt. OInd carbonate produc••Ikallnlty. Blcarbon.tes of and carbonate (C03) on carbon.te rocks such as lime­ calcium and magnesium decompose in steam boil.rs and hot none and dolomite. water facilities to form scaie and rel.ase corrosiv. cilrbon dioxide gas, In combination with calcium and m.gnesium, cause carbon­ ate hardness.

Dinolved from rocks and soils Sulh,te in ..... ater containIng calcium forms hard scale in steam cont.lning gypsum. iron sulfides, boilers. In large amounts, sulf.te In combin.tion with otner ions OInd other sulfur compounds. gives bitter taste to water. Some calcium sulfate is considered Commonly present In mine waters benefici.1 in the br.wing proc.ss. U.S. Public H.alth Service and In some industrial wastes. (1962) drinklng·water standards recommend t!'l.t the sulfate content should not exceed 250 mgll.

C!'Iloride (el) Dissolved from rocks and solts. In large amounts In combination with sodium, gives salty taste to Present in SBwage .nd found In drinking wat.r. In lug. Quantities, incr.ases the corrosl..... ness of large amounts in ancient brines, water. U.S. PUblic Health Service (1962) drinking·water stan· sea water, and Industrial brines. dards recommend that the cnloride content shOuld not e"ceed 250 mgll.

Fluoride (Fl Dissolved in small to minute Fluoride in drinking water reduces the incid.nc. of tooth decay qUOlntities from most rocks Ind wh.n tne water Is consumld during the period of enamel soils. Added to many waters by calcification. However, it may cause mottling of the teeth, fluoridation of municipal suP­ depending on the concantration of fluorid., the age of the child. plies. amount of drinking water consumed, and susceptbility of the individual. (Mai.r. 1950)

Decaying organic m.tter, seWOlgB, Concentr.tion mucn gre.ter th.n the local t1verage may suggest fertiliun, and nitt.tes in soil. pollution. u.S. Public He.lth Slrvlc. (1962) drinking--water standards suggest a limit of 45 mgtl. W.ters of hign nitrate content h8Ye b.en reported to be the cause of methemoglo­ binemia (an oft.(l f.tal disease in inf.nts) and tnerefore should not be used in infant feeding.. Nitrate has been shown to be helpful in reducing inter-crysUilllne crackIng of boiler steel. It encourages growth of alg•••nd other orQilnisms which produc. und.sirable testes .nd odors.

Dluolved solids Chiefly mlner.' const' :ents dis­ u.s. Public H••lm SeNice (1962) drinking-water standards solved from rocks .nd solis. recommend that WOlt." conUilnlng mar. thOln 500 mgll dissolved Includes some w.tlr of crystalli­ solids not be used if other less min.raliled supplies are available. zation. Waters containing more than 1000 mgtl dissolved solids are unsuiteble for many purposes.

Hardness as Cac03 In most w.ters nearly all tha Consumes soap before a l.thlr will form. Deposits soap curd on !'Iardn"s is dUI to calcium and batntubs. Hard weter forms scale In boit.n, water heaters, and magnesium. All thl met.llic pipes. H.rdness equiv.llnt to thl blcarbon.t••nd c.arbonate is cations othlr th.n the alkali called carbonate h.rdness. Any htlrdness in ."c.ss of this is metals also c.use hardness. called non-c.rbonat. !'I.rdness. Wat.n of hardness as much as 60 ppm are considered soh: 61 to 120 mWI, moderately hard; 121 to lBO mQll, hOlrd, mora th.n 1BO mgll, very hard. Specific conductance Mi....r.1 contlnt of the w.tar. Indicates d.gree of mineraliz.tlon. Specific conductance Is a (microm!'los at 250 C) measure of the capacity of tna w.t.r to conduct an electric curr.nt. Vuies with concentration al'\d degree of ionization of the constit\J.ntl.

Hydrogen ion Acids, acid-generating salts, .nd A pH of 7.0 indic.tes neutrality of a solution. V.lues higher man concentration (pH) free carbon dioxide lower thl pH. 7.0 denote increasing .,k.,lnity: values lower tn.n 7.0 indicate Carbon.tes, bicarbon.t.s, hydrox­ increning OIcidity. pH is I measure of thl OIctivity of the ides, end phosphates, sllicates, hydrog.n ions. Corrosiveness of water generOltly increa5t!s with and borat.s rai.. the pH. decreasing pH. Howev.r, ."c.nively Ilklline waten may also attack m.tals.

- 13 - Waters usually are classified in various ways to Chemical analyses of surface water at selected sites demonstrate similarities and differences of composition. in the Rio Grande basin are represented In the following discussion, which relates chemical diagrammatically (Stiff, 1951) in Figure 4 to relate quality of water to environmental factors, water is chemical composition to geology. The shape of each classified on the basis of dissolved-solids content in mgll diagram indicates roughly the degree of mineralization. (milligrams per liter), principal chemical constituents, and hardness. On the basis of dissolved-solids content, The upper reaches of both the Rio Grande and waters are classified as follo'NS: Pecos River in Texas are underlain primarily by deposits of Quaternary age. In the fall and winter, when no water D ISSOLVED SOLI DS is being released from reservoirs in New Mexico, water in CLASSIFICATION IMG/LI the Rio Grande at El Paso is usually slightly saline and Fresh Less than 1,000 very hard. The principal cation in the water is sodium; the principal anion usually is sulfate, but in some of the Slightly saline 1,000 to 3,000 more highly mineralized water, the percentage of Moderately saline 3,000 to 10,000 chloride increases (Figure 4).

Very saline 10,000 to 35,000 Farther downstream at Fort Quitman, the quality Brine More than 35,000 of water in the Rio Grande is altered by irrigation return flows. Water passing the Fort Quitman station usually is slightly saline and very hard. Although the principal As to geochemical types, waters are classified on chemical constituents vary, highly mineralized flows the basis of the predominant cations and anions in me/l usually are of the sodium chloride type (Figure 4). (milliequivalents per liter)_ For example, water is classified as a sodium chloride type if the sodium and In the reach between the daily chemical-quality chloride ions constitute 50 percent or more of the stations Pecos River below Red Bluff Dam near aria and cations and anions respectively. Waters in which one at Girvin, which is underlain principally by deposits of cation and one anion are not clearly predominant are Quaternary age, the water usually is moderately or very recognized as mixed types and are identified by the saline, very hard, and of the sodium chloride type. Water names of all the important cations and anions. in most tributaries to the Pecos River that traverse rocks of Quaternary age is slightly to very saline, very hard, On the basis of hardness, waters are classified as and of the sodium chloride or mixed sodium chloride soft, moderately hard, hard, or very hard (Table 2). sulfate type. However, water in Coyanosa Draw is fresh, ranges from moderately hard to hard, and is of the calcium bicarbonate type (Figure 4). Geology Extensive deposits of Tertiary age crop out in the The amounts and kinds of minerals dissolved in upper, middle, and lower reaches of the Mexican side of water that drains from areas where municipal and the Rio Grande basin and in the lower reach of the industrial influences are small depend principally on the Texas side. The Rio Conchas is the principal tributary chemical composition and physical structure of the that traverses rocks of Tertiary age on the Mexican side rocks and soils traversed by the water and on the length of the basin. Water in the Rio Conchas near Ojinaga of time the water is in contact with the rocks and soils. usually is fresh, very hard, and of the sodium calcium The amount of minerals available for solution is sulfate type. Water in the Rio Grande at Johnson Ranch decreased by leaching; therefore, in areas of high rainfall, near Castolon, which is contributed principally by the the mantle rock and residual soil contain relatively small Rio Conchas, is usually fresh and very hard. Principal amounts of readily soluble minerals. These rocks usually chemical constituents usually are calcium, sodium, and yield water of low mineralization. However, in arid or sulfate IF igure 4). semiarid regions, most soils and rocks are incompletely leached and still contain large amounts of readily soluble The middle reach of the Rio Grande basin is material; water in contact with these rocks and soils may underlain principally by rocks of Cretaceous age. become highly mineralized. Streams that traverse the Cretaceous outcrops include the Devils River and San Felipe Creek on the Texas side The rocks exposed in the Texas part of the basin and Rio San Diego and Rio San Rodrigo on the Mexican range in age from Paleozoic to Quaternary (Figure 4). side_ Water in these streams usually is fresh, hard, and of The structure of the rocks and sediments of the basin the calcium bicarbonate type (Figure 4). varies from extremely complex arrangements of several systems in the upper part of the basin to an orderly layering of Tertiary and Quaternary sediments in the Streamflow lower basin (Davis and others, 1965). The geology in Mexico is adapted from the "Carta Geologica de la The patterns and characteristics of unregulated Republica Mexicana" prepared in 1968 by the Comit~ streamflow usually affect the chemical character of the de la Carta GeolOgica de Mexico.

- 14 - water in streams. Water discharge, and thus the chemical Oilfield Brines quality, of any unregulated stream may vary from day to day and even from hour to hour. The variation may be Oil is produced in large areas of the Pecos River large, such as for smaller streams that flow subbasin, in the middle reaches of the Rio Grande basin, intermittently in response to storms, or small, if the river and in the Lower Rio Grande Valley. The principal is large or if the flow is derived primarily from ground oil-producing areas (Figure 6) extend eastward from the water. middle Rio Grande basin and southward from the Lower Rio Grande Valley. Thus, oilfield brines may be The concentration of dissolved minerals usually transported into or out of the basin. varies inversely with the water discharge. The concentrations usually are minimum during periods of Improper disposal of brines from these areas has high flow because most of the water is surface runoff permitted salt to reach the streams. When oil production that has been in contact with soluble minerals of the started more than fifty years ago, little effort was made exposed rocks and soils for a relatively short time. In to protect either surface or ground waters in the area. arid areas, intermittent streams may have high Unlined surface pits were usually employed to hold the concentrations of dissolved solids at times of high flow brine produced with the oil. Though some of the water when an isolated rainstorm causes only enough flow to from the pits evaporated, the greater part probably scour the streambed. percolated downward and contributed to the salinity of the streams. Brines from abandoned wells and Behveen rainstorms, the flow of perennial streams unplugged, or improperly plugged, test holes may also is sustained predominantly by ground water from springs contribute to the salinity of streams. or seeps along the watercourse. This water has been in contact with the rocks and soil for sufficient time to In recent years, the trend has been to inject the leach appreciable quantities of soluble material and to brines back into the producing formation to maintain reach equilibrium. Thus, the concentration of dissolved the formation pressure. Brackish or salt water from materials usually is maximum and is nearly constant other sources may also be injected to repressure the during low-flow periods. oil-producing formations. Though injection usually is the preferred way of brine disposal, the increased pressure Through most reaches of the Rio Grande and the may move the brine upward along fault zones or into Pecos River, the flow is so regulated by upstream unplugged or improperly plugged wells and eventually reservoirs, diversions, and drainage returns that only at into surface streams. medium or high flows do the normal discharge-concentration relations apply. The composition of oilfield brines varies; but the principal chemical constituents in order of the magnitude of their concentration (milligrams per liter) Irrigation are usually chloride, sodium, calcium, and sulfate. Generally, an erratic variation in the ratio of the chloride Because most of the Rio Grande basin is either ion to other major constituents in streams that drain arid or semiarid, and because most of the water is used oilfields indicates brine pollution. for irrigation, repetitive and consumptive usage of water is greater here than in most of the major river basins of Because much of the flow of the Pecos River is North America. Before 1900, shortages of water for naturally saline, detailed studies are necessary to identify irrigation began to occur. Since that time, the total the source and quantities of brines contributed by acreage of irrigated lands has been restricted and oilfield operations. irrigation rights have been reallocated to achieve the maximum use of available water (Figure 5). CHEMICAL QUALITY OF Irrigation returns from surface and ground waters SURFACE WATER have a significant effect on the use and the quality of the water available throughout the entire reach of the Rio Upper Rio Grande Basin Grande and the Pecos River. The natural quality of water in these streams, which is only marginal or fair, is The flow of the Rio Grande upstream from Texas being seriously impaired by the return flow of water is regulated by Elephant Butte and Caballo Reservoirs in used repetitively for irrigation. The higher salinity of the New Mexico and is derived principally from snowmelt. irrigation return flow is caused by the salinity of the soil The quality of the water released from these reservoirs is through which the water has percolated and by the fairly constant. The discharge-weighted average of the concentration effect of high evaporation rates dissolved-solids concentrations at Caballo Dam for the throughout the basin. period of record from 1939 to 1948 was about 500 mg!I, and no monthly composite contained as much as

- 17 - 1,000 mgt!. Downstream at Leasburg Dam during the periods, the discharge-weighted average concentrations same period, the dissolved solids were less than 5 percent of dissolved solids for the Fort Quitman station reached higher. However, the discharge-weighted average their lowest values (375 mgtl in 1956,294 mgtl in 1957, concentration of dissolved solids for the same period at and 375 mgtl in 19651. These waters of low the EI Paso station was 34 percent greater than that at mineralization were from local storm runoff contributed Leasburg Dam. Most of this increase in concentration by streams downstream from the irrigated valley of the resulted from irrigation return flows from the Mesilla Rio Grande. When a substantial part of the annual flow Valley irrigation project. at Fort Quitman is from the flow passing the station near Acala or from irrigation return flow, the annual The discharge·weighted average of the discharge-weighted average concentrations of dissolved dissolved-solids concentrations at EI Paso during the solids usually range from 1,000 to 3,000 m9tl. 1930-68 period of record was about 800 mgtl. The Concentrations in single samples and monthly dissolved·solids concentrations vary seasonally. During composites often greatly exceed the annual averages. the spring and summer when water is released from the The highest dissolved-solids concentration in a monthly upstream reservoirs, the concentrations at EI Paso are composite was 10,700 mgtl in June 1953. usually about 600 or 700 mgtl, or only slightly higher than that of water released at the upstream dam. Water passing the Fort Quitman station usually is very hard, but the principal chemical constituents vary. In the fall and winter when no water is released Waters of low mineralization usually are of the calcium from the reservoirs, the flow at the EI Paso station is bicarbonate type; highly mineralized waters usually are from seepage and delayed return flows and usually of the sodium chloride type. The annual contains from 1,000 to 2,000 m9tl dissolved solids_ At discharge-weighted average concentration of chloride has times, the dissolved solids exceed 2,000 mgtl and has ranged from 21 mgtl in 1957 and 1965 to 1,640 mgtl in been as high as 3,830 mgt!. The water is very hard 1964. The discharge-weighted average concentration of (9reater than 180 mgtl). The principal cation in the sulfate has ranged from 45 mgtl in 1965 to 995 mgtl in water is sodium; the principal anion usually is sulfate, 1961. but in some of the more highly mineralized water, the percentage of chloride increases. During the period Since 1950, the water that has passed the station 1930-68, the concentration of sulfate in samples from at Fort Quitman seldom has reached the upper Presidio the EI Paso station ranged from less than 150 mgtl to station. Diversions, seepage into the permeable terrane, more than 1,250 mgtl; the discharge-weighted average and evapotranspiration probably consume most of the was 263 mgt!. The chloride concentration ranged from water. Since 1950, most of the water at upper Presidio less than 50 mgtl to more than 1,050 mgtl; the has been contributed by mountain creeks or arroyos that discharge-weighted average was 130 mgt!. join the Rio Grande in the stretch below Fort Quitman.

Most of the water passing the EI Paso station is Until 1945, the discharge-weighted averages of diverted by the American Canal in Texas and the dissolved solids for the upper Presidio station were Acequia-Madre in Mexico for irrigation and municipal approximately the same as those for the Fort Quitman use. Evaporation and leaching of salts from the soils station. Since then, and especially since 1950, the flow increase the salinity of the water used for irrigation. at Fort Quitman has been small; and the annual Return flows and drainage from the irrigated areas cause discharge-weighted averages of dissolved solids usually the residual water in the river downstream from the have been considerably greater than those for the upper diversion sites to become more mineralized. Presidio station (Figure 7).

In an inventory of Texas irrigation, Gillett and During the period from 1950 to 1968, the annual Janca (1965, p. 16) showed that not a single irrigated discharge-weighted averages of dissolved solids for the acre in EI Paso County in 1958 and 1965 depended on Fort Quitman station ranged from 294 to 4,440 mg/l surface water alone. Surface supplies were supplemented and averaged 2,120 mgt!. During this same period, the by wells, most of which are shallow and derive their annual discharge·weighted averages of dissolved solids water from the alluvium. The alluvium is supplied for the upper Presidio station ranged from 279 to 1,700 mostly from the percolation of excess irrigation water. mgtl and averaged 748 mgtI. Thus, the flow of the Rio Grande is recycled several times, and minerals in the water become extremely concentrated at the lower end of the EI Paso Valley. Middle Rio Grande Basin

During extended periods from 1951 to 1959, no Because three-fourths of the flow in the Rio flow was recorded at the station near Acala, Texas. Grande below EI Paso comes from the Mexican side, the During these periods, any irrigation returns and seepage quality of the inflows from Mexico is of major to the river in the reach below the station was diverted importance to the quality of water in the Rio Grande again and again until all was used before reaching the and the main stem reservoirs. station Rio Grande at Fort Quitman. During these

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Figure 7.-Discharge-Weighted Average of Dissolved Solids for the Rio Grande and Principal Inflow Stations

Downstream from the upper Presidio station, over was of the sodium sulfate or sodium calcium sulfate one-half million acre-feet of water a year is added to the type, flow of the Rio Grande by the Rio Conchas, the largest of the Mexican tributaries, to the middle reach of the Chemical analyses of samples from the two Rio Grande_ The chemical quality of water in the Rio stations usually did not include the determination of Conchos is shown in Figure 7_ Since 1850, when sulfate. However, the annual discharge-weighted averages complete use of upper Rio Grande waters in the EI Paso of the sulfate concentrations, as calculated from Valley began, the yearly discharge-weighted averages of available data for the period from 1950 to 1968, ranged dissolved solids of the water from the Rio Conchos near from 158 to 408 mg/l and averaged 291 mg/l for the Ojinaga, Mexico, very closely paralleled and at times station Rio Conchos near Ojinaga. The were almost identical to those of the Rio Grande at discharge-weighted averages of chloride for the station Johnson Ranch near Castolon, a hundred miles ranged from 26 to 96 mg/l and averaged 61 mg/l. During downstream. The discharge-weighted average this same period, the discharge-weighted average concentrations of dissolved solids for the period from concentrations of sulfate for the station Rio Grande at 1950 to 1968 for the two stations were identical, 728 Johnson Ranch near CastoIon ranged from 150 to 409 mg/1. Water at both stations was very hard and usually mg/l and averaged 290 mg/l, the discharge·weighted

·23· averages of chloride concentrations ranged from 24 to in Figure 7_ The quality of the Pecos River water is 91 m9tl and averaged 62 m9tl. considered in another section of this report.

Tributaries that drain from the Texas side of the The Devils River joins International Amistad basin and join the Rio Grande between the Rio Conchos Reservoir on the Rio Grande downstream from the and the station Rio Grande at Johnson Ranch near Pecos River. Water from Devils River near Juno and at CastoIon include Alamito and Terlingua Creeks. The Pafford Crossing near Comstock, Lake Walk, and Cantu dissolved-solids content of samples from Alamito Creek and San Felipe Springs contained less than 250 mgtl near Presidio, which probably is fairly representative of dissolved solids and were of the calcium bicarbonate water contributed by other mountain streams in the type, typical of the Edwards Plateau. area, ranged from 253 to 448 mgtl. The discharge-weighted concentrations of dissolved-solids for The only water of poor quality collected from the Alamito Creek near Presidio probably average about Del Rio area during the reconnaissance was from Eight 250 mgtl. The water usually is moderately hard or hard. Mile Creek near Del Rio where concentrations of Available data indicate that when the dissolved-solids dissolved solids ranged from 820 to 2,060 mgtl. The content exceeds about 300 mgtl, the water is of the source of the flow is a small spring and possibly a sodium bicarbonate type. However, water containing less flowing well in the area that may be connected to the than 300 m9tl dissolved solids probably is of the calcium creek through fractured limestone. The principal bicarbonate type. The chloride content of samples from constituents of this saline flow are calcium and sulfate. Alamito Creek ranged from 4.7 to 27 mgtl; the sulfate content ran9ed from 16 to 51 mgtl. Single samples from Chacon Creek near Laredo, Los Olmos Creek near Rio Grande City, and La Joya Water in Terlingua Creek is more mineralized than Creek near Samfordyce, which are Texas tributaries to that in Alamito Creek_ The dissolved-solids content of the Rio Grande, were all saline. The concentrations of samples from Terlingua Creek near Terlingua ranged dissolved solids were 4,420, 11,500, and 5,740 mgtl, from 400 to 1,140 mgtl. Most of the samples were respectively. Sodium and chloride were the predominant collected during low flow and contained more than constituents. 1,000 mgtl dissolved solids. However, the discharge-weighted concentrations of dissolved solids Tributaries that drain from the Mexican side of the probably average about 500 mgt!. Water in Terlingua basin and join the Rio Grande between International Creek usually is very hard and of the sodium calcium Amistad Reservoir and the station Rio Grande at Laredo sulfate type. The chloride content of samples from include Rio San Diego and Rio San Rodrigo. Water from Terlingua Creek ranged from 6.4 to 9.5 mgtl; the sulfate these streams usually contains less than 400 mgtl content ranged from 135 to 644 mgtl. dissolved solids, 30 mgtl chloride, and 75 mgtl sulfate. The water is hard or very hard and of the calcium Although no major tributaries join the main bicarbonate type. stream between the stations Rio Grande at Johnson Ranch near Castolon and Rio Grande at Foster Ranch The excellent quality of water from the Devils near Langtry, the annual inflow from small tributaries River and from small spring-fed streams on both sides of and springs in this reach averages more than 300,000 the Rio Grande more than compensate for the increased acre-feet. This inflow usually reduces the concentrations salinity caused by inflow from the Pecos River. The of dissolved solids and variations of chemical quality of discharge-weighted average concentrations of dissolved water in the Rio Grande. At no time during the period solids, chloride, and sulfate for the Rio Grande at of record has the dissolved solids in composite samples Laredo, Texas, during the 1956-68 period were 485 from the Rio Grande at Foster Ranch near Langtry mgtl, 81 mgtl, and 148 mgtl, respectively. exceeded 1,000 mgtl. During the period from 1944 to 1968, the range of annual discharge-weighted average The general improvement in the quality of water concentrations were as follows: dissolved solids, 449-699 in this reach of the Rio Grande occurs in spite of mgtl; chloride, 29-91 mgtl; and sulfate 161-269 mgtl. diversions of water by Maverick Canal for powerplant The water was very hard and usually of the sodium cooling and for irrigation and in spite of the subsequent calcium sulfate type. return of the water to the river. The amount of flow that returns to the river from the powerplant is essentially The next major contribution to the middle reach undiminished; thus, the concentration of salts by of the Rio Grande is the saline flow from the Pecos evaporation is small. Water from the Maverick Canal is River. The dissolved-solids discharge-weighted average used to irrigate about 35,000 acres above and below for the Pecos River near Langtry, just before it joins the Eagle Pass_ The amount of water returning to the river is Rio Grande, was 1,460 m9tl during the period 1955-68. large and the concentration of salts by leaching and During this same period, the discharge-weighted average evaporation is small. Although considerable quantities of concentration of dissolved solids upstream at the Rio water are diverted, the gain in flow of the Rio Grande Grande at Foster Ranch near Langtry was 581 mgtl. The between International Amistad Dam and Laredo variations in salinity of the Pecos River inflow is shown averages more than 350,000 acre-feet per year.

