Historical Overview and Limnological 

Reconnaissance of Theodore 

Roosevelt Lake, Arizona

By LISA K. HAM

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 95 4053

Prepared in cooperation with the 

ARIZONA DEPARTMENT OF 

ENVIRONMENTAL QUALITY

Tucson, Arizona 

1995
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY 

Gordon P. Eaton, Director

Any use of trade, product, or firm names in this publication is for 

descriptive purposes only and does not constitute endorsement 

by the U.S. Government.

For additional information Copies of this report can be 

write to: purchased from:

District Chief U.S. Geological Survey

U.S. Geological Survey Open-File Section

Water Resources Division Box 25286, MS 517

375 South Euclid Avenue Denver Federal Center

Tucson, AZ 85719-6644 Denver, CO 80225
CONTENTS

Page

Definition of terms........................................................................................................................................ VI

Abstract........................................................................................................................................................ 1

Introduction................................................................................................................................................... 2

Purpose and scope................................................................................................................................ 2

Acknowledgments................................................................................................................................ 2

Physical setting..................................................................................................................................... 5

Reservoir and stream characteristics.................................................................................................... 5

Approach and methods......................................................................................................................... 8

Lake measurements and sample collection.................................................................................. 8

Inflow and outflow measurements and sample collection........................................................... 8

Laboratory analyses..................................................................................................................... 9

Statistical methods....................................................................................................................... 9

Historical overview....................................................................................................................................... 9

Salt River Project data.......................................................................................................................... 9

U.S. Environmental Protection Agency studies................................................................................... 10

Arizona Department of Environmental Quality studies....................................................................... 14

Arizona State University study............................................................................................................. 15

Other studies......................................................................................................................................... 16

Results of limnological reconnaissance, 1990-92........................................................................................ 17

Physicochemical stratification.............................................................................................................. 17

Water chemistry................................................................................................................................... 22

Trophic status............................................................................................................................... 22

Major ions.................................................................................................................................... 24

Dissolved metals.......................................................................................................................... 24

Water-quality standards............................................................................................................... 29

Bottom-sediment metals.............................................................................................................. 31

Summary and conclusions............................................................................................................................ 31

Selected references........................................................................................................................................ 35

FIGURES

1-2. Maps showing:

1. Location of study area, Theodore Roosevelt Lake, Arizona.................................................... 3

2. Pinal Creek basin, Arizona....................................................................................................... 4

3-4. Graphs showing:

3. Elevation of Theodore Roosevelt Lake and discharge from 

Stewart Mountain Dam, Arizona, September 1990 

through May 1992 .............................................................................................................. 5

4. Stream discharges for Salt River, Tonto Creek, and Pinal Creek,

Arizona, September 1990 through May 1992..................................................................... 7

5. Map showing location of historical data-collection sites at

Theodore Roosevelt Lake, Arizona........................................................................................... 10

6. Pie diagrams showing major constituent distribution in water from

the Theodore Roosevelt Lake area, Arizona, 1980 through 1990............................................. 11

Contents III
CONTENTS

FIGURES Continued Page

7. Map and graph showing data-collection sites and temperature profiles

from the limnological reconnaissance at Theodore Roosevelt Lake, Arizona

A. Map showing location of U.S. Geological Survey

data-collection sites, 1990-92.................................................................................... 18

B. Graph showing temperature profiles for sites at the forebay,

Salt bay, and Tonto arm, May 1992........................................................................... 18

8-11. Graphs showing:

8. Temperature, specific conductance, and dissolved-oxygen 

values in the forebay, Theodore Roosevelt Lake, Arizona, 

September 1990 through May 1992.................................................................................... 19

9. Temperature, specific conductance, and dissolved-oxygen 

values in the Salt bay, Theodore Roosevelt Lake, Arizona, 

September 1990 through May 1992.................................................................................... 20

10. Temperature, specific conductance, and dissolved-oxygen

values in the Tonto arm, Theodore Roosevelt Lake, Arizona,

September 1990 through May 1992 ................................................................................... 21

11. Relation of Secchi-disc depth to specific conductance and 

dissolved-oxygen concentration in the Tonto arm, 

Theodore Roosevelt Lake, Arizona, December 1991......................................................... 23

12. Trilinear plots of compositions of water from Tonto Creek, 

Salt River, and Theodore Roosevelt Lake, Arizona, 

September 1990 through May 1992........................................................................................... 25

13. Diagram showing seasonal variations in the metalimnion in the 

Salt bay, Theodore Roosevelt Lake, Arizona, September 1990 

through May 1992...................................................................................................................... 26

TABLE

1. Morphometric features of Theodore Roosevelt Lake, Arizona............................................................ 6

2. Statistical summary of nutrient data for Theodore Roosevelt Lake,

Arizona, from the U.S. Environmental Protection Agency, 1975................................................... 12

3. Total-nutrient loading of Theodore Roosevelt Lake, Arizona, 1975................................................... 13

4. Sediment-metal concentrations at Theodore Roosevelt Lake,

Arizona, 1989.................................................................................................................................. 14

5. Statistical summary of nutrient data for Theodore Roosevelt Lake,

Arizona, from the limnological reconnaissance, 1990-92.............................................................. 23

6. Statistical summary of selected dissolved-metal concentrations in 

water samples from the limnological reconnaissance of Theodore 

Roosevelt Lake, Arizona, 1990-92................................................................................................. 27

7. Analyses from the limnological reconnaissance and Final Creek 

at Setka Ranch, Arizona, 1990-92, that exceeded or were outside 

the range of water-quality standards ............................................................................................... 30

8. Statistical summary of selected metal concentrations in bottomsediment samples from the limnological reconnaissance 

of Theodore Roosevelt Lake, Arizona, 1990-92............................................................................. 32

IV Contents
CONTENTS

CONVERSION FACTORS

Multiply

millimeter (mm)

centimeter (cm)

meter (m)

kilometer (km)

hectare (ha)

liter (L)

cubic hectometer (hm3)

cubic meter per second (m3/s)

gram(g)

microgram (ug)

kilogram (kg)

By

0.03937

0.3937

3.281

0.6214

2.471

0.2642

810.7

35.31

15,850

0.002205

2.205 x ID'9

2.205

To obtain

inch

inch

foot

mile

acre

gallon

acre foot

cubic foot per second

gallon per minute

pound avoirdupois

pound avoirdupois

pound avoirdupois

In this report, temperature is reported in degrees Celsius (°C), which can be converted to degrees Fahrenheit (°F) by 

the following equation:

°F = 1.8(°C) + 32

ABBREVIATED WATER-QUALITY UNITS

Chemical concentration and water temperature are given only in metric units. Chemical concentration in water is given 

in milligrams per liter (mg/L) or micrograms per liter (ng/L). Milligrams per liter is a unit expressing the solute mass 

per unit volume (liter) of water. One thousand micrograms per liter is equivalent to 1 milligram per liter. For 

concentrations less than 7,000 milligrams per liter, the numerical value is about the same as for concentrations in parts 

per million (ppm). Specific conductance is given in microsiemens per centimeter (u.S/cm) at 25°C. Chemical 

concentration in sediment samples is given in micrograms per gram (|ig/g). Micrograms per gram is equivalent to parts 

per million.

VERTICAL DATUM

Sea level: In this report, "sea level" refers to the National Geodetic Vertical Datum of 1929 A geodetic datum 

derived from a general adjustment of the first-order level nets of the United States and Canada, formerly called "Sea 

Level Datum of 1929."

Contents V
DEFINITION OF TERMS

Definition of terms is derived from Bates and Jackson (1980) and Chow (1964).

Chemocline The zone where salinity or specific conductance increases rapidly with depth.

Development of shoreline The ratio of shoreline length to the circumference of a circle whose area 

equals the surface area of the lake.

Development of volume (dv) A comparison of the volume of the lake with that of a cone; a circular lake 

would have a dv = 1, a dv > 1 represents a lake with basin walls that are concave toward the water.

Dissolved-oxygen minima A severe reduction in oxygen that can be caused by various processes.

Epilimnion The uppermost layer of water in a lake, characterized by an essentially uniform temperature 

that generally is warmer than elsewhere in the lake and by a relatively uniform mixing caused by 

wind and wave action.

Eutrophic lake A lake characterized by an abundance of dissolved plant nutrients and by a seasonal 

deficiency of oxygen in the hypolimnion; its deposits usually have considerable amounts of rapidly 

decaying organic mud and its water is frequently shallow.

Forebay The area of the reservoir that is immediately uplake from the dam face.

Hydraulic retention The storage time of a reservoir is determined by dividing the reservoir volume by 

mean flow of outlet.

Hypolimnion The lowermost layer of water in a lake, characterized by an essentially uniform 

temperature (except during a turnover) that generally is colder than elsewhere in the lake, and 

often is characterized by relatively stagnant or oxygen-poor water.

Limnology The scientific study of the physical, chemical, meteorological, biological, and ecological 

conditions and characteristics of lakes.

Maximum depth The greatest depth sounded in the lake.

Maximum length A line along the water's surface that represents the true open-water length of the lake, 

this line does not have to be straight and may cross islands.

Maximum width The straight-line distance between the most separated shores, which is approximately 

perpendicular to the maximum length.

Mean depth A calculated value of volume divided by area.

Mean width A calculated value of surface area divided by maximum length.

Mesotrophic lake A lake that is characterized by a moderate supply of nutrient matter, neither notably 

high nor low in its total production; it is intermediate between a eutrophic lake and an oligotrophic 

lake.

Metalimnion The horizontal layer of a thermally stratified lake in which the temperature decreases 

rapidly with depth. The metalimnion lies between the epilimnion and the hypolimnion and 

includes the thermocline.

Monomictic (lake) A lake with only one yearly turnover.

Morphometry The measurement of the form characteristics (area, depth, length, width, volume, and 

bottom gradients) of lakes and their basins.

Oligotrophic lake A lake that is characterized by a deficiency in plant nutrients and usually by abundant 

dissolved oxygen in the hypolimnion; its bottom deposits have relatively small amounts of organic 

matter and its water is often deep.

VI Contents
Pan evaporation coefficient Provides an estimate of annual evaporation losses from reservoirs.

Penstocks Dam structures that conduct water from the reservoir through the dam to the turbines in the 

powerplant.

Physicochemical Relating to properties that are both physical and chemical.

Senescence A lake that is approaching extinction as a result of sediment filling, erosion of the outlet, or 

other causes.

Slope of basin The slope of the basin is expressed as a percent of 45 degrees.

Shoreline length The length of the shoreline circumference.

Surface area The area enclosed within the zero-depth contour on a bathymetric map.

Turnover A period (usually in the fall or spring) of uniform vertical temperature when convective 

circulation occurs in a lake.

Volume Area enclosed by the depth contours plotted against depth, and the area under the curve so 

obtained may be planimetered or otherwise measured.

Contents VII
Historical Overview and Limnological 

Reconnaissance of Theodore 

Roosevelt Lake, Arizona

By Lisa K. Ham

Abstract

Theodore Roosevelt Lake (Roosevelt Lake) is a reservoir on the Salt River and Tonto Creek and a public 

water supply for the Phoenix, Arizona, metropolitan area. Roosevelt Lake potentially could be affected by 

contamination from the Final Creek basin and other upstream areas. Ground water in parts of the Final Creek 

basin contains elevated concentrations of manganese, copper, and other metals and contributes to the flow of 

Final Creek, which is a tributary of the Salt River. The purpose of this study was to determine the basic 

limnological processes within Roosevelt Lake using historical data and data collected by the U.S. Geological 

Survey during 1990-92.

Major-ion concentrations indicate that Roosevelt Lake is chemically influenced more by the Salt River than 

by Tonto Creek. Calcium and bicarbonate are predominant in water from Tonto Creek; sodium and chloride are 

predominant in water from the Salt River and Roosevelt Lake. A semilog-regression analysis of discharge from 

the Salt River resulted in a coefficient of determination (r2) of 0.79 for chloride and 0.73 for sodium. The greatest 

coefficient of determination for a constituent with discharge from Tonto Creek was bicarbonate (0.18). On the 

basis of stream inputs, discharge is not a good predictor of water chemistry leaving the dam.

Roosevelt Lake is a warm, monomictic reservoir. Data collected during this study indicate that Roosevelt 

Lake begins thermal stratification in February and becomes strongly stratified by April. Temperature and 

specific-conductance data indicate that thermal turnover was completed by December, although the 

dissolved-oxygen data were more indicative of a stratified condition.

Overall, Roosevelt Lake is considered to be mesotrophic. However, chlorophyll-a concentrations ranged 

from 0.70 to 14 micrograms per liter, and the mean concentration was 2.8 micrograms per liter, indicating 

oligotrophy. The Secchi-disc depth ranged from 1.1 to 3.0 meters, and the mean depth was 1.9 meters, indicating 

eutrophy.

