9343

• UCREFRP Catalog Number: 9343
• Author: Greve, A. I., N. E. Spahr, P. C. Van Metre and J. T. Wilson.
• Title: Identification of Water-Quality Trends Using Sediment Cores from Dillon Reservoir, Summit County, Colorado.
• USFW Year: 2001.
• USFW - Doc Type: Denver.
• Copyright Material: NO

CONTENTS

Foreword............................................................................................................................................... .................................
III

Abstract...................................................................................................................... ............................................................
I

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

Purpose and Scope................................................................................................................................................ ....... 2

Acknow ledgments ............................................................................................................................................. .......... 2

Descri ption of Study Area........................................................................................................................................... 2

Tenmile Creek.................................................................................................................................................... 4

Snake River........................................................................................................................................................ 4

Blue River............................................................................................................................................ .............. 5

Study Methods........................................................................................................................................ ...............................
5

Reservoir Bottom-Sedi ment Core Samples ................................................................................................................. 5
Streambed-Sediment Samples..................................................................................................................................... 7

Water Samples.................................................................................................................................................. ........... 7

Data Analysis...................................................................................................................................... ......................... 8

Qual i ty-Control Samples............................................................................................................................................ . 8

Sediment Cores.................................................................................................................................................. 8

S tream- Water Sampling..................................................................................................................................... 9

Reservoir-Water Sampl i ng................................................................................................................................. 10

Identification of Water-Quali ty Trends.................................................................................................................................. 10
Pesticides and Polychlorinated Biphenyls in Reservoir-Sediment Cores .................................................................... 10
Polycyclic Aromatic Hydrocarbons in Reservoir-Sediment Cores ............................................................................. 10
Trace Elements in Reservoir-Sediment Cores, Stream-Sediment, and Water Samples............................................... II

Summary and Concl usions ............................................................................................................................................. ....... 20

References Cited............................................................................................................................................. .......................
21

Appendix.......................................................................................................................................... ......................................
23

FIGURES

I. Map showing Dillon Reservoir drainage area and associated land use/land cover .................................................... 3
2. Map showing Dillon Reservoir and tributary sampling sites...................................................................................... 6
3-6. Graphs showing:
3. Five polycyclic aromatic hydrocarbon components plotted against depth in core DLN ................................... 12
4. Concentrations of selected trace elements in Dillon Reservoir core DLN compared to the
Canadian Sediment Quality Guidelines ............................................................................................................. 13
5. Concentration plotted against estimated year of deposition for trace elements that displayed
a concentration spike in the late 1970's and early 1980's .................................................................................. 16
6. Concentrations of trace elements in clay-normalized sediment cores from the mouth of the
streams to the dam at Dillon Reservoir, 1997 .................................................................................................... 19
7. Evidence of bank erosion on Dillon Reservoir, Colorado .......................................................................................... 20

TABLES

I. Presence of dichlorodiphenyldichloroethylene (DDE) and dichlorodiphenyldichloroethane (DDD)
in core DLN collected in August 1997.................................................................................................................... 10
2. Kendall's tau results for five polycyclic aromatic hydrocarbon components paired with core depth
for core DLN, collected near the dam in Dillon Reservoir, August 1997............................................................... II
3. Trace-element concentrations from cores taken in the arms of Dillon Reservoir, and the top 4 centimeters
of the core taken near the dam, August 1997, compared to Canadian Sediment Quality Guidelines..................... 14
4. Results of Kendall's tau calculations relating trace-element concentrations to core depth in core DNL,

collected August 1997 ............................................................................................................................................. IS

5. Load calculations for trace elements entering and leaving Dillon Reservoir for 1997 and 1998 based on
regression analysis of the log of instantaneous flow relative to the log of concentration ....................................... 17
6. Percentage of copper, iron, manganese, molybdenum, and zinc loads in the dissolved phase entering
and leaving Dillon Reservoir, water year 1997 ....................................................................................................... 18

CONTENTS V