·24 - Lower Rio Grande Basin Pecos River Subbasi n

Flow of the Rio Grande in the lower basin is Water in the Pecos River usually is very saline as it impounded in International Falcon Reservoir. The Rio enters Texas. In a short reach of about 3 miles in the Salado, in Mexico, also contributes water to Malaga Bend of the river in southern Eddy County in International Falcon Reservoir. Although the Rio Salado New Mexico, about 420 tons of dissolved minerals, at Las Tortillas has contained as much as 5,000 mgtl mostly sodium chloride, is added daily to the mineral dissolved solids, the discharge-weighted average for the load of the river. The source of the salt is a concentrated station during the period from 1955 to 1968 was 522 brine that percolates upward from an aquifer that mg/1. During the period from 1956 to 1968, the underlies the area. An experimental salinity-alleviation discharge-weighted average concentrations of dissolved project has been in operation at Malaga Bend since solids, chloride, and sulfate for the Rio Grande below August 1963. Brine is being pumped from a well into an International Falcon Dam were 493 mg/I, 84 mg/I, and evaporation basin to lower the water level in the brine 150 mgtl, respectively. The water is very hard and aquifer and thus prevent its seepage into the river. The usually is of the mixed type in which no cation or anion results of the project are still being evaluated. predominates. The Pecos River receives water of better quality Releases from International Falcon Reservoir from the Delaware River but the amount is too small to provide most of the water used for municipal supply, reduce the salinity significantly. When sampled in irrigation, and industrial use in the Lower Rio Grande August 1966, the Delaware River near Red Bluff, New Valley. However, since 1943, Marte R. Gomez Reservoir Mexico, contained 1,980 mg/I dissolved solids, 8.8 mg/I on the Rio San Juan in Mexico has provided chloride, and 1,300 mg/l sulfate. The water was very considerable quantities of water for irrigation in the hard and was of the calcium sulfate type. reach from Ciudad Miguel Aleman, Mexico (near Roma, Texas) to Rio Bravo, Mexico (near Mercedes, Texas). Since 1937, the flow of the Pecos River has been Some of the water used for irrigation drains back into impounded in Red Bluff Reservoir. The chemical quality the Rio San Juan before it joins the Rio Grande; but of the outflow from the reservoir has been monitored at most of the return flows enter the Rio Grande through the daily sampling station Pecos River below Red Bluff five drains~the Rancherias and Los Fresnos drains Dam near Orla or 15 miles downstream at the gaging upstream from Fort Ringgold, Texas, and the Los station, Pecos River near Orla. During some periods, the Puerteoitos, Huizache, and Morillo drains downstream quality of the water at the station near Orla is impaired from Fort Ringgold. Water contributed to the Rio by saline inflow from Salt (Screwbean) Draw. Therefore, Grande by the Rio San Juan and these five drains is records for the station Pecos River below Red Bluff Dam saline most of the time. The concentration of dissolved near Orla are more representative of the chemical quality solids in Morillo drain averages about 10,000 mg/I, which of outflow from the reservoir. is several times greater than the average concentration in the other drains. To supplement chemical-quality records for outflow from Red Bluff Reservoir and to determine the Inflow of saline vvater from these sources has areal variations of the quality of water in the reservoir, caused an increase in the dissolved·solids content of the the Geological Survey in cooperation with the Red Bluff Rio Grande. During the 1959·68 period, the Water Power Control District conducted a series of discharge-weighted average concentration of dissolved water-quality surveys during the period from 1965 to sol ids for the station Rio Grande at Anzalduas Dam was 1968 (Kunze and Rawson, 1970). During each of the 684 mg/1. Although this concentration would not be surveys, water throughout the reservoir was saline. excessive in water used for irrigation in other areas, it However, during same periods, water at the surface was may adversely affect crop production in the Lower Rio much less saline than that at the bottom. For example, Grande Valley where the mineral content of the soil is on October 12, 1965, the concentration of dissolved high and where leaching of the minerals is restricted solids at a deep site near Red Bluff Dam ranged from because of the high water table, tight structure of the 4,260 mg/I at the surface to 10,200 mgll at a depth of soil, and flat topography. 38 feet. Thus, selected withdrawal of the more saline water from the reservoir during non-irrigating periods As a measure to improve the quality of the water would improve the quality of the water available for in the Lower Rio Grande Valley, the saline water from irrigation. the Morillo drain has recently been diverted through a 75-mile long channel to the Gulf of Mexico. Preliminary Evaporation, irrigation returns, and the inflow of results indicate that diversion of the saline water has highly mineralized ground water or brines from oil fields caused a significant improvement of the quality of the usually cause a progressive increase of dissolved solids water in the Rio Grande. and chloride in the Pecos River between the chemical·quality stations below Red Bluff Dam near

·25· Orla and at Girvin (Figure 8). Inflow of ground water The concentration of dissolved solids in irrigation downstream from this reach usually results in a returns to the Pecos River through the Barstow drain reduction in the concentration of dissolved solids. range from about 7,000 to 9,000 mg/1. These irrigation During the period from 1961 to 1968, the returns are largely responsible for the progressive discharge-weighted average concentrations of dissolved increase of the concentration of dissolved solids in the solids for the stations Pecos River below Red Bluff Dam, Pecos River between Orla and Girvin. at Girvin, and at Shumla (now near Langtry) were 7,770 mg/I, 14,200 mg/I, and 1,600 mg/I, respectively. The Water samples collected from Phantom Lake discharge-weighted average concentrations of chloride Springs and San Solomon Springs near Toyahvale and were 3,080 mg/I, 5,820 mg/I, and 572 mg/I, and those of from Lake Balmorhea at Balmorhea generally contained sulfate were 1,880 mg/I, 3,370 mg/I, and 324 mg/1. more than 2,000 mg/l dissolved solids, 600 mg/I Water at each of the sites was very hard and of the chloride, and 600 mg/I sulfate. sodium chloride type. Water-delivery and low-flow studies (Grozier and others, 1966 and 1968; Spiers and Analyses of samples from Toyah Creek near Pecos Hejl, 1970) generally have documented the increase of and Salt Draw near Pecos show both of these inflows to dissolved solids in the Pecos River between Red Bluff Toyah Lake to be saline, ranging from about 5,000 to Dam and Girvin and the reduction thereafter. 14,000 mg/I dissolved solids. However, the water of Limpia Creek above and below Fort Davis, is of excellent quality (less than 250 mg/I dissolved solids, 10 mg/I chloride, and 30 mg/I sulfate). The water at the site llISS0,,-VEO SO~IDS J. I /\ above Fort Davis is soft to moderately hard; below Fort i J ;' c_ ---~' Davis the water is moderately hard to hard. Water at ~,,-- both sites is of the calcium bicarbonate type. / I II Toyah Lake overflows infrequently into the Pecos f/ -]\ / A V'-. \ River through lower Toyah Creek. These overflows are 1/\ /\ I usually very saline because of the concentration of the 1/ v saline inflows by evaporation. A / ~/ / V Water from Coyanosa Draw near Fort Stockton, V when sampled in 1965 and 1967, contained less than

C~LORIDE 250 mg/I dissolved solids, 5 mg/I chloride, and 30 mg/l ," \ sulfate and was moderately hard or hard. Some of the I , ~ I r \ .J '}-..-/ water from Coyanosa Draw is diverted for irrigation, but , , \/ - A most of it goes to ground-water recharge. Therefore, \/1 \ only at times of extreme floods does flow from the draw /\ , 1/\ " vi / V"- reach the Pecos River. 0 N, \ /\ / ~ Inflow to the middle Pecos River from Live Oak I~ v Creek near Old Fort Lancaster was moderately saline " V\ J Iv I (4,610 mg/I dissolved solids) at the time of sampling. - ~, - "' ," .. -_"'" '''~''''._ 0." "- _c<~._e..-.~ -- ...,.. ',m ,_ -=-_....., 00. "'" __~~'"'' •••• ~ ...... ""..

RELATION OF CHEMICAL Figure 8.-Dis<:harge-Weighted Average of Chloride QUALITY TO USE and Dissolved Solids for the Pecos River Below Red Bluff Dam Near Orla. Below Grand Falls, and at Girvin The early studies of the water resources of the western United States dealt heavily on the quantity and not the quality of water. Early irrigation developments Three miles below Red Bluff Reservoir, low flows on the Pecos River were to a large extent failures from Salt (Screwbean) Draw entering the Pecos River are very saline. When sampled in 1947 and 1948, the stream because the chemical quality of the water was not usually contained more than 15,000 mg/I dissolved considered in the application of irrigation waters. solids, 7,000 mg/I chloride, and 3,000 mg/I sulfate. The However, during the last few decades, water·quality water was very hard and of the sodium chloride type. criteria for specific uses have been established, and water Infrequent flood inflows probably are of better quality treatment for specific uses has become a science. than that of the river. The usual flow of Salt (Screwbean) Draw is less than one cfs (cubic foot per second) and the stream is dry for long periods. Thus, the salt contributions to the Pecos River by Salt (Screwbean) Draw are not a major problem.

- 26· Domestic Purposes However, water from several streams or springs including Alamito, Terlingua, and Limpia Creeks, and Phantom Because of differences in individuals, the varying Lake and San Solomon Springs often contain more than amounts of water they use, and other factors, definition 1.0 mg/I fluoride. of the safe limits of the mineral constituents in water is difficult. The criteria usually accepted in the United Most surface waters in the Rio Grande basin are States are those established by the United States Public hard or very hard and should be softened if used for Health Service. Since 1914, these standards have been domestic purposes. used to control the qual ity of the water used by interstate carriers for drinking and culinary purposes. The concentrations of dissolved solids and sulfate The widespread use of the standards and technological in the Rio Grande upstream from the Rio Conchos advances since 1914 have led to a series of revisions, the usually exceed the limits recommended by the U.S. latest of which was in 1962 (U.S. Public Health Service, Public Health Service; the chloride concentration often 1962). The standards have been accepted by the exceeds the recommended limit. However, the inflow of American Waterworks Association and by most state less mineralized water from the Rio Conchas and other departments of public health as minimum standards for tributaries and springs in the middle reach of the basin all public water supplies. reduces the concentrations of dissolved constituents in the main stem. Thus, the concentrations of dissolved The limits specified by these standards for various solids, chloride, and sulfate in the lower reach of the Rio constituents are included in the statements under Grande usually are within the recommended limits. "Significance" in Table 2. Although the recommended limits for dissolved solids, chloride, and sulfate are 500 Water in the Rio Conchos, though of better mg/I, 250 mg/I, and 250 mg/I, respectively, a quality than that in the upstream reach of the Rio considerable number of water supplies exceeding these Grande, usually contains more than the recommended recommended limits have been used for domestic limits of dissolved solids and sulfate. purposes without noticeable adverse effects. Water in the Pecos River and some of its Concentrations of fluoride within a desirable tributaries is more saline than that in the Rio Grande concentration range is beneficial to sound teeth. and usually is undesirable for domestic use because of However, excessive concentrations may cause mottling excessive concentrations of dissolved solids, chloride, or of teeth enamel. According to the U.S. Public Health sulfate. Service Drinking Water Standards, the concentration of fluoride should not average more than the appropriate The quality of the water in other tributaries to the upper limit in the following table: middle and lower reaches of the Rio Grande generally is superior to that of the Pecos River. The concentrations U.s. PUBLIC HEALTH SERVICE of dissolved solids, chloride, and sulfate in most of these ANNUAL AVERAGE RECOMMENDED CONTROL streams usually are not excessive. However, low flows in OF MAXIMUM LIMITS (FLUORIDE Eight Mile, Chacon, Los Olmos, and La Joya Creeks DAILY AIR CONCENTRATIONS IN MG/Ll contain more than the recommended limits of dissolved TEMPERATURES ("FlY LOWER OPTIMUM UPPER solids, chloride, and sulfate. 50.0-53.7 0.9 1.2 1.7 Nitrate concentrations in surface waters in the Rio 53.8·58.3 .8 1.1 1.5 Grande basin usually are considerably less than the 45 58.4·63.8 .8 1.0 1.3 mg/I limit recommended by the U.S. Public Health Service. Surface water throughout the basin seldom 63.9-70.6 .7 .9 1.2 contains more than 5 mg/I nitrate and often contains less 70.7·79.2 .7 .8 1.0 than 1 mg/I. 79.3-90.5 .. .7 .8 Although iron determinations usually have not lISased on temperature data obtained for a minimum of 5 been included in chemical analyses of surface water from years. the Rio Grande basin, analyses of ground water in the basin (Davis and others, 1965) and analyses of surface On the basis of temperature data for EI Paso, Del waters at selected sites on the Rio Grande and Pecos Rio, and Brownsville, the maximum daily air River indicate that the concentration of iron in surface temperatures average about 77°F (2SoC) in the upper waters of the basin usually is less than the 0.3 mg/llimit Rio Grande basin and about 83°F (28°C) in the middle recommended by the U.S. Public Health Service. and lower basin. Thus, the fluoride content of drinking water should not exceed 1.0 mg/I in the upper basin and 0.8 mg/I in the middle and lower basin. The fluoride Industrial Use content of water in the Rio Grande and most of the principal tributaries usually is less than 0.8 mg/1. The quality requirements for industrial water vary widely (See Table 3). For some purposes such as cooling,

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-28 - water of almost any quality can be used; for other water to cause a concentration of salts in the soil is purposes, such as use in high· pressure boilers, the water called the salinity hazard of the water. The specific must exceed the quality of commercial distilled water. conductance of the water is used as an index of the salinity hazard. Excessive hardness of water for industrial supplies is usually objectionable because it causes the formation High concentrations of sodium relative to the of scale in boilers, pipes, water heaters, and cooling concentrations of calcium and magnesium in irrigation jackets. When excessive scale forms, heat transfer water can adversely affect soil structure. Cations in the capacity is lost, flow is restricted, and eventually soil solution become fixed on the surface of the soil equipment failure occurs. Hovvever, some hardness particles; calcium and magnesium tend to flocculate the usually is desirable because it forms a protective coating particles, whereas sodium tends to deflocculate them. in pipes and equipment and reduces corrosion. This adverse effect on soil structure caused by high sodium concentrations in an irrigation water is called the High dissolved-solids concentrations increase the sodium hazard of the water. An index used for corrosive properties of water, particularly if chloride is predicting the sodium hazard is the sodium·adsorption the predominant ion. When both magnesium and ratio (SARI. which is defined by the equation: chloride concentrations are high, the corrosiveness is increased. Na+ SAR- ;:::::;;:::;::;:=;:;;:::;::;: Most surface waters in the Rio Grande basin are ~ ca++;M9++ hard or very hard and will require sohening for some industrial applications.

During some periods, water in the Rio Grande where the concentration of the ions are expressed in upstream from Fort Quitman is slightly saline. Water in milliequivalents per liter. the Pecos River and some of its tributaries are slightly to very saline. Thus, water in these streams is of poor The U.S. Salinity Laboratory Staff (1954) quality for some industrial uses. Water in most of the prepared a classification for irrigation waters in terms of other streams is suitable for many industrial uses or can salinity and sodium hazards. Empirical equations were be made suitable with a minimum of treatment. used in developing a diagram, reproduced in modified form as Figure 9, which uses SAR and specific conductance in classifying irrigation waters. This Irrigation classification, although embodying both research and field observations, should be used only for general The suitability of water for irrigation depends guidance because many additional factors (such as primarily on its chemical composition. Hovvever, the availability of water for leaching. ratio of applied water extent to which chemical quality limits the suitability of to precipitation, and crops grown) affect the suitability a water for irrigation depends on many factors, such as: of water for irrigation. With respect to salinity and the nature, composition, and drainage of the soil and sodium hazards, waters are divided into four subsoil; the amount of water used and the method of classes-low, medium, high, and very high. The application; the control of evaporation; the kind of classification range encompasses those waters that can be crops grown; and the climate of the region, including the used for irrigation of most crops on most soils as well as amounts and distribution of rainfall. Because these those waters that are usually unsuitable for irrigation. factors are highly variable. every method of classifying Selection of class demarcation is discussed in detail in waters for irrigation is somewhat arbitrary. the publication by the U.S. Salinity Laboratory Staff. Interpretation of the diagram is as follows: According to the U.S. Salinity Laboratory Staff (1954. p_ 691. the most important characteristics in "Low-Salinity Water (ell can be used for determining the quality of irrigation water are: (1) total irrigation with most crops on most soils with little concentration of soluble salts, (2) relative proportions of likelihood that soil salinity will develop. Some leaching sodium to other cations, (3) concentration of boron or is required, but this occurs under normal irrigation other elements that may be toxic, and (4) excess of practices except in soils of extremely low permeability." milliequivalents of bicarbonate over milliequivalents of calcium plus magnesium. "Medium·Salinity Water (C2) can be used if a moderate amount of leaching occurs. Plants with High concentrations of dissolved salts in irrigation moderate salt tolerance can be grown in most cases water may cause a buildup of salts in the soil solution without special practices for salinity control." and may make the soil saline. The increased soil salinity may reduce crop yields drastically by decreasing the "High-Salinity Water (C3) cannot be used on soils ability of the plants to take up water and essential plant with restricted drainage. Even with adequate drainage, nutrients from the soil solution.This tendency of irrigation special management for salinity control may be required and plants with good salt tolerance should be selected."

·29· SPECIFIC CONDUCTANCE, IN MiCRO MHOS AT 25·C except that amendments may not be feasible with waters of very high salinity." '00 2 34 5678QOO 2345000,, ~~ , " ... '0 6. Alamita Creek near Presidia, PresidIO Co., Te 30 ~ . o Phantom Lake $prir.gs near Toyahvale, "Very High Sodium Water (54) is generally 2. Reeves Co. o DeVIls River near Del Rio unsatisfactory for irrigation purposes except at low and 26 perhaps medium salinity. where the solution of calcium from the sailor use of gypsum or other amendments , n '4 - ~ may make the use of these waters feasible." 22

Q c 20 20 To relate the quality of basin waters to the U.S. ~ ~ ~ N• Salinity Laboratory Staff's classification for irrigation •X z,· Q waters, the sodium and salinity hazards were calculated ~ ~ for key stations with concurrent records from 1960 to ! N &: 16 , ~ 0 3 ~ 1968. :! ~ 14 •~ ~ 12 Data in Table 4 show that the salinity hazard of ~ 15 0 water throughout the Rio Grande usually is high; ~IO 10 whereas the salinity hazard of the Pecos River below • o Red Bluff Dam near Drla is very high . ; - 6 ~ The sodium hazard usually ranges from low to 4 medium at the Rio Grande stations but is very high at the Pecos River below Red Bluff Dam near Drla. Thus, 2 o the long term use of water from the Rio Grande and Pecos River for irrigation will require special soil management, good drainage, high leaching, and selection of salt-tolerant crops.

SALINITY HAZARD Irrigation water from the Devils River near Del Rio and Alamito Creek near Presidio would be classified as

Figure g.-Classification of Irrigation Waters having a medium salinity hazard and a low sodium hazard. Water from Phantom Lake Springs near Toyahvale would be classified as having a very high .. Very High Salinity Water (C4) is not suitable for salinity hazard and a medium sodium hazard (Figure 9). irrigation under ordinary conditions, but may be used occasionally under very special circumstances. The soils The boron concentrations in samples from the Rio must be permeable, drainage must be adequate, Grande are less than 1 mg/l and usually are less then irrigation water must be applied in excess to provide 0.67 mg/I (Table 51. Thus, the use of the water from the considerable leaching, and very salt-tolerant crops should Rio Grande for irrigation presents little likelihood of be selected." boron damage. Less tolerant crops might suffer some damage from boron in the EI Paso area, but the "Low-Sodium Water (51) can be used for likelihood of damage in the middle and lower valley is irrigation on almost all soils with little danger of the remote because of dilution from rainfall. All samples development of harmful levels of exchangeable sodium. from the Pecos River at Shumla contained less than 0.33 However, sodium-sensitive crops such as stone-fruit trees mg/l boron. Thus, this water can be used on most crops may accumulate injurious concentrations of sodium." with little likelihood of boron damage.

"Medium-Sodium Water (52) will present an appreciable sodium hazard in fine-textured soils having SUMMARY high cation-exchange capacity, especially under low· leaching conditions, unless gypsum is present in the Surface water in the Rio Grande basin ranges from soil. This water may be used on coarse-textured or fresh to very saline. Principal factors that determine the organic soils with good permeability." chemical quality include geology and irrigation return flows. "High-Sodium Waters (S3) may produce harmful levels of exchangeable sodium in most soils and will The upper reaches of both the Rio Grande and the require special soil management-good drainage, high Pecos River in Texas traverse deposits of Quaternary age. leaching, and organic-matter additions. Gypsiferous soils During fall and winter when the flow consists principally may not develop harmful levels of exchangeable sodium of seepage from the Quaternary deposits and delayed from such waters. Chemical amendments may be return flow from irrigation, water in the Rio Grande at required for replacement of exchangeable sodium, EI Paso usually contains from 1,000 to 2,000 mg/I

·30 - Table 4.-Sodium and Salinity Hazards of Monthly Samples at Selected Sites in the Rio Grande Basin, 1960.68

PERCENTAGE OF SAMPLES SODIUM HAZARD SALINITY HAZARD VERY VERY STATION LOW MEDIUM HIGH HIGH LOW MEDIUM HIGH HIGH

Aio Grande at El Paso, Texas 54 35 5 6 0 2 62 36 Pecos River below Red Bluff Dam near Orla, Texas 0 0 4 96 0 0 0 100

Rio Grande at Laredo, Texas 100 0 0 0 0 16 84 0

Rio Grande at Anzalduas Dam, Texas 85 15 0 0 0 4 96 0

Table 5.-Boron Concentrations in Monthly Samples at Selected Stations in the Rio Grande Basin, 1960-68

PE RCENTAG E OF SAMPLES CONCENTRATION OF RIO GRANDE RIO GRANDE AT PECOS RIVER BORON IN MG/L AT EL PASO ANZALDUAS DAM AT SHUMLA

More than 0.33 68 43 99

More than 0.33; less than 0.67 26 53

More than 0.67; less than 1.00 6 4 0 dissolved solids. During the spring and summer when usually is moderately or very saline, very hard, and of water is released from reservoirs in New Mexico, the the sodium chloride type. During the period from 1961 dissolved-solids concentrations usually range from 600 to 1968, the discharge-weighted average concentrations to 700 mg/1. The water is very hard. The principal cation of dissolved solids, chloride, and sulfate for the Pecos in the water is sodium; the principal anion usually is River below Red Bluff Dam near Orla were 7,770 mgtl, sulfate, but in some of the more highly mineralized 3,080 mgtl, and 1,880 mgtl, respectively. Evaporation, water, the percentage of chloride increases. The irrigation returns, and the inflow of highly mineralized discharge-weighted average concentrations of dissolved ground water cause an increase in the concentrations solids, chloride, and sulfate in the Rio Grande at EI Paso of dissolved solids in the reach of the Pecos during the 1930-68 period of record were about 800 River between the stations near Orla and at Girvin. mg/l, 130 mgtl, and 263 mgtl, respectively. However, inflow downstream from this reach usually results in a reduction of dissolved solids and chloride. Most of the water that passes the EI Paso station is During the 1961·68 period, the discharge-weighted diverted for irrigation and municipal use. Return flows average concentrations of dissolved solids, chloride, and from irrigation cause an increase in the salinity sulfate for the Pecos River at Shumla were 1,600 mgtl, downstream from the diversion sites. When a substantial 572 mgtl, and 324 m9tl, respectively. part of the annual flow of the Rio Grande at Fort Quitman is irrigation return flow, the annual Extensive deposits of Tertiary age crop out in the discharge-weighted average concentrations of dissolved upper, middle, and lower reaches of the Mexican side of solids usually range from 1,000 to 3,000 mgtl. During the Rio Grande basin and in the lower reach of the 1956, 1957, and 1965 when most of the water consisted Texas side. Water in the Rio Conchas, the principal of local runoff downstream from the irrigated areas, the tributary that traverses rocks of Tertiary age on the discharge-weighted average concentrations of dissolved Mexican side of the basin, usually is fresh, very hard, and solids for the Rio Grande at Fort Quitman were 375 of the sodium calcium sulfate type. The mg/l, 294 mgtl, and 375 mg/l. respectively. Water discharge-weighted average concentrations of dissolved passing the Fort Quitman station usually is very hard, solids, chloride, and sulfate for the Rio Conchos near but the principal chemical constituents vary. Waters of Ojinaga during the period from 1950 to 1968 were 728 low mineralization usually are of the calcium mg/l, 61 mgtl, and 291 mg/l. The Rio Conchos bicarbonate type; highly mineralized waters usually are contributes more than one-half million acre-feet of water of the sodium chloride type. a year to the Rio Grande. Thus, the quality of water in the Rio Grande downstream from the Rio Conchas is Water in the upper reach of the Pecos River in very similar to that of the Rio Conchas. During the Texas, which traverses deposits of Quaternary age, period from 1950 to 1968, the discharge-weighted

- 31 - average concentrations for the Rio Grande at Johnson constituents_ Thus, the concentrations of dissolved Ranch near Castolon, 100 miles downstream from the solids, chloride, and sulfate are within the recommended Rio Conchos, were: dissolved solids, 728 mg!l; chloride, limits from the confluence with the Rio Conchas to the 62 mgtl; and sulfate, 290 mgtl. vicinity of Rio Grande City, where saline drains reach the Rio Grande. Much of the middle reach of the Rio Grande basin is underlain by rocks of Cretaceous age. Streams that Water in the Pecos River and some of its traverse these outcrops include Devils River, San Felipe tributaries usually is undesirable for domestic use Creek, Rio San Diego, and Rio San Rodrigo. Water in because of excessive concentrations of dissolved solids, the streams usually is fresh, hard, and of the calcium chloride, and sulfate. The Quality of the water in other bicarbonate type. tributaries to the middle and lower reaches of the Rio Grande generally is superior to that of the Pecos River. Water from these streams and inflow from springs The concentrations of dissolved solids, chloride, and reduce the concentrations of dissolved solids and sulfate in these tributaries usually are not excessive for variations of chemical quality of water in the middle domestic use. reach of the Rio Grande. During the 1956-68 period, the discharge-weighted concentrations of dissolved solids, Nitrate concentrations in surface waters in the Rio chloride, and sulfate for the Rio Grande at Laredo were Grande basin usually are considerably less than the 45 485 mgtl, 81 mgtl. and 148 mgtl, respectively. mg!1 limit recommended by the U.S. Public Health Service. The fluoride content of the Rio Grande and Flow of the lovver Rio Grande is impounded in most of the principal tributaries usually is less than 0.8 International Falcon Reservoir. Releases from mgt!. International Falcon Reservoir provide most of the water for irrigation and municipal and industrial supplies Most surface waters in the basin are hard or very in the Lovver Rio Grande Valley. During the period from hard and will require softening for some industrial 1956 to 1968, the discharge-weighted average applications. During some periods, water in the Rio concentrations of dissolved solids, chloride, and sulfate Grande upstream from Fort Quitman is slightly saline. for the Rio Grande below Falcon Dam were 493 mg!l, Water in the Pecos River and some of its tributaries are 84 mgtl. and 150 mgtl. respectively. Return flows from slightly to very saline. Thus, water in these streams is of irrigation and other saline inflows have increased the poor Quality for some industrial uses. Water in most of concentrations of dissolved constituents in the lower Rio the other streams is suitable for many industrial uses. Grande, and during the 1959-68 period. the discharge-weighted average concentration of dissolved The principal use of surface water in the Rio solids at Anzalduas Dam was 684 mgtl. Grande basin is irrigation. The salinity hazard of water throughout the Rio Grande usually is high; that of the The concentrations of dissolved solids and sulfate Pecos River below Red Bluff Dam is very high. The in the Rio Grande upstream from the Rio Conchos sodium hazard of water in the Rio Grande usually ranges usually exceed the U.S. Public Health Service from low to medium; that of the Pecos River usually is recommended limits for drinking water. However, the very high. Thus, the long-term use of water from the Rio inflow of less mineralized water from the Rio Conchos Grande and Pecos River for irrigation will require special and other tributaries and springs in the middle reach of soil management, good drainage, high leaching, and the basin reduces the concentrations of dissolved selection of salt-tolerant crops.