Mean concentrations of dissolved arsenic, iron, manganese, nickel, and strontium were less in Roosevelt 

Lake than in the Salt River and Tonto Creek. The median concentration of dissolved manganese was 

0.45 micrograms per liter for the lake sites and 22 micrograms per liter for the stream sites. Concentrations of 

dissolved copper and zinc were greater in the lake than in the streams. The mean concentration of dissolved 

copper was 3.1 micrograms per liter for the lake sites and 1.6 micrograms per liter for the stream sites.

Of the lake sites, the forebay had the greatest mean concentrations of dissolved arsenic, iron, manganese, and 

zinc. The mean concentration of dissolved manganese for the forebay (114 micrograms per liter) was more than 

two times that for the Salt bay (46 micrograms per liter). This increase in concentration may be due to the greater 

thickness of the hypolimnion at the forebay, resulting in a larger reducing zone where metals desorb from 

sediments.

The mean concentrations of chromium, copper, and zinc in the bottom sediment were greater for stream sites 

than for lake sites. The mean concentrations of metals were greater for the bottom sediment from the Salt River 

than for those from Tonto Creek.

In the lake, mean concentrations of chromium, copper, nickel, and zinc in bottom sediment were greatest for 

sediment from the Tonto arm. Barium concentrations were greatest in bottom sediment from the Salt bay.

Abstract 1
INTRODUCTION

A system of reservoirs on the Salt and Verde 

Rivers provides most of the water used for 

irrigation in the Salt River Project (SRP) delivery 

area and for public water supply in the Phoenix, 

Arizona, metropolitan area. Two reservoirs on the 

Verde River and four on the Salt River provide a 

total storage capacity of about 2,490 hm3 (Boner 

and others, 1992). About 66 percent of the storage 

in the Salt River system is provided by Theodore 

Roosevelt Lake (Roosevelt Lake) (Boner and 

others, 1992). Roosevelt Lake is an impounded 

river that was created with the construction of 

Theodore Roosevelt Dam (Roosevelt Dam) from 

1904-11 and was the first in a series of reservoirs to 

be created on the Salt River for flood control 

(fig. 1). The reservoirs also are used for power 

generation, storage of irrigation water, and recently, 

have been used for recreational activities.

Ground water in parts of the Final Creek basin 

(fig. 2) contains elevated concentrations of 

dissolved solids and metals and contributes flow to 

Final Creek, a tributary of the Salt River. 

Dissolved-solids concentrations in Final Creek 

increased from about 2,700 mg/L in 1980 to about 

3,500 mg/L in 1989 (Eychaner, 1991). The 

concentrations of dissolved sulfate and manganese 

also increased during the same period. 

Concentrations of dissolved nickel began to 

increase in 1988, concentrations of dissolved iron 

began to increase in 1989, and alkalinity (buffering 

capacity) began to decrease in 1989. The plume of 

contaminated ground water was estimated to be 

moving downgradient at a rate of 0.2 to 0.3 km/yr 

(Eychaner, 1991).

The water quality of Roosevelt Lake potentially 

could be affected by contamination from the Final 

Creek basin and other areas. Current conditions in 

the lake need to be determined so that any changes 

in the water quality of Roosevelt Lake that might 

occur as a result of contamination can be assessed. 

A study of current conditions was done by the U.S. 

Geological Survey (USGS) in cooperation with the 

Arizona Department of Environmental Quality 

(ADEQ). The objectives of this study were to 

develop a data-collection program; estimate 

hydrologic, sediment, and chemical budgets for 

the lake from historical data; evaluate

the spatial and temporal distribution of 

physical and chemical conditions through a 

limnological survey of the lake; and evaluate, 

on a reconnaissance level, the extent and 

concentration of metals in the upper layers of 

bottom sediments. In this report, the term 

"metals" is used to denote metals and 

metalloids. This study fulfills part of the Clean 

Lakes Program Phase I Diagnostic and Feasibility 

study elements required by the U.S. Environmental 

Protection Agency (USEPA).

Purpose and Scope

This report reviews the physical and chemical 

limnology of Roosevelt Lake obtained from 

previous studies and presents baseline data 

collected during the USGS study. Water samples 

were collected by the USGS six times during the 

study (September 1990; April, August, and 

December 1991; and March and May 1992) and 

analyzed for major ions, total nutrients, and 

dissolved metals. The sampling included three lake 

sites (Salt bay, Tonto arm, and forebay), two inflow 

sites (Salt River and Tonto Creek), and the outflow 

from Roosevelt Dam. At each of the three lake sites, 

three water samples were collected at depths that 

were selected on the basis of thermal stratification 

except for the high-flow sampling done in March 

1992 when water samples were collected only from 

the metalimnion.

Bottom-sediment samples were collected and 

analyzed for metals four times during the study 

(April, August, and December 1991, and May 

1992). The sampling included the Salt bay, Tonto 

arm, and forebay; two sites on the Salt arm (at 

km 16 and km 9.5 from the dam); and the two 

inflow sites (Salt River and Tonto Creek). 

Bottom-sediment samples were collected from the 

lake sites in April 1991 using a BM-54 

bottom-sediment sampler and in August and 

December 1991 and May 1992 using a core 

bottom-sediment sampler.

Acknowledgments

Patricia Spindler and Thomas Trent of the 

ADEQ assisted with the collection of lake samples.

2 Historical Overview and Umnoiogicai Reconnaissance of Theodore Roosevelt Lake, Arizona
34-30

112-00' 111-15' 111-00' 110-45' 110=30'

34°151 -

34-00' -

33-451 

33-30

33°151 -

33-00'

Horseshoe ^ 

Reservoir i

Horseshoe

Dam

949S400-* 

0949S3SO\ 

<> .<^

 ^Pinal Creek 

basin 

boundary

Base from U.S. Geological Survey digital data 1:100,000,

Lambert Conformal Conic projection

Standard parallels 29°30' and 45°30', central meridan -91

1983

-96°00' 

0 5 10 15 20

I i

25 MILES

7

0 5 10 15 20 25 KILOMETERS

EXPLANATION

09500500A STREAMFLOW-GAGING 

STATION Number is 

site identifier

STUDY AREA 

(SHADED) AND 

WATER 

PROVINCES 

OF ARIZONA

Figure 1. Location of study area, Theodore Roosevelt Lake, Arizona.

PLATEAU UPLANDS 

PROVINCE

ARIZONA

Theodore

Introduction 3
111-00

33

HOMO1

33°30' 

EXPLANATION

0949S400A STREAMFLOW-GAGING 

STATION Number is 

site identifier

BOUNDARY 

OF BASIN

Midland 

'^Central

Base from U.S. Geological Survey, 1:24.000; Meddler Wash-Provisional. 1986; 

Dagger Peak-Provisional. 1986; Salt River Peak-Provisional, 1986; Rockinstraw 

Mtn.-Provisional, 1986; Chrome Butte, 1966; Inspiration, 1945; Globe. 1945; 

Cammerman Wash. 1966; Pinal Ranch. 1948; and Final Peak. 1964

Figure 2. Pinal Creek basin, Arizona.

Modified from Gellenbeck and Hunter. 1994

4 Historical Overview and Limnological Reconnaissance of Theodore Rooaevelt Lake, Arizona
The Arizona Department of Health Services 

(ADHS) provided analyses of 63 water samples and 

27 bottom-sediment samples. The Bureau of 

Reclamation (BOR) provided access to the outflow 

from Roosevelt Dam during the limnological 

reconnaissance.

Physical Setting

Roosevelt Lake is in the Central highlands 

water province (fig. 1). This province is a 

transitional zone between the Plateau uplands 

province to the northeast and the Basin and Range 

province to the southwest. The Central highlands 

province is characterized by isolated mountain 

ranges cut by steep-walled canyons and many 

ephemeral streams (Sellers and Hill, 1974).

Roosevelt Lake is in an area characterized by 

hot, dry summers and mild winters. Average air 

temperatures from June to September are above 

29°C (Sellers and Hill, 1974). Daily air 

temperatures range from 24° to 40°C during the 

warmest months of July and August; winter 

temperatures peak in the afternoon to about 15°C 

(Seller and Hill, 1974). In the Central highlands

province, 46 percent of the annual precipitation 

occurs from December to March (Sellers and Hill, 

1974) and approximately 30 percent occurs from 

July to September (Green and Sellers, 1964).

Reservoir and Stream Characteristics

Roosevelt Lake is a bilaterally shaped reservoir 

at the confluence of the Salt River and Tonto Creek. 

The lake receives water from the Salt River, Tonto 

Creek, and many small washes along its shores. The 

average inflow from the Salt River and Tonto Creek 

was 30 m3/s for 1942-91 (Boner and others, 1992).

During this study, Roosevelt Dam was being 

modified by construction, and the BOR was 

required to maintain a lake elevation of 

approximately 645 m (Dallas Regal, Salt River 

Project, oral commun., 1991). Because the actual 

discharge values from Roosevelt Dam were difficult 

to obtain, the lake levels were determined from 

releases from Stewart Mountain Dam (Dallas 

Regal, Salt River Project, oral commun(s)., 1992). 

Discharges from Roosevelt Dam generally are 

inversely correlated with lake elevation (fig. 3). The 

highest lake elevation during sampling was in April

655

Theodore Roosevelt 

Lake elevation

NOV | DEC | JAN FEB|MAR APR MAY |jUNE| JULY AUG |SEPT| OCT | NOV | DEC

Figure 3. Elevation of Theodore Roosevelt Lake and discharge from Stewart Mountain Dam, Arizona, September 

1990 through May 1992.

Introduction 5
Table 1. Morphometric features of Theodore Roosevelt 

Lake. Arizona

[m, meters; km, kilometers; ha. hectare; hm , cubic hectometers; yr, 

years; -, not calculated. See definition of terms]

Morphometric feature

U.S. EnvironRinne(1973) mental Protection 

Agency (1977)

1991; the lowest elevation was in September 1990. 

The maximum discharge from Stewart Mountain 

Dam during sampling occurred in March 1992, the 

next greatest occurred in May 1992. Mean storage 

for the study period was 1,106 hm3 (Salt River 

Project, unpublished data, 1992). The mean storage 

increased significantly from 716 hm3 in February 

1991 to 1,523 hm3 in April 1991. After this 

increase, the daily storage remained more than Maximum depth............. 62.5m 71.3 m

1,110 hm3 fortherestofthestudy. Mean depth..................... 24.3m 28.0m

Historical data from Roosevelt Lake differ Maximumbreadth .......... 3.87km ______

slightly for values of certain morphometric

features, depending on the source and date of the Mean breadth.................. 2.08km - 

data (table 1). According to Lara (1982), the Salt Length............................. 33.7 km ___ _ 

arm of the lake is 25.4 km long and averages 1.9 km wide and the Tonto arm is 17.5 km long and Shoreline length.............. 158.8 km ______

averages 1.4 km wide. The estimated total storage Surface area.................... 7,010 ha 6,070 ha

capacity is 1,704 hm3, the maximum depth is ,,, _nt , , _ .. 3 % J , ' __ . , -,«i« u Volume............................ 1,704 hm3 1,704 hm3

62.5 m, and the surface area is about 7,010 ha

(Rinne, 1973). A bathymetric survey of Roosevelt Development of

Lake done in 1909 indicated a surface area of volume........................ 1.17 

7,214 ha, total storage capacity of 1,877 hm3, and Development of

an elevation (at the top of the spillway gates) of shoreline..................... 5.34 _______

651 m (Lara, 1982). In 1981, the 1909 data were

, iii_, - Slope of basin................. 7.0 __________ used to recalculate the total storage capacity, ^

resulting in a value of 1,887 hm3 (Lara, 1982). A Mean hydraulic retenreplacement dam scheduled for completion in 1994 tion time...................... 694 days (1.9 yr)

will increase the storage capacity of the lake to

1,985 hm3, raise the lake level to a maximum depth

of 84.5 m, and increase the maximum surface area principal component. The mean specific

to 7,770 ha (Joel Sturm, Bureau of Reclamation, conductance was 3,412 |iS/cm, and the mean

oral commun., 1993). The average evaporation rate dissolved-solids concentration was 3,223 mg/L for

for 1963-73 was 249 cm/yr (Sellers and HiU, 1974). November 1990 to October 1991. The average

Pan coefficients provide an estimate of annual discharge for 1981-91 was 0.31 m3/s and the

evaporation losses from reservoirs based on the maximum discharge was 82.7 m3/s in July 1981;

measured evaporation from pans. According to base discharge in 1990 was 5.7 m3/s (Boner and

Green and Sellers (1964), the annual pan coefficient others, 1992).

for Roosevelt Lake for 1915-61 was 0.69. ^ ^ ^ -s ^ major ^^ rf

Pinal Creek originates in the Final Mountains, Roosevelt Lake. The total drainage area above

south of Globe, Arizona, and flows into the Salt streamflow-gaging station, Salt River near

River approximately 0.5 km upstream from the Salt Roosevelt (09498500), located 27 km upstream

River sampling site. The total drainage area for the from Roosevelt Dam on the Salt River, is

Pinal Creek basin above streamflow-gaging station, 1,115,300 ha (Boner and others, 1992). Upstream

Pinal Creek at Inspiration Dam near Globe from the station, the basin is sparsely populated;

(09498400), is 50,500 ha, of which about 8,500 ha land use includes livestock grazing, mining, and

is partly or entirely noncontributing owing to timber harvesting. The Salt River contains high

mining operations in the Globe area (Boner and concentrations of sodium and chloride ions and

others, 1992). The general water type for Pinal significant amounts of calcium and bicarbonate

Creek is calcium and sulfate with magnesium as a ions. A principal source of dissolved salts in the

6 Historical Overview and LJmnological Reconnaissance of Theodore Roosevelt Lake, Arizona
river has been traced to saline springs above 

Roosevelt Lake, providing the Salt River with its 

name (Arizona Department of Environmental 

Quality, 1992a). The mean specific conductance for 

1976-89 was 2,000 u.S/cm, and the mean 

dissolved-solids concentration was 1,120 mg/L. 