- 32- REFERENCES CITED

American Water Works Association, 1950, Water quality Hughes, l. 5., and Rawson, Jack, 1966, Reconnaissance and treatment: Am. Water Works Assoc. Manual, 2d of the chemical quality of surface waters of the San ed., tables 3·4, p. 66·67. Jacinto River basin, Texas: Texas Water Devel. Board Rept. 13, 45 p., 11 figs., 2 pis. Blakey, J. F., and Kunze, H. L., 1971, Reconnaissance of the chemical quality of surface waters of the Kunze, H. l., 1969, Reconnaissance of the chemical coastal basins of Texas: Texas Water Devel. Board quality of surface waters of the Lavaca River basin, Rept. 130, 49 p., 15 figs. Texas: Texas Water Devel. Board Rept. 92, 23 p., 9 figs. Carr, J. T., Jr., 1967, The climate and physiography of Texas: Texas Water Devel. Board Repe 53, 27 p., 8 __1971, Reconnaissance of the chemical quality of figs. surface waters of the Nueces River basin, Texas: Texas Water Devel. Board Repe 134,34 p., 8 figs. Comit~ de la Carta Geologica de Mexico, 1968, Carta geol6gica de la Rep~blica Mexicana: Ciudad Kunze, H. l., and Lee, J. N., 1967, Reconnaissance of Universitaria, M~xico. D. F", Mexico, 1 sheet. the chemical quality of surface waters of the Canadian River basin, Texas: Texas Water Devel. Davis, M. E., and others, 1965, Reconnaissance Board Repe 68, 29 p., 9 figs. investigations of the ground·water resources of the Rio Grande basin, Texas: Texas Water Camm. Bull. Kunze, H. l., and Rawson, Jack, 1970, Water-quality 6502,213 p. records for Red Bluff Reservoir, Texas and New Mexico, October 1965·August 1968: U.S. Geological Dowell, C. L, and Breeding, S. D., 1967, Dams and Survey open·file rept., 21 p., 1 fig. reservoirs in Texas, historical and descriptive information, December 31, 1966: Texas Water Devel. Leifeste, D. K., 1968, Reconnaissance of the chemical Board Rept. 48, 267 p., 1 pI. quality of surface waters of the Sulphur River and Cypress Creek basins, Texas: Texas Water Devel. Fenneman, N. M., 1931, Physiography of western Board Rept. 87, 34 p., 13 figs. United States: New York, McGraw-Hili Book Co., 534 p. Leifeste, D. K., Blakey, J. F., and Hughes, L. S., 1971, Reconnaissance of the chemical quality of surface Gillett, P. T., and Janca, I. G., 1965, Inventory of Texas waters of the Red River basin, Texas: Texas Water irrigation 1958 and 1964: Texas Water Comm. Bull. Devel. Board Repe 129, 72 p., 14 figs. 6515,317 p., 6 pis. Leifeste, D. K., and Hughes, L. 5.,1967, Reconnaissance Grazier, R. U., Albert, H. W., Blakey, J. F., and of the chemical quality of surface waters of the Hembree, C. H., 1966, Water-delivery and low·flow Trinity River basin, Texas: Texas Water Devel. Board studies, Pecos River, Texas, quantity and quality, Repl. 67, 65 p., 12 figs. 1964 and 1965: Texas Water Devel. Board Rept. 22, 21 p., 6 figs., 2 pis. Leifeste, D. K., and Lansford, M. W., 1968, Reconnaissance of the chemical quality of surface Grazier, R. U., Hejl, H. R., Jr., and Hembree, C. H., waters of the Colorado River basin, Texas: Texas 1968, Water-delivery study, Pecos River, Texas, Water Devel. Board Rept. 71, 82 p., 13 figs. quantity and quality, 1967: Texas Water Devel. Board Rept. 76, 16 p., 6 figs. Maier, F. J., 1950, Fluoridation of public water supplies: Jour. Am. Water Works Assoc., v. 42, pt. 1, Hughes, L. 5., and Leifeste, D. K., 1965, Reconnaissance p.1120·1132. of the chemical quality of surface waters of the Sabine River basin, Texas and Louisiana: U.S. Geo!. Maxwell, R. A., and others, 1967, Geology of Big Bend Survey Water·Supply Paper 1809·H, 71 p., 14 figs., National Park, Brewster County, Texas: Univ. Texas 1 pI. Pub. 6711, 320 p., 152 figs., 11 pis.

___1967, Reconnaissance of the chemical quality of National Resources Planning Board, 1942, Pecos River surface waters of the Neches River basin, Texas: U.S. Joint Investigation- Reports of the participating Geol. Survey Water·Supply Paper 1839·A, 63 p., 9 agencies: Washington, U.S. Govt. Printing Office, figs.,4 pis. 407 p.

·33· Oetking, P. F., and Feray, D. E. [compilers], 1963, U.S. Geological Survey, 1964b, Surface water records of Geologic Highway Map of Texas: Dallas Geo!. Soc. Texas, 1964: U.S. Geo!. Survey open·file rept. map, Dallas, Texas. __1964c, Water Quality records in Texas, 1964: U.S. Rawson, Jack, 1967, Study and interpretation of Geol. Survey open-file rept. chemical quality of surface waters in the Brazos River basin, Texas: Texas Water Devel. Board Rep!. 55, __1965a, Water resources data for Texas, 1965, 113 p., 10 figs. Part 1, Surface water records: U.S. Geo!. Survey open-file rept. __1968. Reconnaissance of the chemical quality of surface waters of the Guadalupe River basin, Texas: __1965b, Water resources data for Texas, 1965, Texas Water Devel. Board Rept. BB, 38 p., 11 figs. Part 2, Water quality records: U.S. Geo!. Survey open-file rept. __1969, Reconnaissance of chemical quality of surface waters of the San Antonio River basin, Texas: __1966a, Water resources data for Texas, 1966, Texas Water Devel. Board Rept. 93,26 p., 9 figs. Part 1, Surface water records: U.S. Geo!. Survey open-file rept. Spiers, V. L., and Hejl, H. R., Jr., 1970, Quantity and quality of low flow in the Pecos River below Girvin, __1966b, Water resources data fOf Texas, 1966, Texas, February 6·9, 1968: Texas Water Deve!. Board Part 2, Water quality records: U.S. Geo!. Survey Rept. 107, 13 p., 2 figs. open-file rept.

Stiff, H. A., Jr., 1951, The interpretation of chemical __1967a, Water resources data for Texas, 1967, water analysis by means of patterns: Jour. of Part 1, Surface water records: U.S. Geo!. Survey Petroleum Technology. Oct., p. 15. open-file rept.

Texas Board of Water Engineers, 1958, Compilation of ___1967b, Water resources data for Texas, 1967, surface water records in Texas through September Part 2, Water quality records: U.S. Geo!. Survey 1967: Texas Board Water Engineers Bull. 5807·A, open-file rept. 503 p., 4 pis. ___1968, Water resources data for Texas, 1968, Texas Water Development Board, 1968, The Texas Part 1, Surface water records: U.S. Geo!. Survey Water Plan: Texas Water Devel. Board planning rept., open-file rept. 228 p., 37 figs., 4 pis. U.S. Public Health Service, 1962, Drinking water Thornthwaite, C. W., 1952, Evapotranspiration in the standards, 1962: U.S. Public Health Service Pub. 956, hydrologic cycle, in The physical basis of water 61 p. supply and its principal uses, v. 2 of The Physical and Economic Foundation of Natural Resources: U.S. U.S. Salinity Laboratory Staff, 1954, Diagnosis and Congo, House Comm. on Interior and Insular Affairs, improvement of saline and alkali soils: U.S. Dept. of p.25-35. Agriculture Handb. 60, 160 p.

U.S. Geological Survey, 1960, Compilation of records of Vlissides, S. D., 1964, Oil and gas investigations: U.S. surface waters of the United States through Geol. Survey Map OM-214. September 1950, Part 8, Western Gulf of Mexico basins: U.S. Geol. Survey Water-Supply Paper 1312, Wood, L. A., Gabrysch, R. K., and Marvin, Richard, 633 p., 2 figs., 1 pI. 1963, Reconnaissance investigation of the ground-water resources of the Gulf Coast region, ___1964a, Compilation of records of surface waters of Texas: Texas Water Comm. Bull. 6305, 114 p., the United States, October 1950 to September 1960, 18 figs.. 15 pis. Part 8, Western Gulf of Mexico basins: U.S. Geo!. Survey Water·Supply Paper 1732, 574 p., 2 figs., 1 pI.

·34· Quality-of-Water Records for the Rio Grande Basin Are Published in the Following Texas Water Development Board Reports (Including Reports Formerly Published by the Texas Water Commission and Texas Board of Water Engineers) and U.S. Geological Survey Water-Supply Papers:

U.S.G.S. U.S.G.S. WATER~SUPPLY WATER·SUPPLY WATER YEAR PAPER NO. T.W.D.S. REPORT NO. WATER YEAR PAPER NO. T.W.O.B. REPORT NO.

1942 950 . 1938·45 1953 1292 '1953

1943 970 '1938-45 1954 1352 '1954

1944 1022 '1938-45 1955 1402 '1955

1945 1030 . 1938-45 1956 1452 Bull. 5905

1946 1050 '1946 1957 1522 Bull. 5915

1947 1102 '1947 1958 1573 Bull. 6104

1948 1133 '1948 1959 1644 Bull. 6205

1949 1163 '1949 1960 1744 Bull. 6215

1950 1188 '1950 1961 1884 Bull. 6304

1951 1199 '1951 1962 1944 Bull. 6501

1952 1252 '1952 1963 1950 Report 7

. "ChemIcal ComposlllOn of Texas Surface Waters" was deSignated only by water year from 1938 through 1955.

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W~,.. Yo.. 192~ ~d • JAn_ 2(1. 1925 ...... ,,,. 1.90 Mloi .... Ar', a ...... "'" WUAt Yoa. 1921> Kul_. Jan. D. 1921>. .. .. 1400 1.~(I Aug. .. .. IIlnl_. n ...... • .. '00 ." lola,.,' "d. 1921 Kooxl...... hrt. 21. 1927...... noo 3. IJ IIln1.u",. reb. 24...... 00 " W~<.r".u,192H ",,01_. hb. I. 192H...... "00 lo61 lIinl_. Kay 2...... 00~ hr'. 18 ...... " W~tu. 1929 .. .. HOO 2.31 lIint ...... Aug. II...... 00 .~

Wain YOAT 193(1 ~ lIul .... Fob. 3. 1930.. m no , .., .. 11>10 2.19 1>.'.1 2110 l~. .. 1I1nl_. Aug. '" " '" .. .. 7/,1, l.01 '" '"H2 U lOilO SIP', 4...... " '" '" , m '" l.UI .., 1110 " '" '", " '" '" '" '" W.,,,t YUt 1931 " " '" " ~,d ~OU, ..,... 19, 1930 ..... 112 1I~ 2/,00 J.26 m ... HM 1I1nl_. A"II. 3. 193!...... 1.210 .. '" 202 .. ~550 ,., lO~ .., '"", '" " '" "" ." "" ." W. .., ,.., ~, ." IIlnl ... , A"II .. IJOO'" '" '0, , '"n, '"u, 0.' 1960'" m '" ,., 1260 ". ." '" '" VAtit lOu 1935 " " 1t.. 1.... J"n. 1935, D' m 29'. ',J4 :11K .. 14HQ ~.O\ .n ~.J 2l'.O ,.. Kl"l.,,",_ AUK ...•. l)bO .. " '" H' ~J1 l.> ." ...... 2190 1~6 '" ,.. " " "" " " '" '" '" I.' .. ...: ..,; o.-.

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W.. LiI! Ydr 1'J48 19~8 _. ~, ,.. 11011_, Jun...... •.• ,. no 'I>'> , ." ... 1.9 0.25 1320 1.11l) 1980 IIhl_, July ..•.• ...... 1220 "' " m , .- .., .>t ... 2180 ".212 'I>'> .., 1050 /./ '" " '" '" '" "' Was,. Yd. 1949 " '" lIoal... , hI>. 19~9 .. m In , 'I, .. .JO 1220 I.I>Il >I' .., IBM .., 1I1nl_ pr .., , .~ 21\ 1010 ...... '" " " '" '" '" '"". '-' ." ." '''''" '".. '-' /.9 W~ltrHar lhO , .... 111".. , J"n. 19S0 .•..•..•. 'OP ". ... 1190 1.62 'I' ," '", ,., IBI.O ,.. 1I1nlo.,." ""II". .. " " '" >t" , '" '".. .. .".Il 1410 nil .. '-' ,.. I., II "' , to, .. ",.PO ." 1nll 2,,4 .. l!\Ioll ",'" " " '" '" ",'"' '-' ." ." '-' ••• W'''~rYr". 1951 ..... 1_. ~.. b. 19~1. .. t" I,a 169 .. .0 .>1 1321) 1.81) ~21 ,I,t 1011l .., !'Il"I_, July ...•.•.•.•...• , •. "' .." " 11,1, '"116 " 121, U ." 151 1.0J ISIO 26~ "''" '".., 1161) '-' WAur Yur 1952 '" " " '" IIA.I_. Feb. 19~2.• , 'I' ,...... ,... 211 ,~ '-' n80 .., .....a. 10 , .. ,., IJ~O IHnt_, m" '" " '" '" to' .11 ""'" '" n ." ,.. Wa,er rur 1953 " " " " '" '" IlAd_. feb. 1953. .... ,.. ,~ , U, ...... ,~, ,... ", '-' HIO .., Itlnt_. l'l.r •...... ". .. " .. .. '" , '".. .. U ...... •••'" '" ,.. ,.. " " " '" '" '" '" " '" -I> Wn ..r YrH 19S1. to> !'I.. L_, 00<,. 195J ...•. ..", W. , HI) .. .. I nil 1.08 l'o8 ,.. ,.. 2290 .., ,~ ." ." ,y. JAn. 1954. " III"' "n ""lOP .. .. ISlO 2.08 U~ '" ". HIO '-' IIlnl1.".. , AUS •• " .. ,.. ," '"HI. 114 .- .".n ,•. H')'" .., '" " '" '" " '" " '" '0" Wnlr V.at j9~5 .. I ~I) .. 191, lldl) i'luxl .."., F9U. 1955"., , >I , n" , .. .., ).28 10' ". J(,IO 8.J !'Ilnl.."., July 14'J ,.. , '" 00' .... m" "" ,n t.' 1200 ." " '" '" '" ." "" "" W.o.r Vur 195~ "".1_., Feb. 195(0... 10. ., on , 11)11) ., .11 1100 ~.n .., .., 111.. 1]7 "''' 1_. July .. 10' , ." .n l. ~" '" '"III .., IHO , " " ", '" '" • '" '" '" " . W.... r year 1951 " IlAd_. Feb. 19S1 ...... m , 1261) ...... 1.02 •. 6' 27.~ 4911) .., !'lin!,""", .....~.. , .,. ." ...... '" '"" " '".. III II. .. . .Il "" ." ." '"'". "...... , W.' ..r year 19S8 " ,~ 1\;0.1_. "O~.19H .. 'J .. 110 1080 , 1151) 1O'J1I .. J8ll) >.~I 96.2 ". S690 Itlo,t.,u... "'''8. I~Sll.. 1010 .. " .. , .. ." ." ... '" ".., '" '" "" '" '" •••'" W.,or y"H 12S9 " '" " " '" Jun. 19~'i. , .. 1,0 !/>O ~, 1,81 ~46 "',d_. n ". , J8 '/.8 ", !'lInt...... "'-'r...... 82~ '",. " '" '"19l , '" .. .. ." ... 1360'" 2}/ .. ,.. ''"' '-' " " " '" " ." '" '" - .. .. ,.;,..: ,c..; coo .ooO .. . , -- ~gt; o>o'"u- e_ .e ~ ~§ .. S" ~;; ~§ ~o. ::; a· ~~ ,- .. ~~ ~:: E~~ .- .s,Q.g!! <" .. Jl~"3i="2 ...:-' ..,:,.; • o. - - ...0 5.8~ ~:; ~~ !:: ~~ ~~ ~~ ·u ~• -, - -- li- -- .u , E ~ IE O' ~;: ~~ ..",.. ~~ ~~ .- ~~ :-.. ~~~~~ "'

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(kuult. In .1111 ..... 01' Ilur UC~ I .. Ind(ralrd Diasoi¥ed ItOlld. ltarM,,, SpeeUI DI- llIeaeO, ,~. M,~ Meg· Cu- "". CoJ- P'- ear· Fi~ Ni- B<>- dlum duct. 0." Iron ~. Sodium Ia.- SuU,to Chloride lUlU. CoJ· OUcwa:.~u~~ dum bo,- lrate T,~ ed· ~. pll (SIO.) (Fill (Na) slum """..", (50.l leI) ,"', 1("".'; clum. coJleeUOfI'" (e'.) (ell) .", (P) (NOJ ""(Dl To" ""'.car_ micro· "=(Mg) (K) ) (COol pn p." Ml'(- ~~~- (HCO, acre· ~. hon- mlll)ll at Iller fooi d., l'IIHo ("'11"/1 ) '" iliUm .i, 2S"C)

fI·1W,. RTO GR~~OI!AT 1"011'1"QUlfl'lAli. 'TlX ••• Cnnlln""d

101"'0[ yeor l'~O 11 ~p<.I'~O ,. ~.4h .., .. 1_...... , .... , ." 1710 .. 0.6 0.27 _\lM '.78 .,. Hlni ..... June ••••••••• " .. ""... '" ,,,'" , m .. ". .. 1110 2.33 10\0 }'.,'" "LO ""2660 '" " '" '" '" "' 1/.,,. YUr 19~1 .., Haxl_. fr.b. 1941 ...... ". m , ...... n 2680 l65 on ". ,.. 4010 Hlni_. Sopt, ...... 1190'" " '" ,eo , '" '" .. '-' .n IIlO '630 -i'J ,..",.. 1190 '" " '" '" '" "" " 11.,,0[ Ydl" 1~~2 .. , I~ '''.. i_.I1"", I'M] m 2120 l. a70 .n ." .., H2O 1.9 Htnt .... flay 1942 ...... )OW'" .. '".. "n '"II.S '" '"Il4 .. ",'" .".n ... 9'1110 1101 :1.1. 111111 .., ~1& ,., June. 1,0lO .. ", "" .. .., ," '" ai, .. '" ... 1520 '"121 '-' ,.. " '" '" ." '" "'" W",nr Y~nc19'.l .~, "".1 ..",", ALJfI. 1941. -. 216 ., ." -. , ... 111~0 .- 1910 l.96 Ml 1,1.\0 '-' IIlnl_,"" O<;t. 19,,1. lOBO !Ill , 1.'1 .".21 1150 )3~0 I.M .... " no '" '" .. 1.56 '" ". ". ",. 1780 lIu.nr yu. 1')1,4 " '" I\Ioxl_. ~pr.1944 .. 1]1 .- 110 , 1,'11 .. 2.ll4 l,e\O ,n ....., 1210 .., Hlnl_. S~P" ...... - m " '" m'" , 'J61 .. .".30 ""IMIO 1,91 2610 ,.. ,.., , 1160 .., ." " '" '" lI"tpr Xur 1%5 '" 11.. 1_. J""" 194' ...... m ,,, , .W .- ., )110 4.11 W, 686 41)0 .., IIlnl_. Apr. •...... " , ,"" .. .".,. 18lD 1.48 ." ,.. 281.0 .., '"" '" '" '" '" '" '" " IIIUr x.... 1946 '" "" " A ,~ .., l14.i_, A"g. 1946. 10SO , 9~9 16S0 .. 4J1D 5.91. .~ IlOCl [(!lO 1.1 9~1 ." IIlnl .. ,",. Oy."" '"UI , ., 1760 2.39 4\70 ))1. '-' ..212D" '" '" '" " '" Wat"r Y.a,' 1947 " " '"

)1,[ l1~O j(1~U ""xl .. "" J"ly 1~,I. .29 , ,8100 ." .M I,B20 6.55 429 \'JJll 11',0 ", 1360 ", Hl"t"",,", (.10(. 1946. " II, ~ '" m IdO I.~I .. '-' ]620 2.20 ?1JO )II. , , ~5\O '" " ''" " "" " Watur X~ar 194~ 11:,,1'0"".J"ly 1')1.8...•....•. .. 37) 1231) UJ 1070 1970 7. ~ ... 5190 '0; IIlli 179Cl n8C 7660 111,,11""10, Join...... m '" >Yo ,• .. .., nlD l.OI n. "9.) H2O " ". " '" ". '" '" 114Lftr X."r 1949 '" ,~, ,~ 11... 1.... "";' 1949 ...... , ,.. IUO ..... 1.240 ~.16 1180 64~0 .., HllOl_, S"p<...... '"II.~ " ''''''m , ... 1110 ~.}1 HIO '0; ., ",, 7660 .., '"" " '"". '" '" ." lIa,.·. y~... 19~0 IIIxl_, ApI'. 19S0 ...... IlllO , IhlO ... .W 4l~0 5.'11 1190 (2)0 ... Mini"""", July ..••••• ...... ~JI, '"141 , ,'".. ,., .7'1 Ib50 1.11, 2380 ,.. alO '-' " " '" '" ", '" '" '" " 1I",.r X~.. 1951 '" ~, M-o~!'""'"'19~1. ]",120 , SI~O Ap,-. .., 11', 12]0 lOtIO ., .n 1.01 IIHO lnO 7~'O ,. IH,".,"". A"H. 128 .. , 12h ... .12 ... 21 , ..",2.J ,., '" '" ' , " " '" " '"' '" '" Table 7.• -s..-., n(