The average discharge for this site for 1913-91 was 

25 m3/s (Boner and others, 1992). The maximum 

discharge for 1913-91 was 3,314 m3/s in March 

1941; the minimum discharge was 1.7 m3/s in July 

1955 (Boner and others, 1992). Base discharge in 

1990 was 113 m3/s (Boner and others, 1992). 

During this study, the greatest inflow from the Salt 

River during sampling was in April 1991 and 

March 1992 (fig. 4).

Tonto Creek originates near the Mogollon Rim 

and flows southward into Roosevelt Lake. The total

drainage area for the Tonto Creek basin above the 

streamflow-gaging station, Tonto Creek above Gun 

Creek near Roosevelt (09499000), is 174,800 ha 

(Boner and others, 1992). The part of Tonto Creek 

basin above the gaging station is sparsely 

populated; land use includes livestock grazing, 

timber harvesting, mining, and recreation. 

Increased turbidity and concentrations of 

phosphorus and ammonia are thought to be the 

result of sand and gravel operations and range-land 

practices along Tonto Creek (Arizona Department 

of Environmental Quality, 1992a). The general 

water type for Tonto Creek is calcium and 

bicarbonate. Based on periodic measurements made 

between January 1976 and August 1991, the mean 

specific conductance was 419 u.S/cm and the mean 

dissolved-solids concentration was 234 mg/L. The

10,000 E

1,000 

o 

o

LJJ 

OT

tr

LJJ 

Q.

C/> tr

LJJ lLJJ

5

O

m

3 

o

LJJ 

CDtr

o

V)

o

100 SALT RIVER NEAR ROOSEVELT

TONTO CREEK ABOVE GUN 

CREEK NEAR ROOSEVELT 

09499000

0.01

0.001

-FINAL CREEK AT INSPIRATION 

DAM NEAR GLOBE 

09498400

SEPT OCT NOV DEC JAN FEE MAR APR MAY JUNE JULY AUG [)S|F SEPT OCT NOV DEC JAN FEE MAR APR MAY

1990 1991 1992

Figure 4. Stream discharges for Salt River, Tonto Creek, and Final Creek, Arizona, September 1990 through May 

1992. U.S. Geological Survey streamflow-gaging station number is in italics.

Introduction 7
average discharge was 4.3 m3/s and the median of 

yearly mean discharges was 2.6 m3/s for the 50-year 

period (water years) 1942-91 (Boner and others, 

1992). The maximum discharge was 1,739 m3/s in 

February 1980 (Boner and others, 1992). Tonto 

Creek had periods of no flow during 1940-91 

owing to infiltration of water into the alluvium. 

Base discharge in 1990 was 48 m3/s (Boner and 

others, 1992).

Approach and Methods

Lake Measurements and Sample Collection

During the limnological reconnaissance in 

1990-92, samples were collected from each layer of 

the lake and analyzed for total nutrients and 

dissolved metals. Layers were defined by physical 

and chemical field data, primarily temperature and 

dissolved-oxygen concentration. Prior to collection 

of water-chemistry samples, vertical profiles were 

made of temperature, pH, specific conductance, 

and dissolved-oxygen concentration. Secchi-disc 

readings were measured using a 25.4-centimeterdiameter, black and white disc. Lake-bottom 

sediments were analyzed for metal concentrations 

and the results compared with concentrations in the 

water.

Sets of samples were collected on the basis of 

lake stratification three during stratification 

(April and August 1991 and May 1992); one during 

turnover (December 1991); one during high inflow 

(March 1992); and one before turnover (September 

1990). Samples were collected for analysis from 

three sites in the lake one in the Salt bay (Salt 

bay), one on the Tonto Creek arm (Tonto arm), and 

one adjacent to the dam (forebay).

Depths sampled during stratification were used 

as a guide in sampling during turnover and 

transitional conditions in order to determine the 

effects of stratification on the water chemistry. 

Data from a multiparameter instrument, which 

measured temperature, pH, specific conductance, 

and dissolved-oxygen concentration, were used to 

determine the lake layers. Three locations were 

sampled within a vertical (one sample from each 

layer of the lake) the hypolimnion (bottom), the 

metalimnion (middle), and the epilimnion (top).

Two different sample-collection techniques 

were used for sampling the lake during the study. 

Prior to August 1991, water was collected using a 

peristaltic pump and teflon tubing hooked to a 

steel cable and lowered to the desired depth. To 

prevent contamination from the steel cable, a 

polyvinylchloride rod was attached to the anchor 

and the sampler intake was positioned about 1 m 

from the cable and anchor. From August 1991 

through May 1992, water samples were collected 

using a Van Dorn sampler instead of a pump. The 

Van Dorn sampler is triggered by a messenger 

weight and uses a plastic 6-liter bottle to collect the 

water sample at a specific point.

The procedures used for sample processing 

were consistent throughout the study. Water 

samples collected for determination of dissolved 

constituents were passed through 0.1-micron 

pore-size filters. Chemical preservation of these 

samples was done immediately after sample 

collection and all bottles were stored in coolers until 

analyzed.

Prior to August 1991, sediment samples were 

collected using a bottom-sediment sampler 

(BM-54) that was treated for the collection of 

sediment-metal samples. The BM-54 is a 

45-kilogram grab-sampling device that collects the 

top 5 cm of sediment. From August 1991 through 

May 1992, sediment samples were collected using 

a Wildco corer fitted with a plastic liner. The corer 

enabled the collection of sediment samples 5 cm in 

diameter and as much as 60 cm in depth. Regardless 

of the sample-collection device, the samples were 

placed in a teflon sieve and separated by particle 

size. Sediments less than 2 mm in diameter were 

sent to the ADHS laboratory for analysis of metals. 

Sediment samples were collected at each 

water-chemistry site and at two additional sites on 

the Salt arm.

Inflow and Outflow Measurements and Sample 

Collection

The inflows, Salt River and Tonto Creek, and 

outflow, Roosevelt Dam were sampled during the 

same week as the lake except for May 1992 when 

Tonto Creek was sampled a week later because of 

weather conditions. Additional samples from the 

Salt River site were used for quality assurance and

8 Historical Overview and Limnologies! Reconnaissance of Theodore Roosevelt Lake, Arizona
quality control. Duplicates of samples collected at 

this site for a national program were sent to the 

USGS national laboratory. The analyses of the 

original and duplicate samples were in agreement. 

The Salt River site and the Tonto Creek site were 

sampled using the equal-width-increment method 

(U.S. Department of the Interior, 1984). The water 

for the outflow sample was obtained from a hose on 

the outside of the powerhouse on the left bank 

below Roosevelt Dam.

Laboratory Analyses

The USGS National Water-Quality Laboratory 

analyzed water for dissolved inorganics, nutrients, 

chlorophyll a, chlorophyll b, and total and dissolved 

organic carbon. The ADHS analyzed water for total 

inorganics, dissolved solids, dissolved boron, and 

dissolved thallium, and analyzed bottom sediment 

for metals.

Although several statistically significant relations 

were found, this approach was not practical 

because the mean discharges were greater than 

the discharges in the data set. Finally, a 

semilog-regression analysis was applied using the 

logarithm of the discharge and the concentration.

HISTORICAL OVERVIEW

Major studies of Roosevelt Lake have been 

done by the SRP, USEPA, ADEQ, and Arizona 

State University (ASU) (fig. 5). Unless otherwise 

noted, interpretations of data from the SRP and 

USEPA were done by the USGS; interpretations of 

data from the ADEQ, ASU, and other studies were 

taken from published reports. Almost all historical 

data collected by State and local agencies were 

surface grab samples rather than samples collected 

from various depths in Roosevelt Lake.

Statistical Methods

Summary statistics for all constituents that 

contained censored data (values that were less than 

detection limits) were calculated using robust 

methods. These methods combine observed data 

above detection limits with below-limit values 

extrapolated, assuming a distributional shape 

(Helsel, 1990).

Linear- and logarithmic-regression analyses 

were done on the SRP data set to determine the 

level of confidence in conservative ions, which are 

used in calculations of metals loading. Because 

discharge measurements were not made during the 

SRP water-chemistry sampling, USGS daily mean 

discharges were used in the calculations. In setting 

parameters for the regression analyses, discharge 

was the independent variable and concentration was 

the dependent variable. The validity of the 

regression is measured using coefficient of 

determination (r2) values, which range from 0 to 1 

with 1 being optimal. Initially, linear regressions 

were done for the Salt River and Tonto Creek data 

using concentrations of dissolved solids, 

bicarbonate, chloride, and sodium; however, r2 

values were less than 0.57. Selected data points 

were then used to determine if a relation existed 

between low-flow discharges and concentrations.

Salt River Project Data

The SRP collected and analyzed grab samples 

from 1980 through 1990 for nutrients, major ions, 

and metals. The data set included water chemistry 

from Roosevelt Lake, the tailrace, the penstock, 

Salt River inlet, and Tonto Creek (Greg Elliot, 

Principal Environmental Scientist, Salt River 

Project, written commun., 1991). This section of the 

report presents the USGS interpretation of the SRP 

data.

Major-ion concentrations indicate that 

Roosevelt Lake is chemically influenced more by 

the Salt River than by Tonto Creek (fig. 6). Of the 

major ions analyzed, the sodium-plus-potassium 

concentration was 13 percent in Tonto Creek and 

35 percent in the Salt River compared with 

35 percent in Roosevelt Lake, 29 percent in the 

penstocks, and 31 percent in the tailrace. The 

greatest major-ion concentrations in Tonto Creek 

were calcium and carbonate; the greatest major-ion 

concentrations in the Salt River, Roosevelt Lake, 

the penstocks, and the tailrace were sodium and 

chloride. The lake water has been slightly 

influenced chemically by Tonto Creek, as indicated 

by the percentages of the bicarbonate concentration.

The semilog-regression analysis for discharges 

from the Salt River resulted in a moderate r2 value

Historical Overview S
33°50'

33°3ff

EXPLANATION

ARIZONA DEPARTMENT OF ENVIRONMENTAL QUALITY SEDIMENTSAMPLING SITE

U.S. ENVIRONMENTAL PROTECTION 

AGENCY WATER-QUALITYSAMPLING SITE

ARIZONA STATE UNIVERSITY PROFILE 

OF LAKE-SAMPLING SITES AND 

PROFILE DESIGNATION

Roosevelt 

Theodore Roosevelt Dam

10 KILOMETERS

110°50'

Base from U.S. Geological Survey digital data 1:100,000,1983

Lambert Conformal Conic projection

Standard parallels 29-30' and 45°30', central meridan -96°00'

Figure 5. Location of historical data-collection sites at Theodore Roosevelt Lake, Arizona.

of 0.79 for chloride and 0.73 for sodium. However, 

the predictive power is nil because the slope of 

the regression is not significantly different from 

zero. The greatest r2 value for discharges from 

Tonto Creek was for bicarbonate (rMXlS). A 

log-log-regression analysis was applied; however, 

no significant relations were found for either site. 

The regression analysis of discharge from the Salt 

River and Tonto Creek and the chloride 

concentration from the penstocks resulted in a small 

r2 value of 0.06, indicating that discharge of stream 

inputs is not a good predictor of water chemistry 

leaving the dam. Regression analysis was not 

consistent enough to warrant calculations of metal 

loads.

U.S. Environmental Protection Agency 

Studies

The USEPA has created guidelines for 

determining the trophic status of lakes. Trophic 

status is determined by nutrient and chlorophyll-a 

concentrations and by Secchi-disc depth, all of 

which indicate the level of productivity of the lake 

(criteria for classification are given in tables 2 and 

5). Eutrophic waters are nutrient rich, productive, 

and lead to lake senescence. Oligotrophic lakes 

are nutrient poor and mesotrophic lakes are 

intermediate in nutrient content.

The National Eutrophication Survey done in 

1975 by the USEPA (U.S. Environmental

10 Historical Overview and Limnological Reconnaissance of Theodore Roosevelt Lake, Arizona
Chloride 

(29.4 percent)

Theodore Roosevelt Lake

Calcium (11.1 percent)

Magnesium 

(5.3 percent)

Sulfate 

(5.8 percent)

Salt River intake 

above reservoir

Bicarbonate 

(142 percent)

/ Sodium + potassium 

(34.7 percent)

Chloride 

(34.2 percent)

Theodore Roosevelt penstock

Calcium (14.4 percent)

Chloride 

(27.6 percent)

Sulfate 

(6.3 percent)

Sulfate

Magnesium <6 -4 Percent>

(6.6 percent)

Bicarbonate 

(9.1 percent)

Calcium (10.1 percent)

Magnesium 

(5.3 percent)

Sodium + potassium 

(34.9 percent)

Tonto Creek at 

Chloride Punkln Center

(11.6 percent)

Sulfate 

(4.3 percent)

Bicarbonate 

(16.0 percent)

Sodium + potassium 

(29.1 percent)

Theodore Roosevelt tallrace

Calcium

Bicarbonate 

(34 1 percent)

Chloride 

(28.5 percent)

Sulfate 

(6.5 percent)

Magnesium 

(6.2 percent)

Calcium 

v (26 1 percent)

Magnesium 

(10.4 percent)

Sodium + potassium 

(13.4 percent)

/ Sodium + potassium 

(30.8 percent)

Bicarbonate 

(14.9 percent)

Figure 6. Major constituent distribution in water from the Theodore Roosevelt Lake area, Arizona, 1980 through 

1990. (Source: Data from the Salt River Project.)

Historical Overview 11
Protection Agency, 1977) was a nutrient study at 

Roosevelt Lake involving the collection and 

analyses of nine municipal waste-water samples, 

five lake samples from various depths, and seven 

tributary samples (referred to as 1975 data in this 

report). The results of the survey indicated that 

Roosevelt Lake could be classified as a mesotrophic 

lake. The USGS calculated summary statistics of 

Secchi-disc depths and concentrations of 

chlorophyll a and total phosphorous using the 

USEPA data (table 2). The mean total-phosphorus 

concentration and Secchi-disc depths indicated

eutrophy, and the mean chlorophyll-a concentration 

indicated oligotrophy. The report stated that 

primary nutrient limitation by nitrogen occurred 

during sampling; however, the report also stated 

that the algal assay test presented conflicting 

information. The algal assay test indicated that the 

addition of phosphorus alone stimulated algal 

production more than addition of nitrogen alone, 

but that the addition of phosphorus and nitrogen 

together produced algal yields an order of 

magnitude greater than yields from phosphorus 

alone.

Table 2. Statistical summary of nutrient data for Theodore Roosevelt Lake, Arizona, from the U.S. Environmental 

Protection Agency, 1975

[Data from U.S. Environmental Protection Agency (1977, p. 20)]

Site and diatance Number of .. .. 

upstream from tha dam aamplea

Salt arm, 10 km 

Salt bay, 5.5 km 

Tonto arm, 3 km 

Tonto arm, 9 km 

Forebay, 0.2 km

Salt arm, 10 km 

Salt bay, 5.5 km 

Tonto arm, 3 km 

Tonto arm, 9 km 

Forebay, 0.2 km

Mean Nation Minimum Maximum

:: (>3.7 m, oligotrophic; 2 0-3.7 m, mesotrophic; <2.0 m, eutrophie) 1

................ 2

2

3

................ 3 

2

 -

2.1 

1.5

1.4 

2.1 

1.9 

1.5 

2.1

0.21 

.02 

.35 

.38 

.07

1.2 

2.1 

1.5 

1.1 

2.0

1.6 

2.1 

2.1 

1.8 

2.1

--:--.;:;-.:., :-:::;. £&!3Z Chlorophyll-o concentrations, to micrograms per liter aL : 'I... ./^.^s..^^.-....!^ 1^^^^ 

iii (<7|lg/L, oligotropbic; 7-12 |ig/L, mesotrophic; >12 ng/L, eutrophie)2 . ' ': : -^^J^i^fiffjmtK:

................ 3

................ 3

3

................ 3

3

4.0 

4.0 

3.6 

4.0 

2.7

4.5 

4.9 

3.6 

3.9 

3.4

1.04 

1.65 

.35 

.12 

1.57

3.8 

3.9 

3.3 

3.8 

2.3

'Km^-: :s-'fm :w---:f:::^'S ,-;M:: Total pbosphorus as P, In milligrams per Uter. -. . . * ^fc.* ".' '>*Ji I 

^^ii^:^^::^ (<0.010 tag/L, oligotrophic; 0.010-0.020 mg/L, mesotrophic; >0.020 mg/L, eiitrophic)2 4:1 !

Salt arm, 10km 

Salt bay, 5.5 km 

Tonto arm, 3 km 

Tonto arm, 9 km 

Forebay, 0.2 km

. ...... 15

................ 16

. ............ 21

................ 15

................ 16

.02 

.02 

.02 

.02 

.02

.02 

.02 

.02 

.02 

.03

.01 

.01 

.01 

.00 

.02

.01 

.01 

.01 

.02 

.01

5.7 

6.8 

4.0 

4.0 

5.2

.05 

.03 

.07 

.04 

.10

U.S. Environmental Protection Agency (1974). 

2Arizona Game and Fish Department (1982-83).

12 Historical Overview and LJmnoiogicai Reconnaissance of Theodore Roosevelt Lake, Arizona
Nutrient loadings from point and nonpoint 

sources were determined in 1975 by the USEPA 

(table 3). Of the 126,490 kg/yr of phosphorus 

entering Roosevelt Lake, the net annual phosphorus 

accumulation was 82 percent. Of the 678,060 kg/yr 

of nitrogen entering the lake, the net annual 

nitrogen accumulation was 41 percent (U.S. 

Environmental Protection Agency, 1977). During 

1975, the point sources, such as municipalities, 

contributed approximately 12 percent of the 

total-phosphorus load and 6.9 percent of the 

total-nitrogen load entering the lake. Nonpoint 

sources contributed approximately 88 percent of the 

total-phosphorus load and 94 percent of the 

total-nitrogen load entering the lake. The study 

estimated the phosphorus loading to be 2.08 grams 

per square meter per year. Sources for nitrogen 

loads were not determined by the USEPA. 

According to Vollenweider (1975), Roosevelt Lake 

was classified as an eutrophic lake on the basis of 

annual total-phosphorus loading. Concentrations of 

naturally occurring phosphorus, however, are high 

in some soils and water in Arizona.

The National Dioxin Study was developed 

by the USEPA (U.S. Environmental Protection

Agency, 1986) to determine the extent of dioxin 

contamination nationwide. The most toxic isomer 

of dioxin is 2,3,7,8-tetrachlorodibenzo-p-dioxin 

(2,3,7,8-TCDD), a contaminant used in the 

manufacture of trichlorophenol, which is the 

most potent animal carcinogen identified by 

the USEPA. One of the areas investigated during 

the study was a group of helipad sites 

in the Final Creek drainage basin where 

the herbicides 2,4,5-trichlorophenoxyacetic acid; 

2,4-dichlorophenoxyacetic acid; and silvex were 

loaded on helicopters and then applied to more than 

1,000 ha of the surrounding area during 1965-66 

and 1968-69. Soil samples collected at five 

helipads, sediment samples obtained from nearby 

streams, tissue samples from several wildlife 

species (coyote, deer, frog, javelina, quail, snake, 

and toad), and a sunfish-tissue sample from a local 

stock tank were analyzed for 2,3,7,8-TCDD (U.S. 

Environmental Protection Agency, 1986). Dioxin 

was detected in soil samples from three of the 

helipads but was not detected in stream sediment or 

wildlife or fish tissues. One of the soil samples 

contained the greatest amount of 2,3,7,8-TCDD

Table 3. Total-nutrient loading of Theodore Roosevelt Lake, Arizona, 1975

[Data from U.S. Environmental Protection Agency (1977, p. 15-16)]

Inputs/Outputs

Phosphorus

Kilograms 

per year

Percent 

(approximate)

Nitrogen

Kilograms 

per year

Percent 

(approximate)

Inputs

Tributaries

Salt River..................

Minor tributaries...........

Municipalities...............

Direct precipitation .......

Total inputs.............

Outputs 

Salt River .....................

Net annual accumulation.

104,680

5,700

15,050

1,060

126,490

83

4.5

12

0.8

100

22,380 18

104,110 82

473,010

92,275

47,245

65,530

678,060

70

14

6.9

9.7

100

401,180

276,880

59

41

Hlatorical Overview 13
reported for any herbicide-use area sampled during 

the national study.

Arizona Department of Environmental 

Quality Studies

The ADEQ and the U.S. Fish and Wildlife 

Service (USFWS) collected one fish-tissue 

composite and three sediment samples from 

Roosevelt Lake as part of the statewide priority 

pollutants sampling program in 1989 (Arizona 

Department of Environmental Quality, 1991). This 

sampling program was part of a multi-agency effort 

to screen surface waters for 126 priority pollutants. 

Constituents detected in the fish-tissue sample 

included 4,4-dichloro diphenyl dichloroethylene 

(DDE), chromium, nickel, and zinc. Only DDE 

was present at concentrations greater than the

USEPA-recommended fish-tissue concentration. 

Constituents detected in the three sediment samples 

included antimony, arsenic, beryllium, chromium, 

copper, lead, nickel, and zinc (table 4). The 

antimony concentration (50.8 jig/g) in the sediment 

sample collected at Roosevelt Dam (forebay) 

exceeded the Ingestion Health-Based Guidance 

Level (IHBGL) recommended by the State 

of Arizona (47 mg/kg or 47 jig/g) (Arizona 

Department of Environmental Quality, 1992d). The 

beryllium concentration in sediments from all three 

sites exceeded the IHBGL (0.32 mg/kg). Pesticides 

were not detected in the three sediment samples. 

Concentrations of metals on the sediment generally 

were greatest for the forebay and least for the Salt 

bay. Copper concentrations were 87.5 jig/g for the 

Salt inflow, 84.5 jig/g for the forebay, and 39.5 jig/g 

for the Tonto arm.

Table 4. Sediment-metal concentrations at Theodore Roosevelt Lake, Arizona, 1989

[Data from Arizona Department of Environmental Quality (1991); J, indicates that the results are considered estimates and the data are valid for 

limited purposes, results are qualitatively acceptable; U, indicates that the constituent is not detected above the concentration listed; L, indicates 

results that fall between the instrument detection limit for waters or the method detection limit for soils and the contract required quantitation limit, 

results are considered estimates and usable for limited purposes]

Constituent Forebsy Sslt Inflow Tonto srm Laboratory blank

Concentrations, in micrograms per gram

Antimony......... .............

Arsenic .........................

Beryllium......... .............

Cadmium.......................

Chromium .....................

Copper...........................

Lead..............................

Mercury .........................

Nickel............................

Selenium. ...................... ,

Silver ............................

Thallium ........................

Zinc ...............................

............ 50.8

............ 16.3

............ 2.1

............ 3.3

............ 27.8

84.5

............ 22.3

............ .62

55.7

............ 1.7

............ 8.3

............ 1.7

............ 85.2

J

L,J

U

U

U

U

U

17.3 U

6.4

1.1 L

1.4 U

19.4

87.5

10.9

.30

35.7

.7 U

3.5 U

.7 U

53.6

21.5 U

14.2

1.2 L

1.7 U

23.2

39.5

17.9

.32 U

42.5

.9 U

4.3 U

.9 U

66.2

12.6

.4

.3

.8

.8

1.2

.4

.15

2.4

.4

2.0

.4

2.0

U

U

U

U

U

U

L,J

U

U

U

U

14 Historical Overview snd Umnological Reconnalsssnce of Theodore Roosevelt Lake, Arlzons
The ADEQ collected three water samples from 

Roosevelt Lake as part of the statewide Ambient 

Toxicity Testing program in April 1991 (Arizona 

Department of Environmental Quality, 19925). The 

goal of the program was to use aquatic organisms to 

determine the toxic effects of polluted waters. 

Samples from Roosevelt Lake were collected at 

depths of 1, 10, and 30 m and submitted for a 

48-hour acute toxicity test using the organism 

Daphnia magna. No mortality of Daphnia magna 

occurred in the three lake samples.

According to ADEQ Compliant Investigations, 

a complaint was filed against Inspiration 

Consolidated Copper Company for discharges into 

Miami Wash near Miami, Arizona, (fig. 2) after the 

18-inch-diameter main tailings line ruptured on 

October 30,1984. Flows reached Miami Wash in a 

slurry. Water-chemistry data were not collected.

In 1991, a complaint was filed about a 

rotten-egg smell at the mouth of Final Creek. 

Analysis of water samples from the beginning of 

perennial flow, from the mouth of Final Creek at the 

Salt River, and from two sites on Final Creek 

upstream from the mouth indicated gradients in pH 

and in metal concentrations. Water from the most 

upstream site had a pH of 5.9 and contained 

72 mg/L of manganese, 0.76 mg/L of nickel, and 

0.055 mg/L of copper. Water from downstream 

sites had near-neutral pH and lesser concentrations 

of metals. According to the ADEQ, the color of the 

water at the upstream site was black, apparently 

because of the concentration of manganese in the 

water. The greater manganese concentration was 

attributed to scouring of the channel upstream as a 

result of either increased flows in Final Creek or 

disturbance from reconstruction of an earthen dam 

upstream (Patricia Spindler, Aquatic Biologist, 

Arizona Department of Environmental Quality, 

written commun., 1993).