Mro"llo In .nlt c~... • lI!~rnup! .. l"dl,~I~J DlallQlv«! aoHdl Hardne.. Speelfl U CaCO. M.. _ DI- Cu_ "'- ,,,- Date M'M CoJ- '0- ear* Floo Do- dlum duet. ,,- SOdium - bo,- Sullate ChJorlde ",- 111111_ CoJ- of DJaeharl"e ~~~~~" dum ... bo,- ride trail! No,- ~, .N (SIO.l (Fe) (Na) slum oJ, {SO,} (Cl) IIrn.R ",,, Toni elum, ~rp.""- collC!'CUon (crl) (Ca) ,,= (PI (NOJ (01 car· mlcro- (Mil) (KI ", (COJ '" p" pO' Mag* tlon (HCO.) acre· do, boo- mllGll at HI"r." ,,- oJ, nllo 2S'C) (.. till) "" ilium 8_H05. RIO GILANDl':AT FORTqlllrKAH. T~X.··Conlln"ed

Wal~[Yu.' 12~2 1\&.1.."... ""'. 19n ...... 5.1, ". 1~50 751 , 129!l 2690 .- 0,0 U.17 ~~'O ~.II '1'1 ., l~~ll Inn g/ll.1! MInI ..",., ~"M,. 11,11 '" , m 1.:14 .. .4!l 1120 1.80 111.1 .., "" n" '''' ". "" "'dO'" 1I1n,f hH 19'3 " Mlt..I ...,.. , J""" 195)... , .•.•.•. LO 8n H:t 2',40 on , 1710 4820 .. .. 10111!! 14.~ 1,11,1 ))Hli )210 15200 MIni .." •. J"I, .....•. ,.. , ,. .2'1 IIllI) "J.J 1190 ""LO '" " "" '" "" '" '" '" "., '" 1I"'Uf Xu.. lU" Mi,al_. OC~.I?H. .. m , 1420 J2)0 -- ... 9120 12.4 I? 1 JVlO 2200 11800 ,.. I'Ilnl .... ~u•• I?...... '" '"'' '" , on u 101 OJ lUlU .., '" '" ". '" '" '" " '''' ." "" II.. L,. yn. I?» '" , 14)0 '11~O Kui .... """. 1?55 ...... • ." 8JI PHil 4190 .. .n 11.4 ", )1)0 1120 l)llHl l.' Jun...... 00 '" 1970 '"no , 14)0 U'O 2150 12.4 \.4' 1110 lUO ".., 1,100 lIinl_. J"ll ..•...... '" '".., , L> ... -- " .. " " " '''' '" '" ." '"' '" '" " IIOlsr YUt !?U "" .... i_, 1'1"".19'5, 1930 , 1490 311BO .» 11.7 ....1'11'10 11110 121100 '-' ~"IL, . I'Ih,i_, 19)6. ." .., , , OJ, '" "" " '" " • ." ."",.. ." 12.1 "u .., 1I00n Xu, 12)8 " " '" " '" .... 1... , hpl. 1'~lI.• .., III !l In ,., .00 1,91 .., no ,,, no ,. "'ni ... , 0<. 1957 ...... '" " .. " !61 0 )'1 " ... » 11.1 , ,.. " " " " " " '" ". '" " '" ." l> 1I""r Y~a""S2 ".. hb. I'W ...... 1 ,90 ,,. 1120 lOlO L> .~ 10.1 4.18 2\10 OJ ,_. ." ...,., ' -- 1S5!l noo '00""u 1'11"1_, J"I, ...•. ". .., ,.. .. OJ 6~1 ... 15.5 M,lI m ,.. " " •• •• "" >." ".. " 11"1<" y,ar I?§!l .." 11.. 1"",,,. It"". 1'lbO... L' n, 71)0 11)0 H80 ,, '11040 D.I 18.6 HOO llJoo ,.. ,~ L' Itlnl ..... 9 61.8 """ "'ll " '''''' ,. II"" .. y... , 1%1 "" "" " Itul_. Jut, 1261. ... lO?O 74\ 1110 lno LO ,, ,., ~)IO 11.1 '1~., ~140 I'JIolI 11000 ,.. 14101...,... ~u~.. '" ,., ...... ". " '" " 'n -- .. 1,92 1111 "LO 71,7 ,.. ." " " " " " ." '" " 11"'11, YOlOT1?',2 ~,~I _. ..,... II.... 1962. 2140 1~1l) ),qo ~I,r,o ,., 6,6 w .- ..LO H9'11l 17.1 ~"411 12500 U 46 , ,n 1,6~ 111nllOu". StpL ...... 2n 1,\11 !,'J l ~1I11 Vol, "'' " "" '" -- ."1 1790 2. d nl,o'" 2680 I.' IInl! haT 11111 " 1'1 ,., •• 1." •• h,,,. 126). 227(} 2,7 la'lll )720 .. ~14!l ." ' ..L' ". I 12', H'>O IHD 70 ~"W. ,,. I'll""."., ..,. '" 10J .21 10~0 1.41 , , ""'"I~~O " " '" "" ". " '" 1111" y"a. l'IM " '" "" " ",,~I ~pr .... 12M ..... ,, 2n '00" 1810 )/,10 ,, , 6140 11,2 ~I,.] nil! 12400 U .., .~ Mini ,., 4.0~ ..... UPL •...•..•....•.•. '".. '" OJ ,, .. """,rn 0 .., .., " "" " '" " "" Tabl~7.--Su_ry of ebe.leal anal,a .. "I T~.u .',n_ In 'be al" Gra"d~I>o.l"-_(;",,~I,,ucd

(acnlu In ..llI1I1u_ ,",C litoc ucept .. 1"lIldl"lI) m ohlld IIOlida .. Hltrdncl.. Specltl m- •• CaCao So- can_ Date Mog- po- car_ Cu- dlum M,~~;~IC"'- FI., NI- Do- duct- Or OJecbarp• llIea Iron ",- SOdium 1.. - SulJRte Chloride lUll 1_ C"'- clurn "",-,~ ride tTlltCl Non_ anee pll ,1= (Na) slum "",- (SO.) (Cl) K"'~"II elum, "'-orp- eolll!'Clion (,ro) I(SlO')1(F.) (CII) ,I. (F) (NO,J '"'(3) !ler ear- mlcro- (Mg) (K) pO' "'" I~' Milg_ (IICOJ (COJ lIere- "'" t10n t I 110",' do, ",- "",- r",,1 .~ ratlo Im:;!ci (1111'/1) slum

8-)705. Mill (;M~U~AT ~OMT Q1II'lWI~,TIl~,--CM'I,",ool

~u.c 19~~ VM< _. 11 S,,~t.1~G5. ,. .. 11.""" L< I'Ib O.Ui 1,\1 fU7 I" ~bll , ,,. ,. Hlnl ...,•. "'''1.' ,, , .., .4~ , l.O .., " "" " '" " " " ... '" '" on " '" !/.!~.. Ju~r J9~b H.. ,." •• ~"I't.l~bb no ,YO m ,. 1420 J.~) .,. ", 2220 ". ,~ '.1 1l1n!." •. July ...... '"11.9 .. ",. .., " '" ,..., .".•. 40) ... '"15.1 ,...... " " '" • " I" '" "" IIn"r TeAC 19~1 l'I<.t..... , ""y 1961 ...... m 2390 , 2020 19~0 1.1' 9940 13. \ 7670 2V,0 20 IlAOO ,., Hinl_, Jun...... , .. r.'" ,,, ...... " " '" '" ." '" '" V,,'nc Tn... 196R " '" " " '" 1'1<<1_, ""1 196' .. .. m 2220 .. 1920 .- &860 11.0 2160 lO 1/.00 .. .. ,~ "00 , Hlnl_, Jul, ...... on ".n .., >0' • .".n 1. )6 , 1550 .., '" '" • '" ""'" .. " '" '" . fl_l71ll. 110 l:ltJHf\)~AT 1.0\ NlITllIA, fU.

fir 1,,01 J~" - A". 1'111> 11 ~~ ., ... 1.... , •• 29, 19J6...... ". .., , 1.'1 0.42 1,.70 .., .., ". 14HOO ,.. Hl"I ..... , ~u•• 31. .... m" .. ... '"n , '" "" U .1/, "'".., .., ., ,., ". '" " '" '"' " '" '" \f~,"c Y"oc I'I~I ",,"10.,,*, ~1'C.10, 1')1 lll~ .. 8]J ". ])50 H .Y. ll'.o 'J. 10 8~U 11~,() '11M) ~~IO 1,1,1, ~ Hlnl",,~.~'~l•. ,.. '00 ," Y., m 1.0 lllil 1.81 1'00 "~.ll lllO .., " '" " '" '" ". '" 1I.".,c V,'M t9JR "' 11,"1""111.0<1, MO"., Uu •• Inl. .U 1,8 m , 6AI .. ... 11KU I.'H' "dO 1,70 1,'1) .., JJ90 .., '" " ", 1l1"I"urH. Supl. 1'118. 1llO '" 'M l4~ ,., • 1~ 1,)1 )1'0 19~ ... I ~~O ... " '" • '" ." ". II.".,. yo,,' IV' " Il.'d"u •• AI"', 19)9. •. Ill. .. .1" 18MI .1.119 ~~S 6il:, .., 4:13u 1l1"lrH"••. 1,,1,. " '" '"., ,• '" '" .. 1'70 '.ll I,'JI, '" :1'. .., 1520 ..,'" '" '" " '" '" '" '" 1I.,ot ys"r 1';0 II.. ' ...... Apr, l~~n•..... , .•. ., 171 , .. .Y. 28?0 J.~J I?~ ... 141 ~ .., 4490 , .~ ". II,) , '" ", . 11101"",., ""8 ...... •...•. '".. ,.. III .'18 ... 'IN .., .., " " '" '" '" ". "" JeI".L.V ..'~r!2il ""HI .." ... N,,'1. 191'\l .•...• 17', I(J4 "4 , 2I,'JO 1.1'1 11/0 .., 3770 ... ,~ ,,' Hlni .... , 8,'pt. 19/01 ...... 1180 11,1". , .., . .. 1.10 18'10 1',0 I,.~ 1290 " " ... '" '"... '" ...'" rulli,' 7.-·S""n.,ry "f d'dd<.,1 .""Iy ... of l'"K~"3<"''''' I" ,h~R!o> Cu,,,l,· iJ.,oil'-_G,,,,U,,,,",1

\K~""Jt..'" ""ll~r~.." 1"'( 'He" ex.,'!'" ~" "","""""') Dlssolved soJlds Hardnes8 Speclfl fiI_ as CaCO. So- M",_ p,- Car~ con- Date M,~ C~- car· Fluo Nl- D,- dll.lm dud. SU~c~ Sodium fa,- Sullate Ch1orld~ 111111_ C~- Olscharge clum ",- hOIl' ride lrate Tona Non. od- pH collection" (SID.) ""(Fe) (Nal slum "'"- {SO.} (CO Tons ~lum orp_ ~" (chI) (Ca) ,'= (P) (NO.) '""(6) 1:"""''' po< • car- mlcro~ (Mg) (K) ." po< Mag~ (HCO,l (COJ acre- tlon nhos at "" 1 i leT ",- "',- fool ""d" ratlo 2S"C) ("Il/I) Sll,lUl ,"

~

Period Hb, 28 _ s~,," '1-7 IH~ ~,"l.. ,." liar. ~B. 1935 .. f.m % 77.1 m , 9/,5 lJ~O ..O. ~) !,030 5./,8 16. J lI,lQ 1310 .., 5'1~0 I. ~ 1'11"1",,,,", 29 , U 8,1, , " f, J41, .1,1 bB.1 14! , j""e ... 'f.'" " ," " " " "" lIac .. Yeai' 193b '" " 1'I~.l.. ,." "pc. 1~. 19:1h •. '-.4 HII 595 m m 1080 ,, .n 1I90 I"JI, 20.7 1190 1020 1,81,0 1'11"1...,.,, J"'Y 2~"...... , >.. "'f. jI,2 \ItS ," '", 1.2 .f> M~ .9~ ~31 ~~~ " 11/,0 '" '" '" '" '" '" .'",,,, Yd. 1937 1il>.llO"", JoI'y 19H 1.7 no Mil , no ,m, e., .!,6 J21,0 1,.1,l 19.2 1160 1020 oHO ,, MI"I .."",, h"~. , l,l6 <.,1: .. " '" f" n " , '" " " " '" '" '" ." '" '" "'. 1I"'"r y."c 19'j~ M;.. l..,,~,H"y 1938, ,m n 0 YO, 1.2 .24 2,l90 J. 2~ m .., "00 Mlol."., Sopt, .. '"' '" 0 '",~ AJI 1.D 27,JO'" '"" I"J l]/,o " " ". '" '" '" ." '" If" "" IIs,o, hOt 1132 '" Hul ...,•. hpc, 19J9. J51 'M m Il',o 0 f.' ]020 I, . 6~, 231 1180 9'10 ... "O~O 1'\10110"". Aug•. _ 1,51" .. " "0 ""'26fi !td 99, J. 1~ 12111 '116 ,"00 "'O. , " '" '" '" " WHH X~u.1940 Kol~l","".AI". IYI,{I.. (,1~ , m WoO .0 3110 ',23 n. 1080 8.2 ~710 .., Mini ..."•• j",," " '"10' " '" 0 m LY 1.1J )28 '"2·11 3,) IZflO .., '" " '" '" '" '" ". W.. "" r.". 1901 K8~I"'L.,","c. 1941. m YO 0\0\1 m /71. 1080 .. J220 1,.J8 591 1020 83/, 4610 ., 0 Min!"",,,, .holy ".",., 6')1,'" ". "0 22', n, U 8~J I. 16 "00 !ilO " 1350 ,.. '" " '" '" " '" '.' IIHer y~al'19/,2 Ms.loou,,_ NM. IYI,l. ~19 , m .0 2520 l, I,] J950 , .1850 ." f" . ... Mini""", Sep' 194?, alO'"' '" '" 0 2/,0 ,n I.~ .n ... I.IH 59)0 '" "" 1,,0 1310 " '" '" '" '" 0.' WAter rear 19/,3 " " 1'\8.1,,",,_ A"~. 19Id. 4}" ,YO ., ,"0 m .1,/, 2960 I, ,OJ 781, , 0<.90 0' ,~H . Min!"",,,, 0.-" 19',? 1?90 2/, n~ "0 '"'no '"287 .0 .<> 111>0 1 ~(l"[)"" '" "00 '" ". '" '" " " Woe",' r"ur 19~A Huh,,,,., Huy 19411. ow. 63', f.' alo J.I.' 0" ", ., .l8S0 fl . .! Min!""", .1"ly...... m'" '"' " '" ," ,.. '" .2~ IJJO 1.81 1290 ...'" 2711 (,,2 ~MO .., '" " '" '" '" • WH~r Y~'" 190~ 1'14.1.,0lIl, AUK. IY~), ., no om 10lO , ,1,9 32J0 1,.J9 1060 0" .., 0660 ,. MIni ,,,, j"ly ••• 511'" '" 1'.2 , LY 1.01 10~0 l4~ 11.6 11/0 .. n " "'. '" " '" '" ." '" '" ).9 1I~[orY~4r191.6 1'I,,.l,.,,,", Apr, 19/,6 .• ,.. '"00 1310 . ~, :19,0 5.31 ,,. l)7l! I?nll .., "00 , " Hlnl." .. sepl •.• no" '" " \.17 '" ," In M' ... 127 /.. 2 lOW ,.. " " " '" " ." "" '" T.blt 7.-.s_.y of che..l<.1 .naly ... ~fTuu •• ~ru",in ~h"RI" Gr~nd.blo.ln··CoMlnu~~

\n~.",<. ,n .""lIr._ ...... , .. uup' •• ,,,,,'u,,,u, DI8lJoI...ed 1IOilde ll....dnll8. Spcelrl at CaCO, p,. a,· "'-

iI-lll~.RIO GRAHll~AT UPPER PlI;KSllllll, nx.--C""ll"".~

Wuu Yur 19~1 Hul ... ",. J .. ly l%7. O.J1 .. , IHO 1)60 5]30 7.11 2.91 19~0 lUO ., "00 111,,1_. Sept...... • In ". eo, , ,~ 1.9 0.1\ 1.20 ,.. , , 1))0 " " '" '"" '" " ." '" '" " II•••• Yur 19~1I ,tnl_. lI.oy 19~8.", ,"' "00 , I~IO 1970 L> .» 5820 1.9l .9/, ,,,, 1960 .,,, I4hl .... A"g .. u.~ '"u , ,~ ... >U '10 " " " '"" " " " " " " 'OS " II... , Y.u 19~9 ,,, H~(l !lui ••"•. Apr. 1949 •. '.1 ", , 1010 IHO , .}6 4010 5.1·) 56.1 12611 ... IHOll.... J"ly .. .., '"., , ,.. ,.. 67.2 '''' " " '''' '" " " '" '" " ..." lIunr Yue 1950 " fI"xt,.,,",. Ap•• 1950. JM .. .. , IO~O 1~IO ., 4~I0 5.1) l3.6 11'0 ~160 111"10..... A"8. 1~7" .210 eo,'" , I,] 1.31 ''''lb'l lUH ",,' 1 ,80 ... " " '" ." '" '" ' W.,or Yur 1951 '" ~MO 1'l.,.1_. Kar. 1951. ... , 12)0 16eO .. .W 6.65 19.e 1120 ~9~1I Aut. .., , >0, m ~6.I n~ 1,1 1.1i ttlni_. "'" " '" '"" '" " " .,' ... ""• " >0' " 1I.. "r yc.r 1952 H.. \_. Apr. 1952 ...... , , ,,, U n8 8.45 19b , , 1010 ,.. IIlnl_ • .Iuly ...... •. >0, .. ".., '" '" , '" ,., ." ." "" ,., 1.1 " " '" '" " ." '" " ", '" " 1I,"r Y.. r 19a '" 11.111<1_. June 19n .. ,.. .. , -. ... 11. ) '-' U1 I4lnl_, A"g ...... II .. » 163 , .. ... 68.l '"., ... ~ " '" " '"'" '" '-' '" 1I0lf[ yur 19Si, '" 1101<1""". S~PL 19S4. ., .. no 2Ul .. .. Il~O 1.61 HI 1• .1. 1100 IIlnl.,,",. Apr...... '•• 6 .., ". ," '" '-' .OJ m .1.6 '"~.5H '" '-' ~~O ... " " '" " '" " II•• U year 195} IIoxt..,... N,,~.195~...... •.•. .m 0 -- 21150 l.66 9/\ 4Z90 tllnl_. A..g. 1955. II '" , ." ., 61.7." "',.. " '" '" " ." '" """ '" ..... ~.. IUr 195b ....a.... , Iln~.1953. ." , IUO .. 6.19 .. IUO 1510 .. 6UO Mini ••• A"S. 1956...... " '" , "'" 28,6 ." " " '''' '" '" ." II.. " Y.,.r In1 .... \••• June 1957 ..... , ~. 1'1.1 ,.. .., I4lnl_. l1.IIy....•.•....•.••.•. "» '" , .~" U.2 , .. m "'" '" " '" '" '" '" II..... yur 1958 ..... 1.. '•. "'y 1958 ... 0 .. 1.11 4/.6 .. 1010 IIlnl_. Oct. 1931...... , "" ,1,0 l2.0." 1~6 '" " '" " '" '" Tabl" 7. __ Su""",,,'y ul d'e ..le,,1 ."oly"e" M fe.," '''ea ... in ,1,,, Rio Gr.n"~il"J{,,--\;""'{n"<',1

(Xl'.ult. I" .. Ullgru ..' p"" Ill'" excep, •• lndicated) Ollll:lolved aollds Rardnll1l9 SpeeUi all CaCao So_ M",- N'- COtt- Date Col- Po· car- Cu- Pluo Do- dhlln duct. M,~.l~Iron ",- Sodium ~,- bo,. Sullntc Chloride N'- lUlll_ Col- of DJ.Bcharge Slilca clum bo,- ride trate r",,, Ton. NOII- L>d- plf (Fe) (Na) ilium :lte (SO.) (el) II'!'.'"'' Tons clum, ~" coilecUon (Ca) ,,= (p) (NO,) (D) pO' car- orp- (micro- (,f,) 1("°') (Mg) (K) ," (CO,) pO' pO' M'lg- acr\J~ (nco,) bo,- tiOl~I;"IIQ~at II tf'l' d" ",- ("K/l) foo' ,'= ." ratto 2S"Cl 8-J715. ~IO~K.\N~~A'f UP~~ ~K~SWIO,'rH.--C""Unued

W.tC" Y~"r1959 I'l.d ...... lIe~.1958...... 0.59 \130 m 0 2110 "MO 8.8J 10,3 H2O 2\)0 8680 MI"i.,,,,,,, 19';Q. , :1'1 .(l.~ 1/'- U ';4'; J'm" '" '" '" -- ,~" " " " W."," Y~".1960 /IA.I...... Aug. 19,,0 .•.• )/,8 m CO, 0 H') 1010 1.31 ',0/, H2 1,.5 IHO -- ,., 111,,1...... ,. Oct. I~SQ. -- , ,4) Il.l ""('/2 \., " " '" '" '" ", Wal'" Y~"c lq6\ 11.. (_. ~·.b.1961. -- ~08 , 1130 HIO i.. 11 19') .., 1~1 ~~I0 I'll"l ,.,. i'lIIy 1.11 , I.hl .hJ ,~ 5 1(,8 .. "." " '" " 21" "'-" 'II W", or Yoar 1~~7 118> " \la,,,, Ye.,. \9M " " i'Ul.I,ou1O. l!~o.1963. ~.~ -- III 0 4ill 1140 I.. n ',0.0 IUS 6lJ ~6~0 I'll"l .."... J,,,," 1'J64. U .~~ .')'1 m Iii " ~H -- '" " '" " lIatllr Ye.,. 1965 " " " Koxl"u,.. Sepl. 1965.. ~~ 137 , I,n ."' 41.. ~ nil u 1'l1,,\twU". Aug, .• U " .., .b'j ~.1\ { 14 '""1m '""b4; '"tv " -- " '" " " '-' WUl"' Yd' 1'.166 M.ul .. "". ~Qpl,19~6. IdJ '". ". 0 -- on UO '-' 111"\.. ,,,. A"g .. -- ,., '" /'12 "' '" '" '-' '"614 " '" " " " '"' '" " Wal"" YoM 1961 11.,.1 ..",", J.. n. 19h1 •• •••• 1))0 0 2070 1nO 0 .• 0.6 1150 9.71 1500 1J90 9 ,60 no ", o.n ' '-' l'l(nll.",o, "'"g.. -- " -- '"' " .00 "'-' " '''' " '" "" "" ." '"' Wale" Yd' Iq6~ !1«xi.,,,",, f"b. 1966.. , 111, 1180 1.11, I,ll. 5-', 1810 ~Inh".,.~opt...... -- -- '" 19/,'" , ,. ,,, no '"".. '-' m " "' B_lll,O. MA~UTO CREi:K ~l:ARPRESWIO. Tl'X.

P~rIM fob. 193~- J.ln. 1936 l~H ~2 Itdxi ...."", Apr 2B, . 2.G 4. l ,~" U 0.26 /,810 0.60 2,6\ , 1,.5 ,. ZI.'.1 '"" '"25'1 I'll", ..,,",, .lu,," II. ~91< " ... '"' " " ., , " " '" " " "-' " '" -" "'. " '-' ...:..:

c • cO £t§~ cU ~. ~u , ,;.:. ' E == ~~;~.; ,"

N- O

... : I ! , ,•

o. C.

·53· T"bl. 1··5u_,y or d", ..I ... 1 u",,11.~.". T~..... ~..... I~ th~Mlo r.",~d"h... ln __ C<>n'.jn"rd

(~".ul,"jn .lll!~o"... ,,·r Ilcc' ""cu" ". 1,,,IL,,,,,,,1 Dl8IIol"ed sollds 1I1rdneHIl Speeltl aa CaCO, .,. no- con~ M - p,- Cu. dlUIll MUlln CO>!· .. ellr· ~·luoN,· Bo. duet- 0." ~oo Sodium lUlll- CO>!· of DilllclUu'a:e U" clum ,,- .... boo· SuUatfl Chlorllkl ride trate Too. Noo- .... ~. ,N (SiO.) (Fe) (NO>! aium CO" lI;r" .... Tons clum, ~rp_ eollecUoo (da) (ClI) ,,= """..t. (SO.1 (Cl) (P) (NO) (U) car- micro- (Mg) (K) (COJ M~I- (HCO,) "" P<' acrc_'" P<' tlon mbolilat I t1

8·)1)0. RIO r.RIINI)K liT JOIINSllN kIlN~lt,nx.