In 1993, a complaint was filed regarding 

unnaturally blue- or turquoise-colored water at the 

Bixby Road seep near the lower part of Miami 

Wash. The pH measured at Bixby Road seep was 

4.7, which is more acidic than the 6.5 water-quality 

standard for surface water (Arizona Department of 

Environmental Quality, 1992c). In the perennial 

reach of Final Creek, which is 2.4 km downstream, 

pH had increased 3 units, flow had increased 

fivefold, and conductivity was reduced by half. 

According to the ADEQ, the acidic Bixby Road

seep water was being diluted by less polluted 

ground water flowing into the Final Creek channel 

and as the water was oxidized, the pH was 

neutralized and copper was deposited on stream 

sediments. Efforts by the Final Creek Group, a 

mining company association, to contain the Bixby 

Road seep and other nearby seeps were recognized 

by the ADEQ and no enforcement actions were 

deemed necessary (Patricia Spindler, Aquatic 

Biologist, Arizona Department of Environmental 

Quality, written commun., 1993).

Arizona State University Study

In 1970-71, physical, chemical, and biological 

data for the Salt River reservoirs were collected by 

Rinne (1973), and the production and dispersion of 

fishes among the impoundments were determined. 

The purpose of this comprehensive study was to 

identify the significant abiotic and biotic factors that 

affect fish production and dispersion.

According to Rinne (1973), Roosevelt Lake is 

classified as a warm monomictic lake, being 

thermally stratified from April to November and 

mixed in late November to early December. The 

lake developed a thermocline at a depth of 4 to 6 m 

by June 1971. By August, the thermocline had 

reached a maximum depth of 15 m. Release of water 

through the generator penstocks located in the 

hypolimnion contributed to the lowering of the 

thermocline. Water temperatures reached 

maximums in August and September.

During the study by Rinne, pH, 

dissolved-oxygen concentrations, and specific 

conductance were measured. The pH ranged from 

6.7 to 9.4 in Roosevelt Lake. Dissolved oxygen was 

above 5 mg/L in the lake except within the 

hypolimnion during the summer. Dissolvedoxygen saturation near the lake surface was high in 

the spring (greater than 100 percent), was less in the 

summer (65 to 85 percent), and increased again in 

the fall (90 to 110 percent). The greatest depletion 

of dissolved oxygen occurred below the 

thermocline during August and September. 

Dissolved oxygen was uniformly distributed in 

the hypolimnion in December. The specificconductance values gradually increased from April 

to August and attained a maximum in July, then 

dropped slightly in the fall, and attained a minimum

Historical Overview 15
in April. The winter decline was attributed to 

decreased evaporation and water demands and 

increased discharge of the Salt River. Specific 

conductance ranged from 1,300 to 1,500 pS/cm.

Greater turbidity in the Salt and Tonto arms of 

the lake than in the central part of the lake was 

attributed to inflowing water and the stirring of 

nonstratified water by wind action in the more 

shallow parts of the arms. Turbidity in Roosevelt 

Lake ranged from 1 to 275 Jackson Turbidity Units 

(JTU) with a mean of 21 JTU. Roosevelt Lake 

serves as a settling basin for the Salt River 

reservoirs, intercepting and retaining silt from the 

Salt River and Tonto Creek and releasing silt during 

periods of high inflow. The ratio of the depth of the 

euphoric zone to Secchi-disc depth was 3.4 for all 

the Salt River reservoirs combined.

Phosphate values ranged from 0.01 to 2.8 mg/L, 

indicating eutrophy. Nitrate values ranged from 

0.01 to 0.70 mg/L, indicating oligotrophy. Vertical 

profiles indicated little variation in phosphate 

concentrations with depth in Roosevelt Lake 

even during summer stratification. Phosphate 

concentrations were greater for the Tonto arm than 

for the Salt arm of Roosevelt Lake. No significant 

spatial patterns of nitrate were apparent. Nitrate was 

greatest in August and November and phosphate 

was greatest in April, August, and November. 

Neither nitrate nor phosphate concentrations 

approach a level that would be considered limiting 

in Roosevelt Lake except on very rare occasions. 

Chlorophyll values were greater at the Salt arm and 

Tonto arm than at the forebay. Chlorophyll-a values 

ranged from 1 to 24 \ig/L, which were within the 

mesotrophic to eutrophic range. Secchi-disc depths 

were within the eutrophic range. These values may 

not be representative of normal conditions because 

the water level of the lake was low during the study.

The Salt River reservoirs contain about 

40 species of fish, mostly normative. Largemouth 

bass (Micropterus salmoides) was the top carnivore 

of Roosevelt Lake. Black crappie, (Pomoxis 

nigromaculatus), sunfish (genera Lepomis and 

Chaenobryttus), and catfish (Ictalurus punctatus) 

also are common in the Salt River reservoirs. 

Buffalofishes (Ictiobus sp.) and carp (Cyprinus 

carpio) are present in all four reservoirs and are 

locally abundant Threadfin shad (Dorosoma 

petenense) was the primary forage fish. Food 

resources consisted of the clam (Corbicula), two

species of crayfish, dipteran larvae, oligochaete 

worms, and a few aquatic insects other than 

dipterans. In terms of vertical distribution, most fish 

were found in the top 10 m of the water column 

during midday and 98 percent of all bass and shad 

collected were found above the thermocline.

Fish abundance was greatest in the Salt arm 

from August 1970 to April 1971 but was greater in 

the Tonto arm during August to November 1971. 

The central part of the lake west of Windy Hill (Salt 

bay) was the least productive. Schools of threadfin 

shad were found in greatest concentration over 

littoral areas and in coves. Greater food availability 

in the Salt arm and the influence of temperature, 

oxygen, and morphometry at the Salt bay site 

contributed to the greater fish abundance in the Salt 

arm. A strong correlation between chlorophyll-a 

and fish densities suggests that primary production 

was least variable relative to fish concentrations but 

the benthos concentrations varied inversely to fish 

concentrations. Predator-prey species interactions, 

lake morphology, chlorophyll-a concentrations, 

dissolved-oxygen concentrations, and water 

temperatures appeared to be the most important 

factors in determining the horizontal and vertical 

distribution of fish.

Other Studies

The Arizona Game and Fish Department 

(1982-83) conducted a water-sampling program at 

Roosevelt Lake from 1982 to 1983 at three sites. 

Physicochemical data were collected during July 

and December 1982 and March and May 1983. 

Thermal stratification was evident in July 1982. 

Dissolved-oxygen and temperature data indicated 

that Roosevelt Lake was not stratified in December 

1982, March 1983, or May 1983.

The USFWS (1991) conducted a biomonitoring 

study of bald eagle diet items in 1988. The objective 

of the study was to determine ambient contaminant 

concentrations in prey items and to assess 

contaminant exposure to resident breeding eagles. 

Two (whole body) composite fish samples from the 

Salt River upstream from Final Creek and four 

composite fish samples from the Salt arm of 

Roosevelt Lake were analyzed for organochlorines 

and metals as part of the study. Organochlorine data 

showed that only DDE was detected in

16 Historical Overview and Umnological Reconnaissance of Theodore Roosevelt Lake, Arizona
the fish-tissue samples from the Salt River 

compared with five organochlorines DDE, 

dieldrin, trans-nonachlor, and alpha and gamma 

chlordane detected in fish-tissue samples from 

Roosevelt Lake. The mean DDE concentration was 

greater in samples from Roosevelt Lake than in 

samples from the Salt River. Eleven metals were 

detected in the fish-tissue samples. On the basis of 

dry-weight analyses, concentrations of seven of the 

metals were greater in samples from Roosevelt 

Lake than in those from the Salt River.

The BOR collects weekly temperature data 

from seven thermocouples on the face of Roosevelt 

Dam and records the average daily elevations of 

Roosevelt Lake (Joel Sturm, Bureau of 

Reclamation, oral commun., 1992). A sediment 

survey was done in 1981 to calculate reservoir 

capacity and the volume of sediment that has 

accumulated since 1909 (Lara, 1982). The BOR 

resurveyed the area and calculated the surface area 

to be 7,016 ha and the total storage capacity to be 

1,648 hm3 (Lara, 1982). The loss of 239 hm3 in 

storage capacity from 1909 to 1981 was due to the 

accumulation of sediments and represents an 

average accumulation rate of 3.29 hm3/yr (Lara, 

1982).

RESULTS OF LIMNOLOGICAL 

RECONNAISSANCE, 1990-92

Physicochemical Stratification

Physical and chemical analyses were done at 

three sites in the lake Salt bay, Tonto arm, and 

forebay (fig. 7). During each sampling period, 

physicochemical data temperature, pH, dissolved 

oxygen, and specific conductance were collected 

at each of the three sites.

Roosevelt Lake is a warm, monomictic (turning 

over once per year) reservoir (Rinne, 1973). The 

temperature among the three lake sites during the 

study ranged from 10.5° to 30.5°C, with a mean 

temperature of 19.7°C. Results from this study 

indicate that Roosevelt Lake begins thermal 

stratification (developing three distinct layers, the 

epilimnion, the metalimnion, and the hypolimnion) 

in February and becomes strongly stratified by 

April. In May 1992, all three sites were thermally

stratified (fig. 7) and the metalimnion was at a depth 

of from 5 to 20 m. Stratified conditions remained 

through August, and by September the stratification 

was weakened. The lake appeared to be thermally 

mixed from October through December. The 

highest mean temperature (28.5°C) was in August 

1991 and was twice that of the lowest mean 

temperature (13.8°Q in April and December 1991. 

Within the water column, the mean temperature of 

the epilimnetic water was 22.8°C, the mean 

temperature of the metalimnetic water was 19.4°C, 

and the mean temperature of the hypolimnetic water 

was 16.9°C.

Areally, the Tonto arm appears to begin the 

process of turnover sooner than the Salt bay or the 

forebay (figs. 8-10). Consequently, the Tonto arm 

also begins thermal stratification before the other 

two areas of the lake. The reason for this difference 

is a combination of differences in depth and rate of 

inflow. The Tonto arm was the shallowest site 

sampled and was less affected by high-flow runoff 

than the Salt bay. The Salt bay and the forebay 

appear to begin thermal stratification at nearly the 

same time. The Salt bay is shallower than the 

forebay, but is more affected by runoff. The mean 

temperature (19.3°C) of the forebay was lower than 

that of the two other sites (19.9°C).

The pH for the three lake sites ranged from 

7.2 to 8.6 and had a mean value of 7.9. During the 

Rinne (1973) study, the pH ranged from 6.7 to 9.4. 

During the USGS study, the epilimnetic water had a 

greater mean pH value (8.3) than either the 

metalimnetic (7.9) or the hypolimnetic (7.6) water. 

Seasonally, the greatest meanpH value (8.1) was in 

August 1991; the least mean pH value (7.7) was in 

December 1991.

Specific-conductance ranged from 512 to 

1,950 uS/cm and had a mean value of 1,014 uS/cm 

for the three lake sites. During the Rinne (1973) 

study, mean specific-conductance values ranged 

from 1,300 to 1,500 uS/cm. During the USGS 

study, the mean specific-conductance value of 

the hypolimnetic water (1,085 uS/cm) was greater 

than that of the metalimnetic (1,010 uS/cm) 

or epilimnetic (949 uS/cm) water. Seasonally, 

the greatest mean specific-conductance value 

(l,908uS/cm) was in September 1990 and was 

almost three times greater than the least mean value 

(651 uS/cm) that occurred in May 1992. Areally, 

the mean value for the Tonto arm (1,058 uS/cm)

Results of LJmnologlcal Reconnslssance, 1990-92 17
110° SO1

5 10 15 20 

TEMPERATURE, IN DEGREES CELSIUS

Theodore 

Roosevelt 

Lake

Theodore Roosevelt

Base from U.S. Geological Survey digital data 1:100,000, 1983

Lambert Conformal Conic projection

Standard parallels 29°30' and 45°30'. central meridan -96°00'

EXPLANATION

09499000 T U.S. GEOLOGICAL SURVEY 

WATER-QUALITY AND 

SEDIMENT-SAMPLING SITE 

Number is site identifier

V" U.S. GEOLOGICAL SURVEY 

SEDIMENT-SAMPLING SITE

09500500V U.S. GEOLOGICAL SURVEY 

WATER-QUALITY-SAMPLING 

SITE Number is site 

identifier

Figure 7. Data-collection sites and temperature profiles from the limnological reconnaissance at Theodore Roosevelt 

Lake, Arizona. A, Location of U.S. Geological Survey data-collection sites, 1990-92. B, Temperature profiles for 

sites at the forebay, Salt bay, and Tonto arm, May 1992.

18 Historical Overview and Limnological Reconnaissance of Theodore Rooaevelt Lake, Arizona
0

5 

10 - 

15 

20 

25 

30 - 

35 - 

40 - 

45 - 

50

"

*

I lt....«;A-«*iv

(. '.'March 

r>* 1992 May 1992

September 1990

I 

j

«

/

/

f

I/

 December 

,1991

 | I

April/I / 

1991:'

i Si

W 

CC

LLJ

H 

UJ

UJ

o 

<

LL.

CC

£

LU

m

n: 

H

QL

UJ 

Q

0

5

10

15

20

25

30

35

40

45

50

10 15 20 25 30

TEMPERATURE, IN DEGREES CELSIUS

I I

- \

I December 

March .1991 

11992 ,

'* - x

MayN 

1992^

V

I \

\

C- April 1991

_|_ I

S

I I I

400 600 800 1,000 1,200 1,400 1,600 1,800 

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER

0

5

10

15

20

25

30

35

40

45

50

2,000

February 

1992

April 1991

2 4 6 8 10 

DISSOLVED-OXYGEN CONCENTRATION, IN MILLIGRAMS PER LITER

12

Figure 8. Temperature, specific conductance, and dissolved-oxygen values in the forebay, Theodore Roosevelt 

Lake, Arizona, September 1990 through May 1992.

Results of Limnological Reconnaissance, 1990-92 19
f '!' March 

<'--*f 1 "2 May 1992

September 1990

CO

IT

10 15 20 25 30

TEMPERATURE, IN DEGREES CELSIUS

5 -

r 10 -

15 -

LL

E£ 20 - 

25 -

LLJ 

O

CO

IT

£ 30 -

5 35

5 40 -

LLJ

m

£L 

LLJ 

Q

45 -

50

400

^ -> -.......

M*\ fe 'V

1992\ »1992

September 1990.

V".

I .

December

I S

\ \

I I I I I I

0

5 

10 - 

15 -j 

20 - 

25 - 

30 - 

35 - 

40 - 

45 - 

50 

600 800 1,000 1,200 1,400 1,600 1,800 

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER

2,000

February 

1992

May I

1992/

/

/ /* .../April ' ,*: 1991

-.. fS -*.'. 

December 1991

March 1992

I I

2 4 6 8 10 

DISSOLVED-OXYGEN CONCENTRATION, IN MILLIGRAMS PER LITER

12

Figure 9. Temperature, specific conductance, and dissolved-oxygen values in the Salt bay, Theodore Roosevelt 

Lake, Arizona, September 1990 through May 1992.

20 Historical Overview and Limnoiogical Reconnaissance of Theodore Roosevelt Lake, Arizona
0

5

10

15

20

25

30

35

40

45

50

/

' ' ' 

1 J«'*""'*° / 

-.^-*i _^*

*? '' i December May 1 992 _ -~~ 

../ i 1991 _ ' ' 

. 'March j -* ""^ 

~ :'f 1992 ! ^**"^

April /,' / 

1991/1 /

1 1 1 1

/September 

/ 1990

W

oc

Ul

10 15 20

TEMPERATURE, IN DEGREES CELSIUS

25 30

UJ \J

 z. 5

- 10

Ul

o

u.

OC 20

w 25

OC

Ul H ^fi 30

rf

| 35

5 40

O

-1 45

UJ

°° 50

ou

E 4C

- ' * " . December 1 "V"» 1991

v "#.... .

\ x """ ..

_ ^^ * * 

May* v 

1992X % March

\ \1992

 | »

1 i

I

»

1 1 1

)0 600 800 1,000

I I I J> I <"

FebT9a9r2S September] - 

199<J IK 1990 i

I ~~

J

'" .. April 1991 

"* ... t -

" ..

 . ~

 .

 .

_

I I I I

1,200 1,400 1,600 1,800 2,000

0

5

10

15

20

25

30

35

40

45

50

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER

., 1991

Mays'

.

I December * . 

11991 <t..''

N^.x/

.' . »March 

April » » 1992 

1991..-' ' /

2 4 6 8 10 

DISSOLVED-OXYGEN CONCENTRATION, IN MILLIGRAMS PER LITER

12

Figure 10. Temperature, specific conductance, and dissolved-oxygen values in the Tonto arm, Theodore Roosevelt 

Lake, Arizona, September 1990 through May 1992.

Results of Limnological Reconnaissance, 1990-92 21
was greater than the mean values for the Salt bay 

(994 nS/cm) and forebay (988 uS/cm). Although a 

change occurred in the specific conductance at the 

forebay in May 1992, this change did not occur at 

the other two sites in Roosevelt Lake. Therefore, no 

evidence existed of a developed chemocline during 

April 1991 or May 1992.

The dissolved-oxygen concentration ranged 

from 0.2 to 11.2 mg/L and had a mean of 6.2 mg/L 

for the three sites. Within the water column, the 

mean dissolved-oxygen concentration (3.6 mg/L) 

of the hypolimnetic water was less than that 

of either the metalimnetic (6.2 mg/L) or the 

epilimnetic (8.8 mg/L) water. Areally, the mean 

dissolved-oxygen concentration (5.8 mg/L) of the 

Salt bay was less than that of the other two sites 

(6.4 mg/L).

Ordinarily, when a lake or reservoir is mixed, 

dissolved oxygen will be replenished in the 

hypolimnion by atmospheric reaeration. 

Conversely, when the reservoir is strongly 

stratified, dissolved oxygen will decline because of 

consumption by respiration and decomposition 

processes. In December 1991, when Roosevelt 

Lake was thermally mixed, and in February 1992, a 

dissolved-oxygen minimum occurred in the 

metalimnion in conjunction with near anoxic 

conditions in the hypolimnion. In December 1991, 

the dissolved-oxygen concentration near the bottom 

of the lake was minimal except in the Tonto arm. 

Temperature and specific-conductance data 

indicated that thermal turnover was completed by 

December, but the dissolved-oxygen data were 

more indicative of a stratified condition. The mean 

dissolved-oxygen concentration for the lake was 

greatest in August 1991 (8.0 mg/L) and was least in 

September 1990 (4.0 mg/L).

Concentrations of manganese were elevated in 

the hypolimnion during turnover, probably as a 

result of the decrease in dissolved-oxygen 

concentrations. Manganese concentrations were 

elevated in the hypolimnion (820 ^g/L in 

September 1990 and 880 ^g/L in December 1991) 

when the concentration of dissolved oxygen 

approached zero. Dissolved-oxygen concentrations 

decreased to near zero in the hypolimnetic waters in 

September 1990 and December 1991 at the forebay 

and Salt bay sites. The December values were

anomalous because elevated dissolved-oxygen 

concentrations generally accompany equaltemperature conditions throughout the water 

column during turnover.

Transparency can affect the photosynthetic 

production of oxygen by its effect on the depth of 

penetration of photosynthetically active radiation. 

The changes in dissolved-oxygen concentration and 

specific conductance probably are light influenced 

(fig. 11).

Water Chemistry

Chemical analyses were done on samples from 

the three lake sites (Salt bay, Tonto arm, and 

forebay) and from the Salt River, Tonto Creek, and 

the outflow from the dam. The lake limnology is 

characterized in the following sections that discuss 

the trophic status of the lake and selected chemical 

and physical components of water from the lake and 

streams. Water samples from the three lake sites and 

three stream sites were analyzed for concentrations 

of nutrients, major ions, and dissolved metals.

Trophic Status

The trophic condition is commonly defined by 

concentrations of phosphorus, chlorophyll a, and 

Secchi-disc depth. Using data collected during this 

study, however, Roosevelt Lake could be classified 

as eutrophic (on the basis of mean Secchi-disc 

depths and mean total-phosphorus concentrations), 

oligotrophic (on the basis of mean chlorophyll-a 

concentrations) (table 5). Although these 

classifications differ overall, Roosevelt Lake is 

classified as mesotrophic.

Chlorophyll-a values provide a biological 

measurement of the primary productivity, as 

biomass, of the lake. During this study, 

chlorophyll-a concentrations ranged from 0.70 to 

14 \ig/L, and the mean concentration was 2.8 ^g/L. 

According to the classification scheme of 

the Arizona Game and Fish Department 

(1982-83), the mean concentration indicates 

oligotrophy. Chlorophyll-a concentrations during 

the 1975 study by the USEPA ranged from 2.3 to 

6.8 \ig/L, and the mean concentration was 4.1 ^g/L 

(U.S. Environmental Protection Agency, 1977).

22 Historical Overview and Limnologicai Reconnaissance of Theodore Roosevelt Lake, Arizona
855 858 861 864 867 

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER

870

Figure 11. Relation of Secchi-disc depth to specific conductance and dissolved-oxygen concentration in the Tonto 

arm, Theodore Roosevelt Lake, Arizona, December 1991.

Table 5. Statistical summary of nutrient data for Theodore Roosevelt Lake, Arizona, from the limnological 

reconnaissance. 1990-92

Location

. .,.,,-s:;:;-S:::-,,,,. .,,,..

:. .-.:.:.:-:".'"":".":: :"'"'"::'::|-|:f:|:!::.|::::.- :'|': ;:

Salt bay ..............

Tonto arm........... 

Forebay ..............

 :;r;:|||4:;:v-\, ::: |i;;|f

Salt bay ..............

Tonto ann ...........

Number Lessthan Median 

(percent)

.:::::::

6 

6

4

Kill (-

6 

6

5

Mean ?andard 

deviation

!!f:- si:- Secchi-disc depth, in meters '*ife. Milt-. 

(>3.7 m, oligotrophic; 2.0-3,7 m, mesotrophic; <2.0 in, eutrophic) 1 -M

0 1.7 

0 1.8 

0 2.2

1.7 0.3 

1.9 .7 

2.2 .5

: . , .: : Chlorophyll-a concentrations, in micrograms per liter w^ 

;7 ng/L, oligotrophic; 7-12 (ig/L, mesotrophic; >12 (ig/L, eutrophic)-

0 2.1 

0 1.5 

0 1.5

3.8 5.1 

2.4 2.1 

2.2 1.3

Minimum

1.2 

1.1 

1.7

.80 

.70 

1.3

Maximum

: W;:|r'.;;||;||::v;;i

2.0 

3.0 

2.7

???-. S:S;::?::v-ft;

14 

6.5 

4.3

*jjm::^;m&m? "Rrtal phosphorus as P, in milligrams per gram :.:Mi ,.,.*- $* :.-,-->:. ..s?-; 

; .'iVl^sjg-.i"! ' 4dM)io mg/L, oligotrophic; 0.010-0.020 mg/L, mesotrophic; >0.020 mg/L, eutrophfc)2 ;:: ^.^Kl^

Salt bay .............. 

Tonto arm ...........

16 

17 

15

25 .02 

24 .02 

33 .03

.03 .02 

.02 .01 

.04 .03

.01 

.01 

.01

.10 

.05 

.13

1UJ5. Environmental Protection Agency (1974). 

2Arizona Game and Fish Department (1982-83).

Results of Umnoiogical Reconnaissance, 1990-92 23
Because different laboratory techniques were used 

for determining chlorophyll-a concentrations, the 

1975 data cannot be compared with data from this 

study (Paul Soliven, U.S. Geological Survey, 

1994). For this study, the greatest mean value 

(4.3 ng/L) was in December 1991; the least mean 

value (0.9 ng/L) was in August 1991. Areally, the 

Salt bay had the greatest mean value (3.8 |J.g/L), the 

Tonto arm had a mean value of 2.4 ng/L, and the 

forebay had the least mean value (2.2 (ig/L). 

Chlorophyll-a concentrations were consistently 

greater adjacent to inflows than in the center of the 

lake during the Rinne (1973) study and during this 

study.

The Secchi-disc depth ranged from 1.1 to 

3.0 m, and the mean depth was 1.9 m. This depth 

lies within the range of values indicating eutrophy 

(U.S. Environmental Protection Agency, 1974). 

Areally, the greatest mean Secchi-disc depth was 

2.2 m at the forebay, an area less affected by runoff 

than the other two sites on the arms of the lake. The 

least mean depth was 1.7 m on the Salt bay, an area 

affected by runoff. The greatest mean Secchi-disc 

depth (2.6 m) occurred during stratified conditions 

in August 1991; the least mean depth (1.1 m) 

occurred in April 1991 after large inflows from 

March storms.

Phosphorus availability generally is thought to 

be the critical factor in eutrophication of lakes. For 

this study, concentrations of total phosphorus for 

Roosevelt Lake were within the range considered 

eutrophic (Arizona Game and Fish Department, 

1982-83). Concentrations of total phosphorus 

ranged from 0.01 to 0.13 mg/L, and the mean 

concentration was 0.03 mg/L. Areally, the greatest 

mean concentration of total phosphorus 

(0.04 mg/L) was at the forebay; the least mean 

concentration (0.02 mg/L) was on the Tonto arm. 

Seasonally, little difference occurred in the mean 

concentrations (0.02 to 0.04 mg/L). The mean 

concentrations of total phosphorus were similar in 

1975 and 1992 and both data sets indicated that the 

forebay had a greater concentration of phosphorus 

than the arms of the lake. Within the water column, 

the greatest mean concentration of total phosphorus 

(0.05 mg/L) was in the hypolimnion; the least mean 

value (0.02 mg/L) was in the epilimnion.