\Iu ..~r YeU' 1948 ,~ 1'1".1"".. , J"". 1948 ...... " ", '00 ~()/, , IW O.~ 0.22 ." I.ll 1~~0 H' ,.. lJ60 .., ~1I Mini ..."., J,dy .•. .. '" '"".. , '" U ,II, ./'1 !lOO ". ,. "" " '" '" '" " '" "" W"cc' Y~.'19/09 ., H1~ 1t.. 1." •. ~p'.1')49.•. "" ... 41)/ (1,8 no , L' .11 tHO 1.66 lJ20 loj1 .., 1640 >.> Hlnl ...,•• II,,~. 29)0 ">.> '" , '" " U .W .. 3960 L' .., ,.. " " '" '" '" "'" '" '"" \I.,~rY~H 1'J~fI Mo.-I .... Ja, ... ", , '" , '" "' ." '" '" II ", Y1_. JUM •. '" '" , ,.. '"" " ", '"" '" .n '"'' '" '".. ... '" I/~,~. Yd< 19S~ "-.1 ..... J.n. I~~~...... ,.. , ". .. .,. IllO 1.11 ,..., I}eo .., 111,,1_. Aug •...•••• 2810 '" ,..'" .. ll80 1l)~ .'r L> '" " " " '" " ", ."" '" ". lIotH Yo", 19.~6 1,28 1~60 11•• 1",,,... lIo,y 19'~.. .. ,.. , 1',4 H80 1,6f1 ... .., ", ,", Mltll"",... Oq ....xr .. _. IIor. 19~9_. on 1'1110 1.88 ... 1890 1t1,,1_. S~ft•.•.••. 1160 .. "... , ~. .14 n. .. 1. ,I '" '" " " "'""" '" · '" x : : : : : ~ : · : : : : ,- O' ~g*~~:F ~$ ~~ ;~ ~. ~~ ~~ 5~ ~~ !u~·l~~ - .s.';"",.s "' .0 .. _. ,g~"S!ig~ .. 0-

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(He."I,. in nilllH,"m, I"'" II'e' eXec'" d. l"dl""eJ)

1lL811olved llOUds HllI'MC88 S~dn ao CaCO. So- DI- con~ Po- C~- tllum Datc C.u- ~'luo duct. ,I~~I..- car- ",- Do- Dil!cllarg~Mo., \A,- Cllloride 1(011_ Cal- ,I SUICK Iron dum -",- SodIum boo- ""0- Sullalc Nan_ pH ride trate rOll TonI! slum (Na) slum oto (SO.) (Cll I:,'H"" Ton8 clum, ". coJll!cUon ('1.11(510.11(F'I (Ca) ;Ite (PI (NO,,) (DI ,,, ear- ~oI'P-(mIcro-"" (Me) (KI (co,,) MIIlt"- mll~ (HCO,l p" acre~ boo- tlon at day po. 0 tiler foof '" ,to r'ltlol"2S C) -- (lnK/1 ) ilIum 8_J775. KIO GKANl!~AT L<1NGTKY.TU.

?erl ",I hpe, I - ~''P'.'HI 19~1, 11,4 !Ull ~~b 1.11 1 ,00 1120 .. tl·,xl .. "" ;"ly l~"'" 109n W ' '00 no , • 1I~, , ., (,~~O ',1, ~ MI"I"",.. , ~"Pt. 10JO '., ",., lJl. P " '" · ',0 1',1 ." "l.O '-, " " '.' '"" W,"~eYe", 1945 ,,"'xl ...,,", ~~O. 1~1,1•. 1170 101 I.'J 'J/I 3010 J,'> j'J6 1,,0 11,10 .~1,,1..... , July I'll" 6110 '" r.' '" 1',5 " '"' (I,OH 104~ ..." 7410 I'll 6JI, " " " '" • '" " '-' " '-' W",,'. Y~", 1~4~ tl~xi....."" J~n. 191,~ 1290 I"~ 2()1 l.'j 'J8~ 1.31, jUO ]2', lR[, 1.. 1 1~IO

'" ~ ',~6 ~~I'l. 1,[,20 "' 1M,'" P 4!)", .S', ',0<',0 III, I. ,.> HI"in"",. " "". " " m 1" " , ..." " ~',,,.,,Y,'~e1941 H·uh,,,.,. J~".\9',1. 11,,0 IWI 1M n 11, H90 jO~ l~" J.9 1280 ... " ~ ", ,., ',!>~ MllOl",•• ,. $el'(. M,RO "' "7,2 '" 11,7 ," no '" J,7 .n 1M 41,',0 .. '" '" " ." "" " Wn,e" y. ,H 19.',~ Iioul""",. Jon. 19',8. 911 .. ~1.4 ... 111 .. 1/ .]0 1'310 1',8 U 1210 eo M!lxh",•• Jnn ' ". MI"l",,,,., Apr. [0]0 W II,] " n u ~ JM "' W70 ''''17n ... \bl '" " " '"" • w" ""' '" " ." ~""'eY,'", I'no M.'xl"""" [k,c, 19',9, 12~() 1I,~ <',0 lJJ "b II" 106 "b~O 271, U 1150 8.1 HI"I",,, ... ~erl 1950. Jl010 " "U '" m ," " ,:,8 17~n Il!) '" . ,. _l" '" '" '" '" " " '" '" "' '" '" ~""".Yun, I~'H Mul." .. , Nov 19~1l,. 1150 H2 ~U UN .. ~'> lJ.', 1,'1 77'1 ~ 2/,20 186 U Jl70 MI"i .... , i'ldy 1951, 1)60 '"m " IlJ , , .00" IoJI, · ~'J I '>~O "" .., 6n ,.'" " " " " '" '" "' \lotN Y~",[9,2

l'.l~]. ,,. , f1>l.i .."m, hUH. ". n uO .. , .'11 1190 JI! lBS 1020 tllnI ..."". July .. ~2BO " ., " .r. ., 6810 HH UO '-" ... " '-' " '" " '" " " '" " "'. " ~';j'~,Y~o, ["~] tl.uhn"., 0«. l'JS? ..... 1,~5 w 1J8 278 .., .01 b'll 'II, ~()', JlI, "0 "~~ /.'J .. ~qb ~. lI~r.1'15J.. 1,75 " "' n" ," " .,. ." , .., & 1010 ,.. Klnl"",~.KIly. "" " '''' '"ll,~ " "'J,1 ... 1,/.1 ,I,ll H'I n;' '" 1.'1 "or ,.. '" " " " '" " " "" ~'''~rYd' I~~ ,~ ""xl."•. rob I~)/o, I"U 2) 2',~ ... .ll ·~~ 821 ", 11<1 '-' ,"00 ... Mini." •. hl,e, I ~~O " L, '" " ,"' '"II!> .4·1 IbOO .. '-' Iojlt '" " "' " "'" "" ~8le'Ydl Iq~? t!>x;",t1O Fob. 19}) on l~O III ... lOIO 'JOI, l~~ 10,0 8, I ,~ Mlld .. ,,,. J"no. I1hU "' " '" ,or p " I. •~ " ... II ~tI )(11, ., 7,'! '" " '.' " " " '" '" "" " '" .. ..;...: ,..;...:

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8·4101. I'f-COS R1VU ~f-I.oIRED "l,ijF'" nA~N~AROIlIA. rnX.--C"ntln"",1

W"'r. yr"" 12~] MIlM...... OCt. 1-31, 1~62 ". 2680 2S60 4~OO 10100 14.1 ~Mbl) 2810 lllO 1,2 1I11V. 1-10 .•.•. '" 211, 2670 '" • 10'llll 14.2 6010 2880 Z170 22 141110 ", ".., '" '~. " ""'" ~)""....., J"ly 1-1), 1~~1"." .. " ''''m 1'140 '" • nw "'"lllO .. IllO 1l.3 n,o 14W 11400 ..,"" Wftl~~I.".v •••••. y," ,.. w '" l~ao " " ,• ZI,~O 3210 2ft~0 lJ,1 144U "'"n~u 7650 21" 1)400 ,.. "" '" lIelt( y... 12~~ ..... I~.. , 5., •. 10-30. 19M ., M' 28.1 3820 It4 , 1410 .. IJZOO 11.0 ,.. 1I~0 76100 )7 18600 ,.. 1_)1. ."'"1900 14211 10.1 21)0 ,,,,oo ,., ""'1_, lite. 19n " lIno '~ , .. 2220 W ~~.d 24f, 2210 , l)JO 11.1, J~IO ... on,.,1' .... """ "","" "" '" "" 1\10 'UlO '"11'. !610 " 1'600 .. l/•• ~r Xu. Iq~) 11... 1_ .... y 1.)1. 126\ .. ,., ,., 10. , 11~0 64~0 14400 nlo W,O 11 11800 '~' I'." Itlnl_. 0... 1.)1. 1'1>6 .... ,, ", '" '"221 22~0 , 1170 .. 2020 11.2 '"6~.4 ,,'" 21)0 20 laoo •• d })70 \I.~ , 2420 11100 I~.' 21~0 11 lllJoo Utilh •• ntro ••...•.•. ... ".'''' '" "' " "'" '''' '" !llO ..." IItU! yll' l?~' .... 1_, Mav. lZ.\O, 19n,. .., 10 3790 , ZOIO IHOO 11.0 I',? n80 '1"0 14 19000 Klnl_,.. 1.10, 19ftl>" , ,,'" 4980 6.1/ 14 HI •• hp' .... ., '" '".. '"'~ 1160 U "40 m, Wnllth.~d~ '" ...... e•• ,.,. " ... '"461 "'"II>MI " , 1',1.0 2(,',0"'" 1>440 ".11 1550 " 9900 " '" " '" '" "" " •• W.W Yttr 11101 .... 1_. J"ly )-10, 1967 .., 1480 .'>4 , 1110 ~bl0 1./1 10]0 11"0 1770 8890 l.O HloI_, Apr 1·)0 .... " ... '" ,., '" ".H '" , "'" '''0 1.44 ]]60 ... " 1980 ,.. Il~U". W"IK",~d ,., 291, 81>3 ...... " .•• ". '" '" ,'".. "18 '" '" '",. , llHO I"l'! I? 1(1 lOll! '" " H70 lIlUr yUI iyl,A " '" " "." " 1~6~. .., 16~0 <0 MIl.I ...... l"ly 8·11•. 4)2 ,,'" ". , 1580 H50 "lOO 17',0 .. lHOO I1L"I"",... H,W. 1-6. 1~~7. 'Ill(l 12 , , 10lO 1,0711 1110 IlIO ~OIU .., '" ... ~" '".. ' " , '" 1I.1"ln,." •• ,·r"~". '-' 40~ l'IM) 1100 11/11 5180 11,~fl lHO SHU 1,6 '" '" "'" ,~

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(Il".ull. 1" .. l111~ru,.per IHe' exl_ ta,_ car- Fluo Nl- D,- duct. of D.lachargu SUie ~" clum ",- Sodium "",-SuUale Chloride lUll1_ C>I- ) (FIl) "",- ride trate "0118 NOII- "'- ~" pH (SIO. (Na) slum pta (SO.) (CI) j{"~"'" Tons elum, orp_ co1lecUolI (ctll) (Cft) ,,= ah' IF} (NO,) '"'(D) pn car- mlcro- (Mg) (K) (COJ pn Iler MRIt- tlon (lICO,) lit.e'· acre- do, ",- "",- nhos at .ta rallo 25"C) - ("1':/1) 100' ilIum 6_4415, pr.r.(~IIIVF,R R€~ CRANr,PAI,I,S. nX,-_C"n,fm,,'rl

IIOte< Year 195] l1ul_, F~b.~ 10, 1',-15. \6-20, 19n a~4 1H90 , ))40 I~'IOU l ~~OO 1110 4'IH '" , 8 00 ,i ,•

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"'~'u,_. ~" ul~ , ... "'" n ." ,. " I'" "••••.•• .-••• .n ...l"oJ ,l,·'" Dissolved &OlIds Hardnesll Spcclf! m- as CaCao So- ,~- Date Mean CN- Mog- Po- car- Cu- nuo Bo- dlum duct_ Sl.llcs ~o, ",- Sodium (.1S- Chloride lllill!_ Cal- D18charge clum "",- SulInte ride lrsle"'- 'rona Non- pll (SIO,) (Fe) !Iltull (Na) ilium "",- ale (SO.) (CI) KI'no,,; Tons clum, "'- coUecUon (cis) (Cn) ate IP) (NOs! la) car- orp- (mlcro- " (Mg) IK) (CO.) '"' poe poe Mag- "''' (lICa,) acre-'" llon 1~Ih.OSat HI'>1" day ",- "",- ... ralloo 2S"C) (fIIg/l) ''''I IIlutU

~·U71.. rp,coo ~IVf:~NP.IlR~HIIIM1.\,n:x.

W",~l Year 19S5 7~ Mul"II.J<', flo I'. l~'>S... IS) I 7H H~ ~'17 \~4 "', I.') O. ~6 H90 l,f2 1160 1% 6(,6 17 )700 Mini"",," •. hlly I,S5 SO 22 121 '"I~O 1'10 ?ll'l 4.:5 .11 /06 .% ~1" 28B III, J.I !l1,0 1.9

Wu"" YoO" I~"~ ,., .!~ ~490 1]00 M~K ~.l I\.'xl.."", ~",It5~, 16J 186 89 I.:; 1.I'j 101 8,0 1890 10 !Q I1lnU",., Cl 49 m'" '"17'> '"' 1,19""' ).6 .7U I~MO I. '" 4WI j4" ',,0 2100 8,0 Wo'", Y","e 1~~1 ""xl",,,,,,, l'\:Ie, I~H,. l6~ 21S 107 I','" IIHtI 1,1 .11 1210 4.1~ j420 '!I~ Il~} 9.8 48"0 I,~ MinI""",, t4ily,. 78HI ~~ 20 '"''" '" '"'00 ''" .11 O~ 7'11 1.110 '>'>611 lq:l l'lb 1.1 1160 8.(1 W","" y,.,," I'I~H M"xl ..,,,., M,H. lt58. 211 182 88 'i l~ 7 \ ~1 ~MIII 1,.,'1 14~O 81M ~IO 8.~ 4010 ~,! ,., ~" 1'11"1....", ~epl. l1JO 'i8 to '"'14') ~~ ,U ,C5 366 50 l'lJO IMM M 1,5 "I~ 7.~ '" "' WH"e Y"nr 1'159 !1axl"",,,. f\ilr, \959., IH7 IH H. '>1/ 1/1, 1,% 2,' ,27 ?480 \,17 17\'1 177 ~~q ~,I lu(m 1 9 ~"I't 8~ 1~ "'" 2,5 .10 60J J06 111 3.7 !JIll B,o 1'11"1",,,,", I,JJ '" "" '" ". 1.0? "" 1I"','r Voar 19611 I'\;\xt",,,,", .\pr. 1960 , 19~ 16~ IH 16~ 1,7J 2.5 ,I', 1)70 1, I~ Il4(J 711 ~9~ H.n 11>40 1.1 MI"l",,,,., 0.:<. 19~?, IMO 87 lH I i~ til l~, 81<2 I, I) J7JO JlO lOll l 7 \J80 1,1 '" "" '" "." II 1I,,0r Yenr 1'/"1 M"xh'lJ". Apr. 1961 .• !Il La l}i, 7/,0 tJ20 .. n J~5() 4,1,9 14'10 lOW 'lib II 5 I~O 1, ~ Mi"I"J1'. Ju"". I~O'"" \01, '" 16~ l6fl 44b ,., UOO I,ll 2~JO ~41, J 12 ~.I 2140 7.9 '" " '" '" '" \oI""'r Y.,nr 1%2 MaxI M.ar. 1962. 11.8 ,., in )IH l~lJ 981. I. 0 ,21, 2660 1.,,2 ,~" alO ,01 >I,) 1.150 7,'1 Mlnl.,lJ sope. ,,, l;'H 164 '")00 :169 l. I ,jJ 1080 1.',1 1,88 H8 l"I, ).1 1750 8,0 '"" " Wnt~r y"." IQ~) I\1'KJ"lJlIl. Ve<. \962 .•• ,"' ~~H 1O~ '/1>8 lHO 7.', 2" BIO ·',.81, 1>110 I1)MI 970 fl 51711 7,7 Ml"I",,,.. , (,,-,. 1,96 '" '"II') !9~ ~.I, . II 9~Q I, ,9 J:!70 j~4 1% 4.2 1',$0 7.7 '" " "" '" W."",· ~"or\QM

~1:, 9.~ H.llxl",~,",M",'. 19.." m 16" ('III 1/,6 IIIl,U I.l .2" 2/)0 J 11 11'1l 8JO 710 I,Jao 1.5 1'11",.. ,,,,. S"p" l~90 " '"" " '"' " I ~~ 1.7 ,17 ~/l .1>1 4"1(j ".1 Illi ~.4 ~4\ 8.~ tj",oe Yo"r 196~ i'l9xl."",,,,. Apr 196~. 7', ~';J H'.1 I. ~ . JJ ~2'JO 1. Jl II~O ,,96 5

4 l ]6-'>0 A.O '" """ " "" '"'"' Wot"r Yon" 1966 Muxl..u,", ).\,Ie. 106(, 125 1',1, n "07 1\'1 1,21 IHI, 1., .IH .0',0 l. N 0~2 6)< ~~1 l.9 H)O 8.0 ,~ Mlol .. 'm. Ap,. 1,1,:0 In 1/,1, U 1'59 9(1 Z7n 1~0 ).~ 1100 8.0 '" "" \I"'H Y,',"e !'iol " '" Maxi . !-\.Jr. 1~61. ," 1.39 ilU o . U I~IO 1.68 bJl 4116 I." nOll 8.0 I'Ifnl .." .. , J,dy" ., n !~I '"16~ '" '51, n,K 7. '> .1, 10~0 1.41 J61 232 ~.O 1760 1.1 " " "'" \I.lCOC Yon, 1~6H MI.. I..lJ,", Ape. 1968. ~:5H MI, .6 .21 2)M) ).71 176 601 8.7 3760 8.1 a~ ,~8 II~O MIni .." .. , A,,~ '"n '" DO '" '" J. I .01 719 277 146 l.b H.I " '" "" • 0 ··u. ~o.u :."

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~_1,41',.1'f.C(~~IVl:~Nf.AR COM~:T(lCK.TI:X.··r,,,,, 110,,<.1

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·68· !;,bl. 7,·-~"..... rv of d", ..icnl ""dys •• of Texa •• Uea .." I" ,I,. Rio Gra"Jc b".I"--C,,,,"l,,,,,,J

(lleou1," 1" .1l11~tu... pd l11e' eKcep' h Ind1c,,".d) D1.11.11olvedIIOHd.II Hardn('.llll Specltl 01- aB CaCO. C~- ""- COrl- Date M,~ C~- M.. - p,- dlum car- ~'Juo B,- duct- ~" Sodium t."l.ll- Sullate Chlurloe N'- Ml1l1_ C~- ,I l)j$cMrge (~~~)clum "'- "",- ride irate! 1'on8 Non- ..- ance pH (Fe) (Na) ilium "",- ate (SO.) (CI) ~'·I"n~ Ton.ll clum, colll'cUon (Ca) ,,= (F) (NOJ ""(8) car- orp- mIcro- (d.) I" . (Mit) (K) ." (COJ p", p" P'" Mag~ tJon (HCO,) acre- bon_ mh09 at Lll(>r do, ratio 6 I~t "'- 2S C) ("11/1) .1= of. 8·/,580. klO CkANU~AT EACU: PASS, '"',X.

Porj~rt J.,n. _ S"I" , 101R Ilax1Jllu... 11.11 1938 .. Ir,~o 212 II>~ 0 JlI '12~ 0.11 I lAO 1,1,0 ~200 4',1> 4. 'I I !'IO •. 0 HIoJl""... Jldy,. ,~OO '",., ,., m , " ,IJM '1'1\ IA200 '" 510 '"" " " " , " '" " " .." w"'~ L, .~', 1110 1.,1 6140 :l12 <~ I ,.. 11\0 .." CD Min, .." .. , S~pt. 8')1,0 .,'" '" " "'"I')H 4'H .., 11'11!(1 )11 ,!,j H') R,O " '" " " " "" Wotd y,>Il' 19',5 " " ,~ KIlx!"""., 1ltI<. 1941,. 21SU d 14] 2/6 1.9 1030 l.i.O ~980 ./,1, 1,,1 1630 '-, ,I~I .,. ,~ Mini'll'''', July 1945. 61»0 "' .. I)'j " '" '-' " ... llHlIl 240'" lit :' 9'W .., " ". " '" '" WH~r Yo'" 1~46 fl".I .." ... 11I«. 1~4b, 11~1J :!\I '0, J';I 1!.7 . ~] UIO I. b~ ',8~0 ". 10', \, ~ 19W ,.. Mln!",,,,,,, J"nn. ~'I()II '" '" ,." 14!l " " .1'11 .i,1 4HM! 1,6 \51 "" '" " " " "' '" '" '" '" Wato< v"',, 19r.1 M".I"" ... Jan. 1947. 21>111 ., 1~7 .., 19" ..~ .10 H~'I 0"" nu j.H !:l4Q H.O S~pl,. ,,, 111~ ". ~ ,1>11 .. Hlnh,uOl. S'170 "I, " ," '"It9 ,.. I" 441 '" 71HI , .," " " '" '" " ~'~'"'Vea' l'14A J~". , ~j4 .1', f11f1 I,>JO 'J.4 Hub." ... 19i.8. IS60 1\11 17/' ,," .1.1 Ill, J.b IJ:l11 "." Hlnlll1U". JUl1e ..• t~I,OO "' '"'-' ,., IM4 7~\ll '" , .0 JOI " " "' " '." ". " ." '"' " •'."or Yo,," 1~49 !1i,xl,.u., J.L1. 19/.9 .• , IJI ~.I) I,ll!> JH9H 12JO 18S0 n ,., ... m '-' H1"1",u,,,, A"~ ...... •. 81>1.0 00 "-' 1 ,3 0 '" .., 0'012 ,. 9)QO '" ""., l.i_ '"' " '" '"' '" '" ." '''' 0" .." Tahir 7. __ S"..... "y "I ch""lcal analy~,,."j' I"",," 'l'''''''" I" don RI" G

,." ..._-- .-----,,-u .-- ,_ .. _-_._.._-, . . --.diCG'Od) DIssolved 8011ds Hardnciia Spectrl as CaCO, So- BI- con~ po- C~- Dale M'M C,"- M.. - car- Fluo NI- Bo- dlulll duct- SllIca ",- Sodium !:luUatc Chloride 111111_ C,"- 01 O1scharge "0' clurn "',- "",- ride tratc Tonn Non_ ad- ante pH (SIO.) (Fe) (Nil) ilium "",- ,~ (SO.) (CI) I-!rn ..R Tons clum, colll!'Ctlon (ete) (CI'l) ,1= ate (e) (NO,) '"'(D) p", car- (Mg) (K) (CO,) pO' po< M>\g- (fiCO,) Ill",' llcre- ",- "",_~'PWI"O-lion mhos at fool d" ,.. ratio 250C) (",~/l) ,1=

8·458U. ~10CRANO~A1' I!AGI.~rAS~.1'~X.--r,,,n'In,.,.eI

Wn,or V".H Iq,U ]1.>,,1""'''. Jon, 1950 •• UJO 12. <0, '>l ,. O.IS 1).~5 SI5C m 1110 ... Ml"lra"". 0<:, 191,9. ., U I'• In .15 ",y ... 6330 m u 7',2 ... YO'" " " " ," '" " " '" '".', " WntoT Yon" 1~51 lIlo"i_.I·eb 1951. 1610 ll) 2S0 In I.. l .l> ~. 1.1'> 36&0 m L:li,O ... !'Il"t ..".,. J""o. 2630 15 " .. '" " I., .1l1 .M 1190 2:14 '" "l.l " " '" " '" "' ", " '" "'" WHOT ~".H1957 M.!IXIIllU", l'eb 1952. 18~ L. 19 1020 35) 'OY Y.Y IlI,O MI"loou,.. M.!Iy.. noo"" -- '" "II '" 41~."" ',4~0 I., " ", " ." "" '" '" W.,", Yonr 19~J y~". 0011 140 .., 0 l. 14 LJ60 Maxloout'l, 195) ...•. _. ", MI"IOlU". AU~ ...... 1200 .- .., II '" "" 1460 '","" '"l.l ""yO, .. " " '"" " '" . Wnt~r YonT 195', Mlll",u,., H.or. 19 ...... 1+39 121. _. _. na .~a '00 Y.' LI~O .. .)'/ J4}()O 42~. MI"hou,., J,"'e 41000 '"' '" '" " '"' P~do~ 0<-,. 1951, • J,,,,,, 1955 ~, ~~b. a~ II ~41. HAD .18 U I~~O Hs."I...... 1955 .. 1070 _. I.ll IH"LooUII, J,,,,,,. LI~O '" III 0 -- 110'" -- .Il 145U 11(I 'I.U --- '" '" '" ." .... 0 ...::..:

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Reault. lu ..1111 ra"• o. 11,er ,,"cc t u In,Hene") 018801'l'ed solids Hardnll8s Speeltl as CaCO, BI- So- '00- Datil C.u_...- Po- ear- Cu- dlum duet. ,~,~~I Fluo NI- Bo- • Iron ,,- Sodium tao- Sulfate Chloride .111111- ad_ anee of D18eharge (SI~) clum "",- ride trate TonB C'";,1 pH (Fe) ,1= IN~ slum "",- (SO.) (Cl) '0' grQ"" Tons colll!'CUon (Cal ,Ie ," IF' (NOJ IB' p" orp. {micro. (ctB) r' I (Mgl Ix' (COJ pO' p" ',\~;~I~:;: (nco,) acre- ne. bcm· tlon3f~hOSat liter do, ratio 25.C) ("R/1) fool IIluw ate

6-1.613. RIO CRANll& RF,U'IW PAtCON DAM, TEX.