Major Ions

Chemically, the water sampled from the lake 

sites was more similar to the water from the Salt 

River rather than to the water from Tonto Creek 

(fig. 12). Tonto Creek differed chemically from 

the Salt River, Roosevelt Lake, and Roosevelt 

Dam outflow. Calcium and bicarbonate were 

predominant in water from Tonto Creek and sodium 

and chloride were predominant in water from the 

Salt River and Roosevelt Lake. This chemical 

difference also was indicated by the SRP data.

Concentrations of major ions were greatest in 

September 1990 and were least in April 1991 and 

March and May 1992. The sampling in September 

1990 was preceded by several weeks without 

precipitation and the April 1991 and March and 

May 1992 sampling was preceded by several weeks 

during which precipitation may have produced 

sufficient runoff to cause dilution. Seasonal 

variations were evident in the chemical data from 

all of the lake sites but were most pronounced in 

data from the metalimnetic water of the Salt bay 

(fig. 13).

Dissolved Metals

Summary statistics for arsenic, barium, copper, 

iron, manganese, nickel, strontium, and zinc 

were determined using estimates from robust 

log-probability regressions (Helsel and Conn, 1988; 

table 6, this report). Concentrations of cadmium, 

lead, and selenium were less than their respective 

analytical detection limits.

Concentrations of dissolved arsenic, iron, 

manganese, nickel, and strontium were less in lake 

water than in streams (table 6). The median 

concentration of dissolved manganese at the lake 

sites (0.46 ug/L) was considerably less than the 

median concentration in the streams (22 ng/L). The 

mean concentration of dissolved barium was the 

same at the lake and streams sites (61 ng/L). 

Concentrations of dissolved copper and zinc were 

greater in the lake than in the streams.

The mean and median values for each 

constituent varied significantly, primarily due to the 

number of censored data and the varied detection 

limits. The median concentration of dissolved 

manganese at the lake sites (0.46 \ig/L) was less

24 Historical Overview snd Limnological Reconnsisssnce of Theodore Rooseveit Lake, Arizona
STREAM SITES

CALCIUM IALCIUM CHLORIDE 

PERCENT IN MILLIEQUIVALENTS PER LITER ^ ^

LAKE SITES

CALCIUM CHLORIDE

PERCENT IN MILLIEQUIVALENTS PER LITER

Figure 12. Compositions of water from Tonto Creek, Salt River, and Theodore Roosevelt Lake, Arizona, September 

1990 through May 1992.

Results of Llmnologlcal Reconnaissance, 1990-92 25
SODIUM + POTASSIUM

MAGNESIUM 

CALCIUM

SULFATE

,;|| BICARBONATE + CARBONATE 

CHLORIDE

May 1992 at a depth 

of 12 meters

March 1992 at a depth 

of 10 meters

December 1991 at a 

depth of 12 meters

August 1991 at a 

depth of 8 meters

April 1991 at a depth 

10 meters

September 1990 at a 

depth of 7 meters

16 12 8 4

CATIONS, IN MILLIGRAM 

EQUIVALENTS PER LITER

4 8 12

ANIONS, IN MILLIGRAM 

EQUIVALENTS PER LITER

16

Figure 13. Seasonal variations in the metalimnion in the Salt bay, Theodore Roosevelt Lake, Arizona, 

September 1990 through May 1992.

26 Historical Overview snd LImnological Reconnaissance of Theodore Roosevelt Lake, Arizona
Table 6. Statistical summary of selected dissolved-metal concentrations in water samples from the limnological 

reconnaissance of Theodore Roosevelt Lake, Arizona, 1990-92

Qig/L, micrograms per liter, , dashes indicate value not determined; ND, not detected]

Site

Salt bay 

Median.......................................... .. ......

Standard deviation........... .....................

Number of samples ..............................

Percent of samples with concentration

Tonto arm

Median.. ................................................

Number of samples ..............................

Percent of samples with concentration

Forebay

Median....... ................................ ...........

Mean.. ............................................. ......

Standard deviation... .............................

Number of samples ..............................

Percent of samples with concentration

All lake sites

Median....... ........................................ ...

Standard deviation... .............................

Number of samples ..............................

Percent of samples with concentration 

below detection limit.. .....................

Arsenic

2.0

2.3

.7

16

31

3.0

2.7

.4

17

41

2.2

2.8

1.2

15

33

2.4

2.6

.87

48

35

Barium

(WI/L)

46

57

26

16

0

53

63

25

17

0

53

62

26

14

0

52

61

25

47

0

Copper

2.1

4.0

4.8

16

62

.59

2.6

4.6

17

76

1.2

2.1

3.4

15

73

1.5

3.1

4.3

48

71

Iron

4.0

8.3

16

16

38

3.0

42

5.3

17

53

5.0

20

42

14

43

4.0

11

25

47

45

Manganese

(WI/L)

0.3

46

129

16

75

17

88

.21

114

000

15

73

.46

54

185

48

79

Nickel

(WJ/L)

0.68

1.7

3.3

16

62

17

82

15

80

.30

1.3

27

48

75

Strontium

(WJ/L)

300

330

91

16

12

293

306

42

17

42

290

317

00

15

13

295

318

78

48

17

Zlno

(WJ/L)

3.0

3.4

2.6

16

50

1.6

2.9

3.2

17

71

3.5

3.9

23

14

50

3.0

3.6

27

47

57

Results of Limnological Reconnaissance, 1990-92 27
Table 6. Statistical summary of selected dissolved-metal concentrations in water samples from the limnological 

reconnaissance of Theodore Roosevelt Lake, Arizona, 1990-92 Continued

Site

Salt River

Standard deviation...... ..........................

Percent of samples with concentration

Tonto Creek

Median.. .......................................... ......

Standard deviation... .............................

Number of samples ..............................

Percent of samples with concentration 

below detection limit............. ..........

Roosevelt Dam outflow

Mean....................... ........................... ...

Standard deviation... .............................

Percent of samples with concentration 

below detection limit.. .....................

All stream sites 

Median.. ............................................. ...

Mean.. ............................................. ......

Standard deviation...... ..........................

Percent of samples with concentration 

below detection limit.. .....................

Arsenic

4.0

4.2

29

5

0

2.0

2.2

1.1

5

40

3.3

1.5

5

40

3.0

34

2.0

15

27

Barium Copper iron

25 1.0 18

38 1.4 17

35 .5 1.8

555

40 0 40

68

70

96

555

20 60 80

61 - - 9.0

61 54

in OR

555

20 60 20

56 1.5 7.0

61 1.6 23

28 .72 58

15 15 15

27 40 47

Manganese

(WJ/L)

370

376

244

5

0

7.1

8.8

7.5

5

40

12

320

429

5

20

22

236

311

15

20

Nickel

(Mfl/L)

2.0

2.2

1.1

5

20

ND

ND

ND

5

inn

2.0

3.2

3.8

5

20

1.1

2.0

24

15

47

Strontium

637

564

295

4

25

190

194

43

5

20

330

362

62

5

20

314

356

213

14

21

Zinc

(HS/L)

ND

ND

ND

5

inn

5

80

3.3

3.3

.67

5

40

2.6

2.9

1.0

15

73

28 Historical Overview and Umnoiogical Reconnaissance of Theodore Roosevelt Lake, Arizona
than the mean value (54 |ig/L). The median 

concentration of manganese at the stream sites 

(22|ig/L) also was less than the mean value 

(236 Mg/L).

The mean and median concentrations of 

dissolved arsenic, manganese, and strontium were 

greater for the Salt River than for Tonto Creek. The 

mean concentration of dissolved strontium for the 

Salt River (564 [ig/L) was almost three times 

greater than that for Tonto Creek (194 ^g/L). The 

median concentration of dissolved iron for the Salt 

River (18 |ig/L) was greater than the median for the 

Roosevelt Dam outflow (9.0 ^g/L); however, the 

mean concentration for the outflow (54 ng/L) was 

greater than the mean for the Salt River (17 ^g/L). 

The median concentrations of dissolved nickel were 

the same for the Salt River and the dam outflow 

' (2.0 Mg/L).

Of the lake sites, the forebay had the greatest 

mean concentrations of dissolved arsenic, iron, 

manganese, and zinc. The mean concentration of 

dissolved iron for the forebay was 20 |ig/L 

compared with 8.3 ng/L and 4.2 ^g/L for the Salt 

bay and Tonto arm, respectively. The mean 

concentration of dissolved manganese for the 

forebay (114 jig/L) was more than two times that 

of the Salt bay (46 ^g/L). This increase in 

concentration may be due to the greater thickness of 

the hypolimnion at the forebay, resulting in a larger 

reducing zone where metals desorb from sediments. 

The mean concentrations of dissolved copper and 

strontium were greatest for the Salt bay. The mean 

concentration of dissolved barium was greatest for 

the Tonto arm.

Water-Quality Standards

Several samples from Roosevelt Lake exceeded 

ADEQ (Arizona Department of Environmental 

Quality, 1992c) water-quality standards for arsenic 

and beryllium and USEPA (U.S. Environmental 

Protection Agency, 1992) secondary maximum 

contaminant levels (SMCL's) in drinking water for 

chloride and dissolved solids (table 7). Several 

water samples from the two major tributaries, the 

Salt River and Tonto Creek, exceeded the ADEQ 

standard for arsenic. In addition, some of the Salt 

River samples exceeded the ADEQ standards for 

beryllium and turbidity and exceeded the USEPA

SMCL for dissolved solids. Additional data for 

Pinal Creek, a tributary of the Salt River, are 

provided to illustrate a potential source of metals 

and dissolved solids to the Salt River upstream from 

Roosevelt Lake, although samples were not 

collected for this study. Several samples from the 

streamflow-gaging station, Pinal Creek at Setka 

Ranch near Globe (09848380), collected from 

September 1990 to May 1992, exceeded or were 

outside the range of ADEQ water-quality standards 

for beryllium, manganese, nickel, dissolved 

oxygen, and pH, and exceeded the USEPA SMCL 

for dissolved solids.

Arsenic concentrations exceeded standards in 3 

of 48 samples collected from the three lake sites. 

The three dissolved-arsenic concentrations that 

exceeded standards ranged from 4 to 6 |ig/L. The 

sample concentrations exceeded the total-arsenic 

standard of 3.1 ^g/L for fish consumption but did 

not exceed standards for domestic-water source 

(50 Mg/L) or other protected uses. Arsenic 

concentrations in Roosevelt Lake generally were 

within the water-quality standards.

Beryllium concentrations are known to have 

exceeded standards in 5 of 44 samples analyzed at 

the three lake sites. Only five dissolved-beryllium 

concentrations were detected at or above the 

laboratory detection limit of 0.5 Mg/L, which is 

above the water-quality standards. Beryllium values 

in Roosevelt Lake ranged from less than 0.5 to 

0.7 Mg/L. The standards for protected uses that were 

exceeded included the standard of 0.008 Mg/L for 

domestic-water source, the standard of 0.21 

for fish consumption, and the standard of 0. 

for full-body contact. Because the laboratory 

detection limit was greater than the standards, all 

detected values exceeded standards. The beryllium 

analyses could not be adequately applied to the 

standards because some of the samples may have 

contained concentrations that were below the 

analytical-detection limit but above the standard. 

Further investigation is needed to determine what 

proportion of these metals is due to human activity 

rather than from naturally occurring conditions.

The USEPA SMCL for chloride was exceeded 

in 8 of 48 samples collected at the three lake sites. 

Chloride concentrations ranged from 90 to 

450mg/L, and the mean value was 230 mg/L, 

which is below the USEPA SMCL for chloride 

(250 mg/L).

Results of Limnologlcal Reconnaissance, 1990-92 29
Table 7. Analyses from the limnological reconnaissance and Final Creek at Setka Ranch, Arizona, 1990-92, that 

exceeded or were outside the range of water-quality standards

[(ig/L, micrograms per liter; mg/L, milligrams per liter; FC, Fish consumption; DWS, Domestic-water source; FBC, Full-body contact; NTU, 

nephelometric turbidity units; A&Ww, Aquatic and wildlife, warm-water fishery; Agl, Agricultural irrigation; A&W, Aquatic and wildlife]

Site Constituent

Water 

use

Water-quality 

atandard

Percent of 

samples 

Maximum exceeding or 

measured outside range 

value of atandard

Number of 

sample 

analyses

Arizona Department of Environmental Quality water-quality standards

Roosevelt Lake

Arsenic, total, ug/L

Beryllium, total, ug/L

Beryllium, total, ug/L 

Beryllium, total, ug/L

FC

DWS

FC 

FBC

3.1

.008

.21 

.33

«6

.7

.7 

.7

6

11

11

11

48

44

44 

44

U.S. Environmental Protection Agency secondary maximum contaminant levels for drinking water

Chloride, dissolved, mg/L

Dissolved solids, mg/L

250

500

450

1,100

17

33

48

48

Arizona Department of Environmental Quality water-quality standards

Salt River

Arsenic, total, ug/L

Beryllium, total, ug/L 

Turbidity, NTU

FC

FC 

A&Ww

3.1

.21 

50

7

«6 

170

60

25 

40

5

4 

5

U.S. Environmental Protection Agency secondary maximum contaminant level for drinking water

Tonto Creek

Dissolved solids, mg/L 500 1,470

Arizona Department of Environmental Quality water-quality standard

Arsenic, total, ug/L FC 3.1 4

60

20

5

5

Arizona Department of Environmental Quality water-quality standards

Final Creek at

Setka Ranch

Beryllium, total, ug/L

Manganese, total, mg/L

Nickel, total, mg/L

Dissolved oxygen, mg/L

pH, standard units

pH, standard units

FC

Agl

FC

A&Ww

FBC

A&Ww

.21

10.0

.4

>6.0

minimum 6.5 

maximum 9.0

minimum 6.5 

maximum 9.0

(i>2

100

1.1

7.0

6.6

6.6

27

100

100

45

73

73

11

11

10

11

11

11

U.S. Environmental Protection Agency secondary maximum contaminant level for drinking water

Dissolved solids, mg/L 500 5,640 100 11

Dissolved-constituent concentration.