"a'e< Y"o. 1956 Mul"",", ,1,"6. 19}~. 421 .. 1',1 no 0.26 m 00 63~ J08 188 3.2 1170 8.0 Hl"i".,,,, Oct. 19}5. lX.)O " " '"" '" '" '"'" 1.9 .10 1d2 ." ?lJ611 Z10 102 1.1> 1O~ A.O "Ole< Yeo. 19S, HIIxl"".., Apr. 19S7. na DO ,., .n ,., 1.07 IA6 3.4 1220 H1n{ .. ,.., J"ne. 2170 ?J. m '" I. 2 .05 m .1.2 lJJO''" '" ~5 1.3 506 1.9 " " " '" "' " '" Wa,"r Y""' 193A K>!xl.. ,.. , K>!y 19~8. 4210 .. 1/.) .. ~400 96 t.O )40 1.9 Hln1 .. "", O.a. 1957. 3220 55 1/.0 M. ." '"no J720 '" ~I, 1,1 607 ~.o " "'" " '"" " ." ." '" WOld YUt 1959 Hul .. ,.. , A"g. 19W. 19~0 ,. . b ,I ~ 511l .. 26QO BI 12A 2.1 784 7.9 H1nl"" .. , Nov. 1956.. 19l1Ol) ... '".. 2.5 .10 J/.7 .1.7 17800 1J I.J 551 ~.O '"" '"" '" ""' '"" lIotor YUT 1960 l'Iul"", .. , .l"ly 1960.. 3120 1,.7 ", 11.8 .. .12 ,,. 50~O 2~J Ql8 1.8 Hlnl ...,",. 0.,. 1959. 1580 m ,.. 1.2 .16 " 2150 m '" 79~ 7.1 " " " " '" '" " '" '" '" WOlfr Yur 1961 11II"11,,,",. NclY. 1960. ,01 ,.. ,6 ,2~ ,,, ZJIo 1:16 ~.~ 6JO 6.0 ,~ ." '00' IoI1nb.,,",. Sept. IQ61. .13to " " " '" 11,9 " " ... 1.550 107 2.4 HIS 7.6 '" " "" '" " , '" \latH Y.... 1262 ..... ",-"1,.",,,. Sepl. 1962. 612 ,. ", .b .11 ~8] ~]O In L.9 91~ 1.7 N fllal,."., Jo". 4SJO " " ,., '"m '" '" .., .6 .16 '" "' bJ30 230 120 2.3 831 7.9 " " "" '" " '" ." ~"t"rY.ne \9~) IoIoxl"",.., !lay 1963. 95\ .. ~24 ". b.2 25 .. lXlU 167 3.1 1110 '1.9 MinI,.",., Nov. IQ6~. 839 .. 13/, .6 .19 ".'" 1110 '"' lJO 2,7 n5 7,8 " '"" '" "" ", ." '" lIour V~Ar191\4 MnU"" .. , Oct. 196J. loon 111~ !~A ~OH . 6 . lJ ". .. IHO t41 136 1.9 95J 1.8 Hl"l_, lOb. 19M. 7J9 "' " .. 11.0 '" .b ,11. .n 1160 IZH 2.A 9JJ 7.9 " " '" '" '" '" WOUT V~U 19M IiAxl",,,lO, 31411 1~ , , 1)1 no 4.~~ .62 4590 200 81 2.1 725 7.8 July \905.. "" ... Aug.. •...... •. lJ60 '" n '" " .1J .., 1670 .., All 2.2 no /,6 Mini ...... Nov. 1961...... •. 1/20 ,., " 2,5 .15 w, lb90 b5 1.7 579 7,6 " " '""" '" "'" '" ." '" \/", .. Y~nT 1966 ,. !-\;>xl_,._. Apr. )966 .. "00 .. .. ". 1.2 .IA ". ." 2140 230 110 2.4 829 7.8 1011"1",,,,". Nov. 1965 .. ,. '" "' .b .16 10110 210 911 2.) 167 7.8 '" '" " '" '" " '" ." \lnLer Yo". 1~b7 !-\;>xl_.,,", July 1967,. 2260 ,. ,., .. .0 .1) n 1580 2I~ 121 2.8 897 7.1 MI"!",,,... ll1.1 8.0 loll"llOU". 0"0. 1967. 1000 " " "' 13','" .."" 1.9 .13 1.56'" .., 1230 % 2.1 7J5 1.7 " " " '" '" " 1..,.. thun 0.4 ..1I1Ig ..... per lltet. ,..;.....: .,,.

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8·1,655. RIO C~hNDEhT RIO CRA~n8CI1'V. TI~X.

fe"I"11 I'ell. ) • s"" .. [] 1~31 K""i .."",. Ap,. b, 19·H. 6110 '1'/ I'll , 2n .,.8 -- 11)1,0 1,1.1 1nOll 1,1l1 11,6 I,.J 1580 KJnl .. ,,,,. ~~pt. I). ?lIjl)(] " " " '"''". " 1U~ '"I,~ U 1,20 .J) 23200 2:;'1 W, " 620 ~.\erXea' J9J~ ~"J.. "" •. hm~ 19!4 41,.:,0 1)'1 ~O~ 172 ,,, 11.27 \1,00 1.90 17500 ~71. ")~ ),1> 211>0 I,)uno y', ~.Il , '10 , .1Q& 4&BOO Milll"".,. On. ), 1931. " "" "' '" '" '" " " '"' " '" ." Wa«" Ydr l~n H."iI",.,. i'\<,c. 1~'l5. ~loll .. llJ 1~I 0 141 t.~ .2~ 1010 1 ',0 5~BO 1,0t, no ,, 1~,0 , .~jnhu.,.S~pt. ~?61)(l , H~. .1H~ \~ JO~OO '1-1<1 IO~ . ", " Iio '" 6JI ... " '" '" " "' " W.. ", X~sr1936 ,I M~KI.",",.r~h J~:16. 'CO I'U 0 ," O. , .11 .., 1.20 7)60 lJ40 0,' Hinl",,,.. , sup' 2tl1.00 l'l u.s , ,yO .1,& IS600 ".11,7 U .. "" " " '" '"'" " '" " '"" '" WHee Yua, 19,1 ,,,, ~'Kl"",,.•• Ipr 1917, . 1990 190 14? , lli, lUjfl I."IJ ',,30 J'n ~16 1" lblO ,~ Mint"",",. 0..... 19J&. 10800 YO '" .. , " 1~900 n2 '1-.~ I~I ".J'" " " "" " '" "' "" ~HelX"a' l"l8 H.'KI",,,,,,, M'lr. 1~'iH 2940 I(~l ~O! IJ4 HI, .>0 1100 1.4'1 81-10 40" In 4,1, I,'J Hi"t""",. Sep'...... 15&00 " ,,) " '".. "," .tl ·146 ,wOO ," I.. """~'!H " '"' '" " "' "' " '" W,,"~,Year l'n9 i'l~~Ir,,,,,,J"". J~J~. )1)0 )(J I ',H 16~ 0 ,1,(, 20/, 1.2 ,18 8'11 11>20 ,.. 2,') H D80 H.I -.. i'llnl"", .. , S~p". ',770 "' JJH , 1)4 2.', .13 4lJ " 6010 no ,0. 2.2 .., (J) " " " "' " '" W",~rXr~r121,0 1b~1"",,,,J" ... 1940.• 2,,1,0 % ,., 0 ~68 m U ,., l.Jl &Y,O ,., 231 1,.0 1510 ,,~ HI"I"""". June .. ,. '" 0 .. 2.5 no %20 YO U ~25 B.' "' ..." '" ".'" " ." ,,' '" ." II;,,~,X~.H 19'.1 lIa~h.,,~.J,dy 19'd. 9250 11,9 , m 21', o , ," Hl6{1 I.M 1~5(l0 1,52 no J 7 1510 .. Ml"i"un, Del. IW,O 1&10 '"~5 " '" on 0 ,,; 1.'1 . J~ JB~ .5! 19LO '" "' " '" " '" ." '" lIu'", y,.,. 194~ , Mad.""". Ilftc. I'J41 ...... ~190 )1,1, I~I, , ~1I, , .1.5 1900 t,59 JlgOO 1115 H 1(l10 .. H1"1"",,,", S~pl. j~42. .10&00 " ll,9 "" CO , , I,I'J :\1,600 111 '"" " '" " '" " " '"'0 '" '" '" W",,,, YO"' 191o'l M,'xi..."., I'ab, 19',), n80 nl I'll '.1) J13 1/70 1 71 II~()O '.11, , 19 ,0 '" ," ". ' ,", 5';1 ~j200 2101 . Kl"1",,",, OCl. 1941 1%00 "" " 15S U "'0 ,. '" " ". " " " " " ". " " W",,'" Y,·", 1944 I!"~l ,,,,, hpr. 19',4. lMIl YO ~17 Ill. II ~II "~M) Hh , , 17911 .,, .. ." 17" h,,~ '" Mini ,,,,. ~lIWO " .. .. "' U ,,' '" I,; " nH 18~OO 1;(. ... l.& '" "" " "" " " '" "" '" ...: ..

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Hill GKM~rAT MISSlUH I1JMP1NG PLANT. NEA~MISSION. TEX,

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R".uJl' in ",Jill"ra,," 'r lIler He"" .1" i,,,Hr:ou',I) Dlllllolved IlOltdll Hardneee SpecUI m_ aScaca, SO- con- M",,- p,- Cu- dium Date Mom C>I- car M Fluo NO- Do- ducl- SUlc Sodium b pO' Mag_ tlOII (HCa,) acre- """,y "',- mhos :l.t II t"r 1001 ,,- ratio 2S'C) (midi) ulum .t,

8_3635. RIO GRANIJP. AT I.I:A5BIIRG DAM, NEW MUlm

Ped",1 J"". - S"p'. \939 Milxl"u.. , Jan. 1939 .• 11'1 , no 0.6 0.16 ... I. IS ,,. 115 ~.I W",~ "00 Ml<,I1"'..... Jul~, " ''" "" 52l .n '" ", " " "' " ". " " "" " '" ""' w.."," Vear 19MI Md"" ... Ja"" 19',0. lM , ., 1,60 1.11 .., 1()OIO ij.n .sr, ." ,,,'" 111"1",,,... Apr "" " ""11'1 , '"!J9 '" '" .., ,. 2~8 ~Id Ju~c. " '" n1 " ., " ,,."" ILl 1.'"I '" " " '00 '" " "' ."' '" "" WAlfr X~H 19',1 Milxl.."",. D"c, 1940, ", 15~ nB , 329 m , 9/,9 1.29 ,.. W, l,l, \lBQ ., ~Ul ,. f.l!nj"",.. , Sept. 1~ld D n , ., " .Hi <, J 1.9'" " '" '"' " .'" ." '" ~Ola ~."rJ?42 i'Wxj,.",., ,1"". 194~. 119 nll 241 , 172 I.QS JII, l:l', ],2 116Q f.llnl",,,.., .1,,1 y '" " D" " '" .. .1'" ." ""I.B 1~1 , DO'" '" ., .00 '<19 '"Iqlj ." A"g. " " "'" " '" "" '",." 11>0 J.]I ., .W 1>19 ." .'" ..". ii.p'...... '" " " " , " M" , " " " " '" ." '" "' ~.1tCTVoaT 19/,] MdLtlJ'". J"n. \9/,) .• :1.:1.8 , 11,8 ., I,ll! 11h D" 11'""1 '" ." 1,1,l 111"1.."". J"ly. " " , l:!9 " I.') .M '" '00 M " ..,"" "' " " '" '" " "" ''" \/atM Vo~r 19M, III0 ,., ]1,9 00 ", D" '" " '" '" .. ." I,B~ A~c. U , IlK , "" .tt .".M !:o n !.l ,."" "' " " '"' '" '" '" W",.r Vdr 19',5 !'Wxl"" ... J"a. 1%5., 1111l 114 HI , <'I) I.lJ JJ8 lHO "Unl"" .., f.l.,. "U ,n I\q '" 4B~ M nQ '"n ,.1 1~l "" "' " " '" " " '" '" "" lI,uer t~.r19lo6 194~. Ill) ,41 .. lH8 8'\B 1.14 lSI I:.B ,., 124Q l1uJ""",, Jo". ." ." I,ij~ 1',~ f.llnl"",,., f.l'" •. ''" "D ", , D' ". ... ]12 1.2 B.1"" l>I,y •. J:j 112'" .tt'" 1,55 ,61, to" 1.1 n" " " " '"' " '" " Wal.,' YeaL 19~1 ~. / .0 "8.', '" " '" "' " .'" '" '" ". ." '" W."", X.'", 194M K;.. l"'r>, ~"h. l~l,a.. W, 21< I/o! , no lS" l,·1 Il.lQ ., .'" ." ~21, 111t11"",,,,. 5~PL ", ", '"lau , ", '" " '".,07 ."' '"" l.1 '0'" "" " ." " '" .""• ..; ,.; "" - ~ -, -, . .~ , ~ ..0 ·u - ~u -. ~ ~: - - - ~

;

- ~ -•

.- - ~ =

:5- , ~ ,

- 83- t.~l~9.--~u... r1 "I d\dl"'d U".lyid H .~le«e"du. on H"x«~nHn""" \" the kio G",,\~.1.""1,,.

\x•• "". ,,, ",,,,,~,..... I'''' la.r dO"p' ." '''"Ha,ell/

Dl8so1ved 8Qlld~ Rarduo8s Spe<:lfl BI- al: car- (micro- (M\:} (K) (COJ po> Mag- lion (IICO,) acre- 00'- mhol:

X_l71) ~In cnNClIn'J AT CIIGIlILLO PARAIJO, ~HIHUAI!U,\

l'al,," Jau. - S"p" I'J41, ~~J 1'\;1<1",,,n , Au~.. 194~. 311~ ~l\ 0,1', 0.9 1+ 7H~ 1~1i 2,' ." ~ fll"\",,,n., 6, ? W '"lid 0 ,e; 1,5 HI"" . , 1',1, '-, ,.. Sept " " "' " " " .'" " '"' " OI"L~'V.al 19~1 l.~ ;aI, l'I.xl",,,,,,, .1"ly 1~47. III \41, , .21 ,"0 1112 2,8 1100 I'Ilnl",,,.. , ~np" '.0 ll,~ , "" " :.I. ~ )81 '" 1.'1 ,O:e "I.'j " "" '" "" " " "" '" WaC"" V"al 1~4i! lI"xl.,,,",, Ape. 1~4B.. 1<7 , 174 m "00 ~51 124 1.1. 10~0 ,., ". ~, ,~ H;nl~,.. , Nov. \~q. '" 0 'W. " ..." .Il" .n '-" " 1&0 , ~, m 715 7.') ""'t. 191.8. " " ".- '" '" "'" '-, ." ." '" '"" '-'" w",,'. V~~c 1')4~ 11)40 Mnxh" .. , '""'1 19~9. 10' 10O ID , ,.. ,.. .1.5 '01 J01 ,., I.B '"~ ~~8 .., 10M) J~,,~. " ll~ D~ , >II M '-' '" I (JI '"lI,8 '-" ., I,I,~ . Ill"hi~ ." ., 61.0 I., .. , l',ll. '" ",.. 1M , '-' '" '-' M,~ .., 5', 0.> , lI,~ 2., ."10 .M '"III " l.l M' " ''" ''" " " WaL., ~~B'1950 ,., \1~ n~ 1\7 U ~I,6 """xl..,,., A"~,I~',O. n ', 10 0 10 U .10 24" '-" ,., lI,~ \I,q ~(}2 .. Hlnl~,,,.,,)"ly. J. J M "" " "0 '-' , " " " " '" '" "" ~Ol.r ~,.",1~51

~I,IJ 12(] i'l>xi"""., Apr. 1~~1 II/l 170 oJ II .n J.3 '-" l~~ ." 1'1.6 ,., KI"I",,,,,, Ju"e., "00 " '" "W L:! .21 '"m .n :e.t> '" ~ " "' '" '" "" '" W"ta Y"M 1~\1 9~~ 311, 1,.2 11,20 H"~i...",. Apr, 1952. 'n 0 M. II', 0, 10 537 .n" ,,. 1,1 122 '1,8 III "I .. "•• ,I\lly " " '" " '"" '" ,>/"",. V"", lqYJ 3]1, 1~80 1I,,~I,"u",.Apr 195'1" 2W, I~< , 291, l77fl n 21.2 6.1, ~cpt. ,. 0 M. ." ,~I, lW, l.O IlII,h""". '" '" '" WIlt"r V~," HY, ~la I,,~ 1I;,.I"u01, Apr, 1~51" HZ ,0> 0 225 \ 2~0 n 1860 ~l~ lXH 1.0 1l1"IIIU", ~"& '., '" 0 " .10 '""" no 1',,1)1. 9,--5"_,'y of ol,o.. [r~l~n"l.. u lOt oeleo'd .Ile" "" M."xlc~",t".I"--I;"",I""od

I', •.~'U>L' ... ~ 1111.... /;,a~. '"" "C''> ,,~crp' an 1",1l",,,,,.""''') ') " DtllBolved lIQlIdB Hardne811 ~e111 CaCO, B1. as So· con~ M... Po. Cu. Date MOM CN' car- f·luo NI· Do. dlum duct- SUtea ~oo Sodium boo· Sullale Chloride JUlll- C",· of DlIleharge clum ". b.· boo. ride ualc Tonll Non- ... ance plI (SiO.) (Fe) (Na) $Ium ate (SO.) ~l'O"," Tone clum. coJlecUon (crs) (Cit) ,,= (Cll (F) (NOJ '''"(D) p." ear- orp_ (mlcro- (Mgl (I<) ". l (COJ p" p." Mag- (BCO, hon_ I~I 111.(,,' acre- doy llon0 hOlj at 1001 ". raUo :as"C) (m~/l) slum ",

~-)JJ~.RIO CONCHOONEAR OJlllAGA, ClllHUAIlUA

l'd'l"d HI) .• sop' 19)~ >!axl",,,,., K.ly 19J~.. 1',9 Ito 11,11 29', 1611 ("G 1270 HI"I.", .. , S.P', ". '".., "11 "' '" " '" '0.1 "":!J2 '" .Y " '" '" " ," " '" '" '" 11,'00' Y(·"r 19lo '" " Maxl,.u.. , Moy 16, lQ36. 112 ". to, n~ .;t m 221• 1210 ,. M.l"I .." .., 11, l'I1~. 15 , l,l)<) ,. ,,, ,. ad. " " ' " "" " " '" " " '" " '" "" Wa'd Y,;", 19JJ " " '" !Illxl",,,,,,, A"~, I~, 19)7. 1lI1, , ", .1 .11, ))1, m u lHO ", 1'11"1",,,., J""e Il, '" '",,' '" 01 "" .. "":l~3 '"J,~ (,ll. 0," '" " '" " '" '" " Wo,,;,' YeH 1938 "" '" l'I"xl"""", I'\.'y 19)~, .. DO , no n L~ 2QO lll~ ,., 1 Ill) ... U~ ." I~O Hlni""", Sept" ',1, "0.' "" , ",, 0', 119'" '" "' " '" " " '" '" W",~r y.u 19)~ I!aXI,.."", J''''e I~j~. .- 1115 , 29', , 1.0l ~.6 1039 ... Hil" ..",", A"K,. .... YO 9,1, lSI, , 1',6 (,"i.b "i.1"l 1./' m o. , " '" "' " '" '" '"' '" '" "" WH~r Y~H L9',0 " t!ul"""o, Apr. 1940. III, 17f, , m , .,. .n 271. 129 1069 8, :l HI"I .."." A"g,. "' "11,5 ,", ,, D '" 1,'1 II, "L', m .., "" " '" " IlatH Yea, 19.1 " " '" " 00 J1u.l.,,,",, Apc, a"d K"y 1941. 1/.1 In 772 1.05 ',00 :l8b L> 1910 '0 '" ." 1~1, 1'11"1"",",, S.,,,,. "" , "YO m " " 2.'" .',0 1\.1 U I;H " '" '" "" '" W,n"r Yo"," 1%2 " " Haxllllu"" Kay 1~42,...... Inn 1)(, no , .1 LOI HO 1I~ 1160 l.~ 1'11"1,.".,, S"P', •. " '"',5 "... .00 ~h .J7 l"b ,0 lH ,.. '" '" " '" WIH.r Yo'" 1%) '" " '" " " H,nl"',"", K.'y 191;) , 2/01 1 .to oM .'!! ~IO ~.6 9~9 R.O 1'11"1"",,., Oct. 1941, " " " '"Il;!, , ", " U J',l ./,8 '" U 51l. ,. " "" ."' '" " w"ar Yo"" 19/.1. " " Kn"IIO0, "' " '" '" " '" '" '"" " ~",~r Yea, 1946

19~~ , 2r,~ M"xl,,"'DI, Dce. .. 'n ". .n Hl l.01 122 2.S lC10 MinI",,, .. , "' J4~ 001"" .... ", " !48 0 to" " ".. ."7 '"'1M U ~14 ",.. " "" '" '" "" -."

c , :~ ~'

0< , H - ~

,"

- 86- T"bh' 4.··S_'y

(~.. "I •• 1n 'lilH .... r Ill"r .. c" 'I". I"dle., .."

Dlleolvlld eoHdI lI~dne81l Sped!l .. CaCO, 80_ Po_ Cu_ '00- Date M.~ CoJ_ M.. - ea.~"'- dlum ~'hlQN'- duet_ SU~~Iron ".- Sodium boo- Sulfate Chloride .0-1I1l1t~ CoJ- of DJ.eeharge elutrl ...- b

~-J1J(l.RIO CO~CII()$~~.utOJ1N~GA,tlIIIIlJAIlUA··I:""ll""uu

loin•• hur 1'1'9 "".'." •• I\llr. 1959. ,~ 0 D' "00 I. /I /.. 2 1110 19~a I~'l 1~1, ". IIlnl." ... Oe:t...... '" , IbU .:,g '" ~. " " " '" 101.,or Y••• I~MI 110,.1_. oc•. 19~?...... 0 WI IIll} I.H 2U ... 1560 A"II. 1?60 '" .., 121 .., 111"'_. ...• '" 0 ." '" .. ... W11¥' Xur \?U " " Ie.. , .... AI". 1961 .•••••.••.•. , 1.41 .., 1490 ".,~ ,,',,1_,July ••••••• '" 0 '" 1.. 0.1) "'" .., '" '" ,.. ...,., " " '" ". ". '" 101.,.. Xnr 191>7 " '" ""'.1_, ""y 1961 .•••.••••.•. ... 0 1100 1.4' ).1 1610 1111,1_, S.rl ,~ ~ .., ...... '"" 0 '"" . ... '" '" ". W••• c It.c 1962 """'_, ....,. 196J ...... ,.. 0 UlJO 1.40 ,~ ,.. .. 1470 111,,1_, Sa~'. ,,, ...... '" 0 '" ." U 101.,•• X..A( !?f>4 " " '" '" '" "ul_, Apr. 1?b4 .... 0 1,4/ .., ,~O "11'1_, ~"p,••••• ,.. 0 " ""'n, 21/, U 1020 ...... '" '" ". ." '" m'" 1I•• or X.... 126' 11.. 1"",., lid,' lul>~..•.• .... 12) 0 1120 I,~J ,.. >.> h80 CD 111.01.... 8,·1" •••••••••• ...... 'D '" 0 '" ,," ".'" ... HIlIO -.J '" ." lIole, W.!' lH6 " " ""a.I...., Apr. 19M. m 201. 0 110 lI)O ]8/1 1.. 1 1(,10 111,01.. ,,,,, ~"I'I, ',0 'IH1 .51" \9/, '" J.l '" " " " '" o· ';'

.00 ~"'.T

; 'i .- "

.,;;..:

, 1, = j 7

- ",<:II: ,;: i! 'g~~ ~:ti

,88, Table 9.--Su_ry o[ eh.,.,l"al analy"e" at ocl"etud ottOI <)tl H"xl""" Ot'''d1l0 l" th~R!" Cc""d" b".l"--Cut1,l,,,,~d

\n~." .... " ~ .... ~ ...... "A"_~. HW ...... ," ""., Dissolved IlOHds Hatdne86 Sped!! ati CaCO, M m- ""- '00- Date M.~ C>I-... Po· Car_ Cu· Fluo Bo- dillm duct- SUlea SodlullI lall- boo· Sulfate Chlorlde ..- 1111U- 01 D1Beharll'll .,'" dum boo- ride In.te Tonti ad- ancl! pll (SIO,) (Fe) ". (Na) alum ,., {SO.} (el) "0 !ll'nm'" Tons Chlm,C'\INon- co!leeUon (els) (Ca) ,,= 'F) (NOJ (0) poe Ol'p- (mlcro- (Mg) IK) "0 (CO,.) Foe p." (lIeo,) acre· ne- bon- tton)r;;hOSat Ill",' M"J"'-ratio 2S0C) (ml{/l) I." "" SIIlW ate

A-4~10.RIO ~"'NRODRIGO N~A~n !IOML, COAIIUllJl--Co"U"ucd

I'"d"d Jan. - S"Pt. !g~O J]I O.4~ 212 .. ""xllluOI, AI'" 19~O.. 00' ", 4.3 0,10 , Sort .. '" '" " '" ," ", ))1 .., " " '"~(!l '.0 Ju,,~ ." ,0, 1'11,,111"'0...... •. .," "..., " '" " '"U "" '" " m " '" " " " "' '" ." '" " "' ~.t~rYO"r \951 V, , Ma"I....", !l ., 442 !In"!",, ... Jon. \95' ...... •. ,'"_. flt"l,..",". Mor. .." '" , '"m " 0" ., m "' " "" "' " " " '" " 1OH.' Y.", 19S~ I'I11X!"'''''', S~!'"Igo;<,. , 111 Ii') .. LO ,0\ Hltd ,,,,. J""e. ,., , .. ,, 15" ." , .. " '" " ." '" " ". lla'"r YOcll' 1955 1 , SOli ""xli ...."'. Jon. \9';5. 8. • .. ., ... Hrl ... 21i .- H.t F~h••. " '" '"" " .. '" H~ 112 ., m Hint","",. Oct. 1951,. "~.1 '"115 "0 " II,) ,,"'" 101. " , OJ '" " '" ~'"rorYr"" 19~fi , ~15 ~,"(1I11'"Fnll, 1956, .... m 0 .. m .',5 ". , '" 11101.,,,,... ~pr.•. .... 'I.B 153 0 m " , '" "0' " '" '" '" 1I,,'.r y,.", 1957 Hoxl ..,,",. Mo.,..1957 ...... " ... ill )'17 , ," , ,6~ Hlnl"", .. , Arr. " 1:14 "S.3 '" .ll '"'m ".. 'W \I,"", Y.", 19SH l'I"xil""'O, On. 19H. , .. m ,I.} n5 , i~~8. , Ml"I.,,, .... h",. " '" " .n ". " '"'H:l A"8· . 0' 11,:1 "0 '" lH " , '" '" " '" " '" '0' : :

1

~:

: :

- 90- robl. '" 'S~r1 <:ofoll."loal a"",lyho at .~Io,.~dol,oa "" H.. lo~nalru'" In Lh. Rlu f. •• nd,· b•• IB·-Contlnued

\n"""'.,, ,u ."" 'Krn,.. ,'... ,'« •• ~.",.. n ","n"' .n! D18801vP.dIIOIld8 lIardnU8 So_ SPOcll1 UI- ae CaCO. ,~- Dato M.~ Col- Mo<- P,- car· Car· }'Iuo NI- Il<>- "',m duct. u,~j~'"M- IUllt_ C,I· of DJIcbarge clum Sodium ...- bon- SuUate Chloride ride Irate Too. Non· ~. (Na) slum "',- oJ. (SO.) ICI) !trRII" Tona clum. ""-orp. ON coll~Uon (d.) (Ca) "Iwo (p, (NO.1 '"(U, pO' car· micro· SlO"1(eo, (Mit) (K) pO' MIIIl- tlQn (II~~'}I(COJ 111"'· acr/l· do,'" ",- "',- mha. at raUo 25"C) (ml'/l) loot Klum .1<

8-~6011.Rln ~~I""llClAf CIU\lIlII GU~IUI£RO,TAIIII\}lll'~~

h!.\"d lb •.• S~rt."U ~-j ","xl.".,""r. I. 19J~.,. In , 1,)0 7110 J.l0 ,.. I~M. ", ,,, 1,61 Hlnl." •. .ruly ~4...... •. "", '" ,.. , "" "", " ." "" ... " " " " '" '" " II.... Y.u 1~:16 .., ~. ~"R.~1. , 1.29 1170 1080 1 JhllO IIooxl••"o,. 19)6. 1'10 "00 I. " '.M ". H~ • .ruly ~) '"III ., IJ'J ... itlnl_ ...... • " " '"" " '" " " """'" ." " Wuor Yo" 1~11 ~pr. I.S~ )1,00 ~.6J Il~O 4210 .. 1".. 1._. U. 19)1 ...... •. ". , IHO '"00 .,, Au~. , , n') 1.1 ltl"I_. 19. .. '"... """ '"" ." '"" " " " '" .." '" lIll •• Y"or Iq18 ""xl .. ,",. feb. 19j8 .. I'll I ~~O ~8', I, IJ )~',C 4.q) 14~O n4n U/C ,. l~_l ".,I ~6~ HI"I .... Sopt. '" '" '" " '".., ...... '" /./ '" '" " '" " '" '" ." W!Ur r.or 19j~ ..... 1.... , It.or. 1'))9 ...... ]14 1,)9 'I' , 1'100 ", ... 211~C 1.R! IHO ll~n J810 .., "Inl",,~.Sep" ...... •. '"", , '"n ,. .n ", " '" " '" " '" " " " '" " WAL"r Ioo. 1940 ~IM) , ,0 )'IH "nx!~,,".Moly 19~0. ,.. It, , , , .u ... m ., 1I1.. 1,.~... rtuv I~]~...... , "U "l", , '" "" ,, .07 '" " '" " " "" '" '" " " '" " Vii .. ho, 1941 ".. I•••• ~ •. 19q ...... 2lf .. ',M '00 0 , 1)10 l.4) 'tbl 1190 I.~ ,,, '" ltl"I_ • .rw,~...... ", In , "" "" '" '"'.. " ,.," " " " ". ." '" " '" W"'n. YUr 12/.2 HUt...,,", ~p,. 1941. 4 ,) 1,1 1, In ],13 11I·0 ,, m , ' .., ". "00 ." '.'I.) 1,76 I .• ltl"I0."" . .r"n~ ...... "i.8 '" '''' , .. ,. ". '" '" " " '" ." "' " Wn••• yur 124) .. , 1190 46)0 6.1) 1110 Ino ,, HSO IUold_, "pr. 1'''3. , II' '00 -- ,... HI"I_, Ju"o ..••.• ". , '" li2 III ,to 8," ] '"" " " '" " " ." '" ." " 110ft! x... 1?~4 I~I,O 14~0 Mnlll,o",...... ~•. 1944 .. ,.' m to, m , 1810 .. 11(1 )9)0 5.H ... q?O ,. , 241 ,., 1'I1"I",u"" ~\IR I,b '" '" ", .J') " " '" " "" ." '" " • '" W",., hot 1~4~ Mald_, "'UII. 19'\) ...... '00 , 11'l1l l.a 2520 'J.)] 1020 ,. J)!O "1,,1_, (k •• 1,...4 .•. ". " to'" 0 ,y, '" • ... .n 1/2 '" " "' " " " " '" '" " '" ", W1

K~."l,"1" nUll 'u". or llter exor t a. !"dtr,,,~d DISSQlved solids Hardness Specttl aa CaCao Mag. p,- BI- "'- con- Date C,"- car- Cu- Fluo Nl- B,- dlum duet. M,~,I~~I,,- Sodium Sullate Chloride 1.11111_ C,"- DJBcharge SUlea 1I"0n clum ...- "',- ride trate co, Tonll Non- pH (Na) '00- .~'.;0.... TOM ""- ~" collection" (eft) ,,= slum ,l, .l, (SO,) (el) ,p,(NoJ ,e) clom. car· orp_ micro_ ,,,., 1'S10"1'F,' (f.1g) IK} p" '" Mag- tlon (HCO')I (COol acre· do,'" ",- "',- mhO!! at IH". fool ratio 25"C) ( fIlll/l ) lIhull .f,

ij-I,hOO. RTO ~;HAIXlAT ClliDAD GU~RRnO,'l'A!'Ii\ULHAS--Contl""ed

Wut,,< Vdr 19F Mu.h .....,. Apr 1~41. m m 0 \?50 l>{I;' I.~~ 411iJ ,. '>9 1(,)0 1530 .., 1,960 MinI""..,. J,,"" , '" '"U 0 ~," (J '124 1,81 "U " " '" "' '" ." ." '" " " Wu.or Vea< 1~4B ,., Mu~I,.".,.f"b. 1~4H. 1,58 VI2 , 1/,90 m l.lJ 31bO 4.\0 12M 1160 ]950 U Minl_. 50Ft ••••••••••• ,., •••• '"',. '"'/.7 0 J,7 .>0 foJ " 4~~ ... " '" " " ." '" '" '" ~'... , Y"ar 1~4g Io\.ul",,,_, Mu<. 1949. n:. 11,0 ,~ VI? 0 1590 ...L~ )IIliJ ,." 1390 1260 '.0 10300 ... liihl..,,". AFr. .,J 0 1101 ". ,., 18? !II CO ~Q2 ,. " '" " '" ." " '" WM~r You 19~0

L~ ~. M~xi""",,,ItJ.r. 1950.. m 1M m l~bU 1.1 3810 18 1610 1500 ... 1,670 Mini ..,,",. J"t1e. D 1'.4 , In '" 48, .6(, m DO ,. " '"" " " ...." ... '" " \/u"r Yoar 1951 Maxi , IIIlr. 1951 179U >.> 1.4~ 3'190 5.16 1~60 1/,1,0 ... 1,620 ,. MI~I.. ,,,. ~"p~, '",.. "" '" "0 '" 1I11 ISS .0 ... '"'" " '" " " " ." " '" Wat~' V~8r 1952 Mud.",,", Fob. l~~".. m 0 H4 14'/0 1.00 ),1. 1020 ". ." ., Mint.."". Dct, 19SI. 0.' 0 .I() nl II'> '" .144 " " " '" " " ." " " lIalor Yur 19~1 M.l~l IIJ , o;l1 .13 m

•• o • &~L~ 00 zull- ~~ ~u 'i':" a .= ~~:i~~

]

0_ ,f o'

o ~. : 1•

I ~

LoU ~­ , U . :; § o. .!,• ,

,.

·,

,

·93 - T.•I>I. IQ--S..-TY of ch.teel .""Irue u .1_Ulle"."". elLwe uo, .,,~w_.In LI", ~In r..nn,l" b•• in

lUlulte 1" _1111 re_ I' IHe< u~" ... "'dl~al"dl DI ol..-OO .. 80ltdll ItArdlle.. Speclfl All CaCO, DO- con~ M,~ M",- Po- dium". Datil C>l- car~ Cu· Fluo NI- 0,· _. duel. Iron SodIum SulIat(l Chlorldo Nlll1- Cal- DJseblu'lre U" dum ...- bon· ride trate TonK ... (SIO,1 (f'e) "'- (Nal slum (Cl) W" ll;rn.H Tons dum. ~" pH eollllClloo (efa) (Ca) ,,= """. (00.) mlero~ (NO.,! (0' po< ear- P;:~~- " (MI:) (K) ", (P' po< Malt:~ (HCOJ (COol'" acre_ bon- nh(l!l al II tI'r '"d" ". .. ratio WC) hllli Jl '00' ilium ,

8_:lb39. ~10CRANllI': NF.A~CANI!TIU.O. TRX.

.,,, 4~1, Il<:t. l~. I~bl...... , .... VA ,.. l,ll lj'O ,., ~U4U .., .... I~' " '" " " " "., "" a_Hllg, \1I1,mIOR~~Ckl:SX NPo"H VAN IIORN, TRX.

,~ ""X, n. 1~66•••••• ... A.6 ,.. ~.I, 2.1, 0,1. I~l O.~(, U.'t ]11 .., "" " " " " "., '" " CilPI"1n CKr-Vol KI:/l8 (;/lNlf~t.\KI/I,T~X.

KlIr. )0. 1961.. wO.l1 , V ,." U. /\ , 1.') " " ".. '" "" '" "" "' " '" H_I/40. /l1"'''lITO l:Rr.r.l KI:A~PK"~lIllt),rr.x.

J.". I, 191>1...... "" ... U '00 '1.0 1.02 .., .., ,M 0'2 La, .. , '.2 ~~:1 /.1 , .~ , ,., H.... 0." ...., ...,.,., ... " " u ,.. m " " '" ". ,., ." Ju"~I...... '''' u , '.' I.') "., ."... , ... " " ... , ".., " ." ...... Ju". 21> ...... "n .." ,.. '" '"m " " ., ., ""m ". "... '"", , AUK 4 ...... " "u , ... ., ,., '" , ... 1.) Oo:l.12 .. , " ", .. ", .. ., " " '00" , '" " ... . '" " '" , ... J~M. " , 7). 19o, ...... -- " " '" 19b'" , " " "" "" '" ... H.or. " , 1lI1 , U 19" ...... m "'" " '" 8-J14~.n:JII.II«:U,\ CR£n NU~ TIl~I.IKr.IfA.TItJ. <0 ... Jeo. 1961 ~.6 , .. .., ,., 1010 1.46 '024 2'.6 1410 J...... '" , H.>r. J .• " ...... , .." ...... " " '"lib ,.. '"m , '" .., Ll l.S 1.48 4'14 ,'", ,." ..." J''''~I., ..• ,. " '" " 18) ,. , ".,'" '.0 ... "'"IIMI I." ." '"181 ,., 1'20 J ..o~ 27. .." ...... " '" ",., ", U '"'00 , ... '"., .., , ... U'" J.dy 20 .• HII " " ,., '.l 11.~ , ,'".. ',,4" ... , "" 1.1) IHO "" 190 IUO'" '/.4 OCt, 10 ." .. 1')1t 14)0 ,., ...... " '" ,.. , ". , I.' 1070'" '" Ibfo '"•. < .., .1.". n, 19M...... '" '" " '" '" 0 " 41lJ 14)0 ~rr,I , ,0> IHO '1.1 ...•...•..•.• .. '" .. ••" m '" 8-)1~0.RIO GAAND~~T JOHNSON KANClf NI:M CA5TOT.(ItI. TI!X.

~~" 'Ill. 1~61...... 0.01 IOl :y,U , y" IllO l. ~J 121 1610 " " '" ". '" "" '" '" " .. '1"lri hll .... U T.U. 10.-·5_ry of cb~.lul..... 1)'..... , .1o~~II.neO"1lien on Ilr.~••• " 1I1~RI.. Grand" h.. ln-_Cuml"u.d

\'~'~'" '" ~"""'~~. ,.., ,.,n U~~~, ... ,,,,,,,-.. ,.", Dillolvild IIOHd. llUMen Specltl DO_ li CaCO, M,,- V,_ "'- <00- Dale Mean Col- car· Cu- Fluo 111- D,- dlum SUic Sodium bo,- Bullate Chloride 1111111_ ducl- DlllchR.rge ~" clum ""- "',- bo,- ride URtC! T", Col;,1 "'- MOO ,II coilecUon (cll) (SIO.) (Fe) {Cal ,1= (Na) 811,lm 'I, (SO.) (Cl) Il,·n,." TonI " ate (PI (NO'> '"'(DI Ml\R'w car- ~~~.(mlcro- (Mg) (KI (CO.> """~l11,,_ (HeO,) ucro_ mhQ.ll at Illor"" "" day nc, bon_ ratio (mill)) fool "" ilium ate We)

K-I115. MIO CMJllmp,AT l,A~CTHY.UX.

JUll. II, 1~~2. IIAU 0.01 ,.. ,.. 0 o. , ~.~ O.H 1010 l.tI ,.. 1~80 " ", ". ". '" " ". " '" a-40e~. --- ~~Xl00 Of.l....IMU Rlvn NV...." Ul! M.urr. IIVW .., 19~1. ., M ,n , 19&0 ,., .10)0 2020 3440 0<". 1\, . ., ,,"•. 14, 1966 ',.9 DO , "00 '" •., .. 1'80 1140 ... " '" '" " " " "'" "" 8_lll~.SALT (SCkEWBI!AN) \lRAN N'J

,~, ,OJ , 5110 IIlor. 10, I), 20, n, 1941. 61\ 6120 J710 IUJon 11900 ,. ,- 31. . 1140 )940 , ,"00 $290 ""t. ", ~, ,,,'" 110'" " ,.., ~8600 Apr. 4, '. 14. 19. 21. 19.. '" ,,,, 20100 ""'" ~oo ,~oo ,. ""1 I. 9. 14. 19. 24. 29 .. ""1010 '"HO no'" ,• "'.j680 'h90 $020 " 28600 jun. ~, 9, 14 .. 1010 "00 , Jno ""00 .." 111(10 jul, 1, I, Il, I', 21, 1ft •• '" '" "'"'HO " "ul. 1, a. I), Ie. 23. 28. """ Sept. 1, e, ll. 18. 23. 1e 11800'""" Ikt. 3 . 21200 0<".e . 26900 Ikt, ll, 16900 ou. 18 .. 2&100 OCt. 21...... 2&100 OCt. n. H~oo <0 "ov. 2 ...•. H500 Nov. 10 .. NUOU 2))00 Nov. I'. 1<100 '" Nov. 20. IIIIOll Nov. 2~, Ilaoo Ofe. 20, .. '"''14(}1) 20100 I).~,2~. '"00 24700 Ofe. lO•.•.•. ~h~O J.". ~. 1~48. 1400 23500,"'" Ju. 10 .. >000 10100 J.n. l)" .... ,"00 J.n. 20 .. "''''23900 J.". n .. 11,00"'" 21100 Jan. )0 •• 1(.00 2JWO 'fD. ) ....•.• '400 '~oo hD. 10.••.•.• ·'4l!lJ ,~oo faD, 15 •• ,,'" 2)500 r.b. 20 .... '"00 21500 'Db. 15.•.• 21J{l .~, ;;:: ,. '"• .; Ci- " <;S<> .. ~~~ 88g88ggggg88~gg8 <,::8g .g:i- ... ~ ~§; ~~~~~ ...,x. ... E E" :5~~Ei3~i~~~a£=~~~ .!..c;£ " A~i ~~~ :: - --- ~---- o • g 00 ':'5-'~_ 5 > ·U Z {; . ~u , i':' ' 8 z= ~~~ ~.; ~ - ~~~ ~~~~~

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- 96- ;2gSl5l ;:.;~~:;;

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- 99- r~bl~to. --~u,_l(yuf "10"",10.( """Jy"". at """"JI,~",,,,,,,,"II.". "" Olr,,",", I" th" RI" (),,,,,,I,' h",d"--(;"",i<,,,,·d

,'••VI'. '" '"" "g'''''' I"" """ """"1'"".' ,,,,,,e"•.,·,,! Dtauolved &OlIds Hardn~BB Specl11 BI- asCaCO, so- Po- Cu- '00- Date Col_ M..- ear- Fluo NI- Bo- dium duct· M,~,1~ll',,- Sodium b,- 1","- Sul1ate Ch.lorlde Ml1l1_ Col- of (SI~)""00clum ride trate Tona Non- Rn<::e pH D!BchArge (Fe) ,1= (Nit) ilium "',"- ate (SO.) (Cl) 1;1""". Tuna clum, "'- collection (CII) ate (F' (NO,) '"(B' pO' car_ orp- (mlcro- ('f,' I" . (Mg) (H' (CO,) pO' ,.., Mag_ (lleO,) acrt!- t10n~l:;'hOSat Ii ter day ",- "",-ratio 25'Cj (,,"11 ) fool alum ,I,

B-I,I,~I,.OEVl.LS RIVr.R ~T P~fF(lRDr.Ro:;~nlr.~MR Cr.tlHOCX. Tl:X.

I,m. lU, 1~~1 D ...,., , ~.o 11.1 2:(h U.JI O.~ j

.hmr. I". l~~t. D 0.01, '.0 '.0 0./, , 0.' .., ,., 5.0 0.J6 0.2~ , n,2 J',O OCt. 20. 1958. "8.2 '"' 0 2 .8 ., '"' 0.28 "" , , m ,.," Feb. 19. 1962 ...... " .PI"' " "," '" ,." ... , ""R.n b ".1'11, . 'I~ "" , ,., ". .J) ,., , JRR .J'm. 17. 196.1 " " " ," ,. ". ., '-' ", '" '" '"' " " ." " " -- '" " " 8-101,%. lI~VLLSkl~P.~NP.H N~L RIO. n:x,

l(.n. 19. 19)0 D' , 1.n O.J. 100 ',: rlu ". lOll )~O , ., M,O A~".22. "''., "9.0 In , " ... , UO %, 1'1.<~~. " ,," , " '" ." , J~O J"ne. 1. " " J.I, " ".- '"2% .H " 0 ,., 18~ .1.~ Il~ , 'IW J"I~1, '" ", "" " 0 " "" " '" ". " Sept. 2. 6.ll , " la() ,. l5" no ,., 2\1, ". Oe'. J. " I, .0 '., '" ". .n IIlI Nov. 2~. .. ,., '"21,0 ," " ,1./0 m'" " " 4911 .. 0 m .,. 1/,6 0 L> 1.10 Feh. 16. 19JI. ", ." , W. " ". " " Jun" 18. 6.n '" , .., 191 ,/b , • no '" " " '"' ". '"' .., O.O~ IIU, 1'1.<,. ~. I ~l;' 1';4 U , ,., .- .H ,jl A .H,8 ,., Apr. n. U " "" , ", ... .m luI> 1',1, " .'. J511 ". 47?()". " ,. , 1./, .(l') Ih'l ...... , , M.y 30 .... " •• " , '" "", ,," " ,• , . June b .. 1180 " ".b '" , m 1',2 '00"' '"' ." lI,b , -l~4 July 24. I,ll ...'" M'" 0 ", II'" '"""I <50 '" ..." "'" " ." " " Aug. 26 .. 1,29 .. I~b 0 'J.b .JII ,.. , 8.2 Sept. 9. 201,00 H ",., 1:'1 , U ",, ." '"1/,8 lOR ., 1.0J'" ,. " _.'1 " •, ., :14'1 o"t. 2. ." " 7.1, " ... .m" 2:1) '" Dc.. ~. ,,, to m " '" II ... 2jJ .n ''" ., ,," " " " '" '" ", ,. ~bJ ,. • n,·c. ". 1~·1b. 4i~ m , ,., .. J. ..'", " " " '" " " '"' '" ~, " " ",,, ,., ./') ., I~"". ". m 1\" Apr. '"2/0 " '" ," " ,.. .e" I~" .n '"I',} "." ., m ,., ,~ M"y J) ~ 11.', , '1.1 .11 J. no .....•. ",,, " " '" " '"". J""o. 7M;' '" " " 1~1 .1" '"1J~ ".. ., JuLy. m " "e " I:> LO '"W. .1\ , '" 1,9 . ". " " "" " " ." '" • "" ,,. .71< , A"R. "', .Ii , ". ,n .'. m 1O,n , ,. '"113 0 U I 2',6 Sort. '" " " " " ", ." '" ". Tabl. 1O.•• SlJ.l""""'y M rh"ro«~l"""I.-eo", "I,cell.""",," "I,,,. ,," ""e""," I" ,h~Hl" Gra"dc l>•• 1"--C"t1l1,,,,~d

\Il<""\' '" .. II"Il,om. I'u' ""'r uX~~Pl,," """"",,,0) DIssolved solids HardneBB Specl11 BL- aB COlCO, "'- con- 0" t .. M,~ C",- M",- P,- car- Cu- Fluo Nl- dlum duct- ",- Sodium ~,- 000- Sullato Cl1Iorldll ",- IHlli~ C",- D1schJugs k" clum 000- rids tntl! ,"" TOllB Non- pH " r~~.i(Fe) (Na) Blum .~ (SO.) (CI) !l'rn.,,, Tons c!um, "'- colll!l::Uon (cts) (Ca) ,,= atn (P) (NO,.) (0) pO' ear- orp- (mlc:ro- (Mg) (K) (CO,.) pO' Mag_ "'" (IICOJ acre· 000- lion mbo:> at II t,·r "" M- ,~ ratio ("'r;!I) 1001 "" .1= 25'C)

8-4~Il.l.EWar 111U:; CH~I.KNEAK IJ~~KII). rH.