30 Hiatorlcal Overview and Umnologlcal Reconnaissance of Theodore Rooaevelt Lake, Arizona
The USEPA SMCL for dissolved-solids 

concentration in drinking water was exceeded in 16 

of 48 samples collected at the three lake sites. 

Dissolved solids ranged from 285 to 1,100 mg/L, 

and had a mean value of 557 mg/L, which exceeded 

the USEPA SMCL for dissolved solids (500 mg/L).

Bottom-Sediment Metals

Although 43 percent of the analyses of bottom 

sediment for specific metals had values less than the 

detection limits, mean values were calculated for 

selected metals from estimates using robust 

log-probability regressions (Helsel and Cohn, 1988; 

table 8, this report). Concentrations of cadmium, 

lead, mercury, selenium, and silver in bottom 

sediment from the stream sites were less than the 

detection limits. Concentrations of lead, mercury, 

and selenium in bottom sediment from the lake sites 

were less than the detection limits. Summary 

statistics were not calculated for iron or manganese 

because several samples contained concentrations 

of these constituents that exceeded the maximum 

reporting level for the laboratory analytical method. 

Measured concentrations of iron ranged from 

51 to more than 13,000 jjg/g and measured 

concentrations of manganese ranged from 14 to 

more than 1,800 Mg/g- Measured concentrations of 

arsenic ranged from 2 to 7 Mg/g and concentrations 

were less than the detection limit in 22 of the

27 samples. Barium concentrations were measured 

in one sample from each site and ranged from

28 Mg/g at Tonto Creek to 80 Mg/g at the Salt arm.

The mean concentrations of chromium, copper, 

and zinc in bottom sediment were greater for stream 

sites than for lake sites. The mean concentration of 

chromium was slightly greater for bottom sediment 

from the stream sites (16 Mg/g) wan for bottom 

sediment from the lake sites (13 Mg/g)- The mean 

concentration of copper for the stream sites 

(163 Mg/g) was considerably greater than the 

median for the lake sites (33 Mg/g); however, the 

median concentration of copper for the stream sites 

(5.5 Mg/g) was less than the median for the lake sites 

(20 Mg/g).

Within the lake, bottom sediment from the 

Tonto arm had the greatest mean concentrations of 

chromium, copper, nickel, and zinc. Bottom 

sediment from the forebay had the greatest median

concentrations of chromium and nickel. Bottom 

sediment from the Tonto arm and the forebay had 

the greatest median concentrations of zinc. Bottom 

sediment from the Salt bay had the greatest median 

concentration of copper.

The mean concentrations of metals in bottom 

sediment from the Salt River were greater than 

those in bottom sediment from Tonto Creek. The 

mean concentration of zinc was two times greater 

for the Salt River (48 Mg/g) than for Tonto Creek 

(22 Mg/g)- The maximum concentration of nickel 

for the Salt River (20 Mg/g) was twice that for Tonto 

Creek (10 Mg/g).

Concentrations of metals in bottom sediment 

from the stream sites varied seasonally during the 

study. At the Salt River site, the greatest 

concentrations of copper, manganese, and zinc were 

found in samples collected in August 1991. The 

copper concentration was 1,200 Mg/g m August 

1991; the second greatest concentration (80 Mg/g) 

was in December 1991. The greatest manganese 

concentration for Tonto Creek (180 Mg/g) occurred 

in May 1992.

Samples collected during the ADEQ study in 

1989 yielded greater metal concentrations than the 

mean values from this study except for copper on 

the Tonto arm. The nickel concentration in 1989 for 

the forebay (55.7 Mg/g) was three times greater 

than the mean concentration for 1992 (17 Mg/g)- 

The copper concentrations in 1989 for the 

forebay and Salt inflow were 84.5 and 87.5 Mg/g. 

respectively; the mean copper concentrations in 

1992 for the forebay and Salt inflow were 23 and 

20 Mg/g, respectively. The copper concentration in 

the bottom sediment from the Tonto arm was 

39.5 Mg/g in 1989 compared with the mean value of 

68 Mg/g for 1992.

SUMMARY AND CONCLUSIONS

The water quality of Roosevelt Lake, a 

reservoir on the Salt River and Tonto Creek, 

potentially could be affected by contamination 

from the Final Creek drainage basin and other 

upstream areas. Ground water in parts of the Final 

Creek basin contains elevated concentrations of 

manganese, copper, and other metals and 

contributes to the flow of Final Creek, which is a 

tributary of the Salt River.

Summary and Conclusions 31
Table 8. Statistical summary of selected metal concentrations in bottom-sediment samples from the limnobgical 

reconnaissance of Theodore Roosevelt Lake, Arizona, 1990-92

[jig/g, micrograms per liter, ND, not detected]

Chromium

Site

Copper

(MS/9)

Nickel Zinc

(MS/9)

Salt inflow

Median............................................................................................ 9.5

Mean............................................................................................... 9.5

Standard deviation.......................................................................... 3.7

Number of samples ........................................................................ 4

Percent of samples with concentration below detection limit....... 0

Salt arm

Median............................................................................................ 5.5

Mean............................................................................................... 8.7

Standard deviation.......................................................................... 8.5

Number of samples........................................................................ 4

Percent of samples with concentration below detection limit....... 25

Salt bay

Median............................................................................................ 12

Mean............................................................................................... 13

Standard deviation.......................................................................... 3.9

Number of samples ........................................................................ 4

Percent of samples with concentration below detection limit....... 0

Tonto arm

Median............................................................................................ 12

Mean............................................................................................... 19

Standard deviation.......................................................................... 15

Number of samples........................................................................ 4

Percent of samples with concentration below detection limit....... 0

Forebay

Median............................................................................................ 16

Mean............................................................................................... 18

Standard deviation.......................................................................... 5.7

Number of samples........................................................................ 3

Percent of samples with concentration below detection limit........ 0

20

20

8.1

4

0

17

27

32

4

25

30

26

15

4

0

25

68

95

4

0

20

23

5.8

3

0

8.5

8.3

1.8

4

0

6.5

9.0

8.1

4

25

10

12

6.0

4

0

10

18

15

4

0

20

17

5.8

3

0

15

18

9.6

4

0

12

17

18

4

25

25

21

13

4

0

30

30

8.2

4

0

30

27

5.8

3

0

32 Historical Overview and LJmnoiogical Reconnaissance of Theodore Roosevelt Lake, Arizona
Table 8. Statistical summary of selected metal concentrations in bottom-sediment samples from the limnological 

reconnaissance of Theodore Roosevelt Lake, Arizona, 1990-92 Continued

Site Chromium Copper Nickel Zinc

Wo)

All lake sites

Median........................................................................................... 11 20 10 20

Mean.............................................................................................. 13 33 12 22

Standard deviation......................................................................... 8.6 45 8.6 12

Number of samples........................................................................ 19 19 19 19

Percent of samples with concentration below detection limit....... 5.3 5.3 5.3 5.3

Salt River

Median........................................................................................... 13 45 11 35

Mean.............................................................................................. 16 325 13 48

Standarddeviation......................................................................... 12 584 5.0 38

Number of samples........................................................................ 4 444

Percent of samples with concentration below detection limit....... 25 0 25 0

Tonto Creek

Median........................................................................................... 12 ND 8.5 20

Mean.............................................................................................. 15 ND 8.5 22

Standarddeviation......................................................................... 9.2 ND 2.1 5.0

Number of samples........................................................................ 4 444

Percent of samples with concentration below detection limit....... 25 100 50 0

All stream sites

Median........................................................................................... 12 5.5 9.5 20

Mean.............................................................................................. 16 163 10 35

Standarddeviation......................................................................... 10 420 4.1 28

Number of samples........................................................................ 8 888

Percent of samples with concentration below detection limit....... 25 50 38 0

The following significant results were observed 

from historical studies and the limnological 

reconnaissance:

ASU, 1970-71

 Roosevelt Lake is a warm, monomictic 

reservoir.

 Phosphate values ranged from 0.01 to 

2.8 mg/L, indicating eutrophy.

USEPA, 1975

 Roosevelt Lake is mesotrophic.

 Primary nutrient limitation by nitrogen 

occurred during sampling; however, the

Summary and Conclusions 33
algal assay test indicated phosphorus 

limitation.

SRP study, 1980-90

 Major-ion concentrations indicate that 

Roosevelt Lake is chemically influenced 

more by the Salt River than by Tonto 

Creek.

 The semilog-regression analysis for 

discharges from the Salt River resulted in a 

moderate r2 value of 0.79 for chloride and 

0.73 for sodium. On the basis of stream 

inputs, discharge is not a good predictor of 

water chemistry leaving the dam.

ADEQ, 1989

 Contaminants detected in the three 

sediment samples included antimony, 

arsenic, beryllium, chromium, copper, 

lead, nickel, and zinc.

USGS limnological reconnaissance, 1990-92

 Roosevelt Lake begins thermal 

stratification in February and becomes 

strongly stratified by April. Temperature 

and specific-conductance data indicated 

that thermal turnover was completed by 

December, but the dissolved-oxygen data 

were more indicative of stratified 

conditions.

 Overall, Roosevelt Lake is considered to 

be mesotrophic. However, chlorophyll-a 

concentrations ranged from 0.70 to 

14 \ig/L, and the mean concentration was 

2.8 [ig/L, indicating oligotrophy. The 

Secchi-disc depth ranged from 1.1 to 

3.0m, and the mean depth was 1.9 m, 

indicating eutrophy.

 Concentrations of dissolved arsenic, iron, 

manganese, nickel, and strontium were less 

in the lake than in the streams. The mean 

concentration of dissolved manganese was 

54 \iglL for the lake sites and 236 \ig/L for 

the stream sites. Mean concentrations of 

dissolved copper and zinc were greater for 

the lake sites than for the stream sites,

whereas mean concentrations of barium 

were equal.

 Of the lake sites, the forebay had the 

greatest mean concentrations of dissolved 

arsenic, iron, manganese, and zinc. These 

greater concentrations may be due to the 

greater thickness of the hypolimnion at the 

forebay, resulting in a larger reducing zone 

where metals desorb from sediment.

 Several samples from Roosevelt Lake 

exceeded ADEQ water-quality standards 

for arsenic and beryllium concentrations 

and USEPA SMCL's for chloride and 

dissolved-solids concentrations.

 The mean concentrations of chromium, 

copper, and zinc were greater in bottom 

sediment from stream sites than from lake 

sites. The mean concentration of copper 

was 163 \ig/g for bottom sediment from 

stream sites and 33 \ig/g for bottom 

sediment from lake sites. The mean 

concentrations of chromium, copper, 

nickel, and zinc in bottom sediment from 

the Salt River were greater than 

concentrations of these constituents in 

bottom sediment from Tonto Creek.

 Of the three lake sites, sediment from the 

Tonto arm had the greatest mean 

concentrations of chromium, copper, 

nickel, and zinc.

Because much of the research on Roosevelt 

Lake has been done on surface samples rather than 

samples from varying depths, a thorough 

limnological evaluation of trends cannot be made 

using existing data. Bottom-sediment cores would 

provide data that could indicate the type and 

magnitude of historical environmental influences 

on Roosevelt Lake. The following approaches used 

in further study of Roosevelt Lake would provide 

information necessary for evaluating the 

limnological processes.

1. Continue to develop a baseline data 

set by which quantitative limnological 

interpretations can be made.

2. Evaluate the effects of increased lake 

elevation on limnological processes.

34 Historical Overview and Limnological Reconnaissance of Theodore Roosevelt Lake, Arizona
3. Evaluate effects of metals loading from 

Final Creek on Roosevelt Lake.

4. Continue to study reducing conditions in 

the hypolimnion as they affect the 

dynamics and recirculation of metals from 

bottom sediment back into ihe water 

column.

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36 Historical Overview snd Umnologlcai Reconnaissance of Theodore Roosevelt Lake, Arizons