J,,,,. III, 19b7, J.-i ". 0 IHO ...II., IBIO l.I.G IHO 12~O O. , 2010 I'\;'T.1...... , ...... ,., '" " " 3.1 '" , 1410 " ., .. lllMI ~.~O 1:.00 14JO ., ~l"O "'.0 S~P<'7, ... m " "u u m'" 0 "78 " ., 8~n 1,17 , III~(J U B ,., '"n~ , U 121,0 ." HI,)". lIuv. •• 1'>" .. 0 "". " ." ., "00 II",. IJ. 19"S ...... " '" "'0 1.',00 "U " • " '" 8-4513. CANTU HRWC~ llII C11I~G!lSCJ(~~KIIIW\ U~l.R10, TEX.

J~n.Ii. 1961 ...... , O. , 7 .., 11\8 0.)9 ,. 11.1 .., 7.4 ". 1..1) ),1, I'\;>r. l. " " '1.7 ...."I.l '" 0 " ., U .H "'"2~" .. , , Z8.~ , 1,'11 ""-'r 'J " "" 7. J .., 1.1 11)'" " " "" 2"'. " July 6 .. "' U m " " ..• .., .W "H , l,e:1 U " ~"" " Sept. 1. " .., 27/, "." ., ,. I'IH " " " ". '"U " " '""m ... • ~u•. 8 .. ,. ~81 , " '" , 0." l% m " , '"~I', '" " "'" "" '" " " " ". " ~-"il~.'l.HAil FKl.Il"I: CRI:I~KA'r llOORf. r"'M~,11K!. RlCl, Tf.X. Jon. 10, 1961...... , n,? '.0 O. '14 n'l .. O. , "'. >., ~.9 . /,)1 H;,..7 .• ..... " '" 5.1, "., '"21,6 " 8.'"t ,. .0 9.1. '" .. n) ., 7.3 l1.y 2, " " ,." U ... "0 ...... ".'" .j.J " 4"8 ... , ~20 July 5. " " 6.'] " '"]Id '"Y.' 8.U .34 '" " 4

\K""""X ,. ""'Il~r",".,1"" ""'r "'<~I"". \"OH"""'I OIS110lved ll()lld8 Hardnellll SpeeUi D>- aa CaCa, "'_ COn- Date C~_ Malt- 1'0· C~- dlutll M"~ car- f'luo NI- Bo- C~_ duct. .1; Iron ",- SodIUlll 1.."18- 00,_ SuUal~Chloride lUll I. ol DJ.ecbaJ"g& SUtta clum 00'- ride trate Ton8 Non- >d- ance pll (Fe) ,lUlU (Ha) Ilium .~ ", "n,m.. Ton8 cluln, coJlecUon (Ca) atl' (SO.) (Cll (8) po< orp- (".) 1("°') (Mg) (K) (1-') I(NO.) po< Mi\g-- car- mIcro- (JlCO')1 (COs! acre_ "." bon- Uon m_ho, at lit .." 1001 d', ""- ratio 25'C) (,"~!1) 81Wl' ...

8-',~jQ."IN HLlI't: ~H~tKH~AHI)E~k1\', Tl:X.

2)1) , },If. ~ ~ )"n. 10, 19h1. U W /,'J , , ". , U 1).11 11 2h 1I, IIH. J. ~." " , , ,,' " , 1l~ , '"I,B "U 11I

8-1,530. PINTO '~l:EKM:A~~~L~lll. -- I'n.

_ I~bl 16~ .,, , 11,4 4114 J,n \, 1_" l61 114 11.'11 ". ll'/O ,., lI,r. H•• ~.II 1'\', " , " ,." " '"In ~~" '"." ", ,q', 4,4 '" ", 1]1,0 1,1, 1I"y 11. " J,'! "" " }l'n ., ,, '"Ill, ,'17 ~Ill '"ll" 1280 >.0 J/I, ,W ')2 , 11, I,~I July J'J. '" '" '" "' J." '"W ," '" ., U ' 512 ,."" /.' ". ~Hl 7~ ~"P" ~:' , 1 11'/ 1.'1 ''''''1111 n. " ""'00 '"' " " "'. ,." '" ,., '" "' ''" H<>". I~...... 6. 1, 1,0 .. 0 165 ., I,'l] ~<~ ~I)/,,, ~~O . <~(l J,m. 'I, 1'/08. '" 0 '" " 1180 ,"".. ". }10I I,IIH JIll, ~". ~ 1'1 '" '" 1150 '0 f-\.'y l~ ... , '" " 771 1,52 3-'1) 1260 ~ 8-4~80 K1U GAA~L>t;AT !:A(;~~~~SS.nx. 0 --- --_. - ~, , (I,~ (.7~ /WI. 1%,. (I,OJ .. 0 ,.. n O,9l ~~" i,'J 1010 ;,J '" F~b 1~. I~td_ H ,,. ;,\1 1.l0 jO, ,., j) 10 I " " "'" " '" ISl 0 '"'"' ""'" "" .'J" 0,''" .• (11ACllN CRt:l:1: NEAR l.ARI:Ull. l'l:X. - I-I"y 11, 19/,9_ " "" '" I(NIl '" " l~m 11M) lUI ',4,0 0.01 1,10 ~ 1<. " MJ(I " 8_1.~30,LilS OLMOS(:Rff.~~":~~un C~,\NI)~CITY. rl:X, lI"y 1I, 1%9. " " 66/0 " J~(,O W. 0 1010 ",00 11500 I~.6 ~080 1990 ". lBIOO " 1./\ 1,WA ~RFI:KA'r R~~I:RVillR~1T1'N~:,\~~1IM1·(lRIlYrl:.n:x. --- n~o ~1~1I Kay ~J, 1~1,9,.""", •• IH70 11 ~() I,HI 11)(1 41,8 9Y,G '" '" '" '" " " ""

" K".;d,,~"n ".,'pOTation nt I~O'C r.bl. Il.--Dhcl\l

,~<.u .... u •••••••• _ ...... , •. ".,,~. ~ .... u .. ~ •• u, DlII80I,ed lIOltM Hudnellll Sped! DO- li CaCO, 0>- M.~ M - Po_ eu_ dlum ,"'- CoJ- .. ou_ ~'IuoNI- Bo- duel_ CALENIMM Sodium b._ Sulfate Chloride 1111111_ CoJ- D1.!JchArp II~~~'"dum M' .... rIde Irate T",. Non- od- (SIO.) (Fe) (Na) ilium "',- .to (el) I:rll .... Tons cluln. ~" pH nAil (ef.) (eft) ,,= .to (SO.) (P) (NO,) '"(8) Clr- orp- (mlcro- (Mg) (H) ) (CO,) pO' PO< p" MlIl_ (IICD, acre- uon l~hOHal 111,er r",1 day ". "',-raUoo 25.C) (..It/O IIlullI .to

~-]M() klO I.Il\ANlJl A'f Xl. l'A~;O,'M(X.

19)). M' M. I.\} 1920 19J.1l.. 'H6 I.?~ 1160 ,~, 19]} ...... m'" .. m I.l~ 19]6 ...... " , ... l}]0 jJ~ J.8 ,~ "00 I.' 1931. .." " '" '"~Ol , '" '" ",, r.}1 '" '" ,. lll>O .., '" " '" '" '" ""' '" '" 19J~. , , 0,11 L~ ,. ,.. .. ,.. ". , Ibhll I7JO ., 1939 , ~ U~1l ...... " '" , no '" , ."". l. I 16010 '"' " .., 19'.0 .... '" .." "n '",n '" , '" .. ... l. 2~ l}~1l '"no '" ,", Jl9U .., " ,~, 1941 ...... '" '" , '" '" 0., ". I.JI JI'. '" ... 19~2. ."~/ll '''' " " '" '" , '" '" .. m,"'" H4 '" ·,., m "" " " " '" '" " ." " '" 19~1. .. on lJ1 n, .. .. 1.02 1/10 ~,I, n~ ,., 1~~4. ,• '"eld R' " '" '" !.tli Il'IU '")1!9 ". 11911 ,, 1945, . '186 " '",.. '"2J? , ,'"•. 1<2'" " ."'" I.U~ 1100 '"Illl " 1<10 .., 19~6 ... " " , nH .." ." ... 1.11 1~.l0 l~I,'"' ,.," J< \0 1941. .,. .." '" '" '"22] '''' .)!! !l1', 1.12 11.111 ''" 1.'1 IIMI ".. " '" • ". '" " '" '" . 1948 .•. >0, 160 , 28~ on ,., lUll 1.14 IIW U~ 4, , 1949 .• " " '" ~41 .. 1.0l "00 '"'0, ""1160 191oO ." ,• 2~~ ...... " " '" ''" '" " '"112 1.05 "" ·,.., 1110 " 19~1 ". .... '" " " '" '" '" ,•, " IH "el.,.. )~U '" ... \Jeo " 19~2. "' " " '"l)~ '" ,• '" '" ,, " "" 0.'" ,.. on ,, II ,0 ".. '" " " '''' '" '" " '" '"". I'~l.. '6) m , m , , ... l.Ot J. , 11111 19~~ ".. '"". , ". '" ,,.'" loltl '" '" '"HI! .. 1~10 ..", 19~5.. '. In lUlU 1. )~ ,,. I}I, , , 0 '" " '" '" " '" '" lHlJ 19M.. ".n, • ..'", IO~O l./d Il~ 1,.1 1)~O W " " '"". '" "• " '" " 19'1. .",. " " '" " '''' ".. H'i'" '" ,n ..," '" " "" '" '"' " '" "' ". "' '" "' " 19~8. .. , .. .~8 IO~O ... )(1/0 1939. '"HJ " '" no'" , '"' IHI " AJI'" 1.lj 1100 '" " Jl~O H,O" 19~O. , H~ 111 ." 1,11 J , nl " " '" '" ... "00 HIO "" '"I'd " UOll A.O '" H~ 1961. " " ... HI , III • ... 1.18 '11'1 '" I"l 11,11 , 1962 '"HO , ." lllO . 12'W ,., ...... •.. '" .."' " ", m '" • " '''' ''" ""'" ""'" " 19~J.. .. ,,,. I. 19 1690 III U20 ... 1964. ,• •~ ". , '" " " '" '" '"J'.O '" I .n" '" ," m IIU ·5,1. 11>.0 191>5•• " " " '" '" , '" ''''" 4JII Ill' '" 1961> ..... 6) 211". , ,,~ 'oJ ." 111• " '" " " " ,,, '" " ".. ". '" " ',"" " 1050'" " ." 1l~0 191>1...... '" .. " '" , .n '" I.lJ '" ... ,".. ".., ." ,~, 1968•...... '" " '" m '" '" " 1.?1 m '" , , .., " " ". " '" '" • ." ". '"

8·)610. ~10r.1tA~J)KA"r TOItlll1J.O nnlJCK ~K"""VAHKNS. TI~X.

l~l].. IHO !Jl0 !.IH ." ~,.e~~ ... "'~ .... .;

..;...; , ,

00 <:> c:O e cooo

- 104- g~;:;,;.;:::; "'~"'«>N ...... " "'''

· ~

, <;> ..ooe 0<:>000 i ~

.... ", .... "'><> ~-:;::;:::~

:...;

:;:;

- 105 - "'~"'-~Q ,...,.. ~"',.;..;

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I.,~ .,

co.ooc

,!

- 106- TAble II .··ll!.chAr~.·"olght.dAvenge of the ..!c.l conotitoen

R"""l". 1.11.. I t Ilgrl,." uc IlLor eXC"" A, ind!te,o") Dlallolved 80IIdli Hardncss SpecUl lil CaCO. po- 81- "'- 'M_ M,~ c,,- M.. - car- Cu- Fluo NI- dluln ,,",. ~,- 80- duct- CALENUAIl DJllCharl8 Slllca ",- Sodium Sulfate Chloride lU1U_ C"_ YEAR clum "".- rIde trate Ton/l NOn- ..- pH (dS) (SIO.) (Fe) (Ca) (Na) 81um "".- (SO.) (CI) '". ~I-a.." Tonll clum orp_ ~" ,'=(Mg) (K) ." (P) rNa,)(8) poe poe , car· mIcro. (HCO')I." (CO,) M;\I- 11 ter acre· ",- IMI ""'0, "".-raHo"'" F~~c}t ("R/I) ilium ."

6·1,',71.. P~COS~iV~RNIiAJl 5HUflU, TEX.

19~~ . 151 0 no 3. i 0,19 \440 t.96 1110 '.00 ,., 23~0 /I.U 19~b. '0' '"' '" " '"' 0 m .1> 1740 2. :\7 /q ", ,., 2770 ~, ", 19~7. 12~ 1.~8 ". '" H '" "0"" , m HI 1.2'" t IbO t690 2'1;1 ... 1~~0 .., "" "I,i, ." '" '"' 1958 .. HI '" , 2M 'I' >.l 1290 1.15 1)00 '"(,~I m 20)0 1959...... 1,05 '" .,. ,OJ , ,., 1.70 I:l/l() 1.\17 lSIO 47', l41 , , 2<20 '" '" '" ... " " ,~ '" '" ,~ . 1960 .• .. 'ol', , 398 ).1 .n 1950 2.65 1070 ,00 ,., lIOO 1.9 1961. '"m '" , ,...... J> t8l+0 l.'O 1170 "",.. ',~8 2960 I.~ 1962. ""'", m ., OJ' ,'".. ,OJ >.l .n 2120 2.ij~ ... "'/.7 H80 ... 1963. .," 1,1,6'" , ,w '" ", " '" 2050 2.19 "" 644 '"'>0" ,. J2l0 1~64. 439 , Id~ '" '" '" '.1 " lI50 1..\7 l:lbO"" ,.. 4.'1 lA60 '.0"" '" " '" '"' '" '" '. " 1965. , on , 1.~ .11 t4~O 2.03 fI.J 2/.00 1966 ,_. 06:1 , ~ ?~ ...... '" "" "" ". '""240 426'" 1. t210 1.67 '"on '"'I' '"I ,., 2010 ..'", ~ 1~6'1. ~ ,...... "" " ""31 '"'n , m u .10" \410 '.00 ,.. )1,8 b,) ,420 '/.9 ~ 1968. '" " n4 0 532 1.2 .1> 1i,90 2.03 I,n m ., 2'030 '" '" '" '" '" 8·',~90.RIO GMNPli ~" WEOO, 'rEX.

1956 JOM ,,. 0 III 0.80 1110 2&1. l.4 918 .,~". ~(In ," 1957. "~ ''I , 4H~U 1956. 6310 , 419 .".» 7140 21 , .. "" ". " ' .." "Ll '", 1959. 31.90 ,. 162 ., 6~~ " , " 1.980 ", Z,t ,., .I~ 1960 .•. nw Il , '"529 ." 4640 ". '" Z.I ." 1961 ...... 3290 152 , " 4~~ ... 4Jl0 nh ""IIlI '.0 no 0 1962. 1950 " 0 tOI" 3170 !.7 17~0 ." H6l . .." '" 107 '" .".OJ 302() ,,.'" '"118 U '" 1964. 4310 '"m ," ... 4190 ... 1965 21,1,0 , '" 2./, "" ...... "", '" " '" .Il 3630 m'" '''," 81.8'" 1966. JMo n , " 4~)'" .OJ i.850 n, ", 1,4 1967. 2460 '" , " ~. ,II, -- 2)1, " 1~68...... "' ,'".. , '" m 23/i '"1I1~ " ."'" "' " ." " 8-1,61). RIO CAANIlr. nr.t~·FALCON DAM, 1~X.

1~56...•.•...•.•. 1~10 I> , 0.1', "",1, 0.11, 3830 I~J Z., ,,. 19S1. " "' '" , '" " " .11 .51, 2~10 '"19:1 ... .,. " 19~6. "'"6930 '" "10 " '"DO , 'OJ" " U '" .53 1300 " I., U 1959 .. J~30 " " ". , no " u .1)'" '"4% .OJ I,no no'" ,OJ" ... """, 1960 .. 2~60 .. I'" "OJ 0 .. I> 551 .Il "no ~4J 1.1 " '"' " '" ." "." 1961 ..... ,"'. OJ .. '" , .. '>4', .'/1, 4490 :1)9 ,.. m ." H~ 2.~ 1962 .. 2930 " 00 '"no , '" " ." .,. 4421) 2)) '" on 1.9'" 1963. 2210 " " w, 210'"' " • .Il ;0' ... 3860 '" ,., tOLD 1964 .. '00' .," '" 111'" , '" .n .,. )020 In'" UO'" ,., ,." 1965 .. 3200 PO " 146 , II.'"' " 4)4'" H~O ,. .., ,. " '" ." ." ". " 1966. 2460 PO "", " 0 .. '" ... .., ... 3220 208 " ,., ,OJ ... 1967. 28S0 ., " '" 0 '" , .lI -- '" on 1968. .. " " .. ." 223 ,~ U 1,9 " '" ".'" " '"'.. .""' '" ." '" '" '" "" ~ Sa.. plu "<>Il~c,~d,,~arl..."guy, 3.~.,ilu d""".,,"",, af,", J"ly I. 1%1, T~hln11.··Ui..ln··C'>ntin",·,j

\1<•• ",,, In ''''''X<''_' ,", "." •. ~'«I" "" ,,"', ....·""1 D18801l'ed fIOHdll H-..rdnolB Spocl1\ DI- U CaCO, .,- M,~ M",- Cn- dlum '00- CoI_ '0- car- FI~ NI_ Bo- duct- CAU:NrIAR "I, 00- Sodium bo_ Sulfite Chloride .IlilU- D111chArU ~'"dum boo_ ride trat. ,., TonlL C.-Non_ ..- YEAR (SIO.) (Fe) olom (Nl) slum """- /tr".f1 TonI dum. Inc. pN (el.) (Cll) (SO.) (ell ~~p- (Y' (NO.1 (e, PO' Mag- car- mlcro- I"" (K' (IlCOJ'" (COol'" PO' acre- PO' UM II t(,c ..- """-ratkl m:~cit (al\/ll '001 "" .lum 0"

1I·~l>n.MIt) II....Nllt ~T K(1III\. nx.

194J. 171.(1 I Ii> BblO

~27n ~.ll 191.~ ~140 , , ., II. I ~ ,,. 1~4 . ... " .. ,"I '" ... HI L' '1)/ 1~1() ". .~~ 12~ .., 19115. " 115 , 111'".. '"1',1 .w i,5ln III IMi 1110 ,., ~ ." (,1')0 1~11 1946 ...... 4Wli " " ". , J' .'" III. 1..'1" 1.8 1~41. )~SO 1'l~ , l:iH 1111 .11, ~1.10 m 111 III 11',8 ,.. "'" " " " '" '" '" '" '" '""'. '" 1948. 4510 , ,., 41t1 SlbO 191< M ~.O 194~. ,., 14~ '9bO "," " "' '" , '" " .M'" '0. .. '" ,.. 1950 .. JOBO '" , I "'leI , .1> '010 l:i8 ,.. " ".'" I"'" .'" '" ." ''"',~, '" ." 19)1 ...... 2550 " " " ... , ... '" w U 111" II" 1952 .,," 1410 " " " , '" .." " '" " '" 1.2 ~H " '" " ". '" '" " """ '" '" 1953 .. 1610 I> ... , •. ... m ltllO M ,.. .I9~ ...... •. 2930 .." " , .." ,., ..." m .".•. )140 '"'Of "I,r, loll'" " " '" " " "'

8_41>41. RIO GItA~J)I:AT 'OIlT RlllOOOUl, KIO GkAIIlJK tlTY, T~X.

,,, 1,1\(>0 I.~ 1959. ))10 II ". W. , lid II 1.1 Il. 11 0.65 L' 1900 .. lOl,O .. , ".sw 1,590 '"1~1, '",>0 1,1, '" 1961. lHO 01" .. "' 1'J't"" , '"'... '" ", ."...... " I,~I 0 I~!I l. ~ "" "I .• \U~O .. 511, .,. 1,190 l?1I 8'.1, 1962 ...... "n .. , " '" '" ... ""' ,. 1~6J 1O~ lI.7'" , Wi "INO HI! l,U .• .... 7470 " " "'" .. " '''' ." '" I)' ,". ,." ~ 19M...... 2260 .. 14J , ., ... .. y,l!} 881, ,... , 1.1 .01 19&0 .., .. 0 1965...... 12&0 .. " " " '" "n '",... '" '""' " , 1966. lK90 " " . , '" .." '" "00 ,., "' ,.. 1961,",", ft,"O " '"1/.0 , U .. .,.'" ,.. .. '" "''' ..... _. " ••• " '" " " ." , '" " L' '" , 1'168. /0 .. , '" .n ... .. ,. , ,.. " " " '" '" '"" L' '" '"" '" 8·1.6~5.UO CUllll& AT RIO I:....IIDI CIrY. rn.

19)1., 41/>O I. 1)/. 8blO I'll:; ...... 9)20 '" . ill UOllO 1936. 1010 11'1 , ,.. '"55? ./0 ln~~l nil lH 1.4 8.J ,,. ," I!(~,(I ." 16~O ,., 10', 19]7 ...... '" " 129" , ,.. '" ." 1.\\ \11 LI llbO .., ,. II~OO II~ 1938 ..•....•.•.•.•. A4(,(1 " " \1,8 , '" '•. '1 ',I', .IP 11/. 1,/ L. " " '" " " ""' 1939 •. 101,00 II. .. , II> 11\1 ,., "', ... 10110 lllO 11.1 91,) ., ,... )~~O 1940 ...... H2O .. " lH'" , ,,, I. ~ ... ,.. IOl, '" .., 19"" " " I)' , ".'" " .f> 1.19 "000 1\K ,'".. ,,""'" ,.. 1942 .... ".".... "' " '"m , ,.,'" ..." L~ lO200 ,PI'" I'l" ,., ,,"" ,.. 1943 ...... 1880 , u l. I ~ IP. 1)10 ,.. .." " '" '" '" ".'" ... ."'" .." '" '" 19"" ...... "'. 16bO •. m , '00 ...... 11 ,- ~H ,W U ,.. 1945 •.••.• UIO " .." , ..'", ", 1.) .. bb~'" ,.., ,, 10'.0'" 1')1,( ~lllO ~.O ." 11/, " l.~ •.• " .. .." '" '"m , ')",0 '" ,." " ". '" ". " '" " '". '" Table Il.--Uu~harg"-..e1g1,~ed."euge

\KUUIt& \n ...\1118 ..... peT 11tH except ~" "''''~~'"''I

Dissolved soHds Hardness Speeltl So_ BI- as CaCO. eonw M,~ M - p.- Cu- CoJ- .. car- Fluo NI- B.- dluln ductw CALl=:NDAR UI, ,,- Sodium Iao- Sulfate Chloride YUl1w C"'_ D.Iecbarge "",- ride I"~ ,,, Tooe Non- ..- pH nAn (S10,) (Fe) ,,= (Na) elum "",- (SO.) (CI) Vo'"nll>; Tone clum, 00" (ela) "" (Cal ,1= .~ (F) (NO.) (B) pu carw .,,- (Mg) (K) (COol". pu Mag-- mlcro- (HCOJ acre· p'" boo- Hoo mhQ.!lat liler d., ",- ratlo 1001 .~ 25·C) (111:/ 1 ) Blum