Environmental Impact of Impoundment of the Snake Creek Reservoir Keith Rice, Bryan Victor, Dr. Julie K. Bartley, and Dr. Rebecca Dodge; Department of Geosciences, University of West Georgia, Carrollton GA 30118

Landsat Satellite Images

1999 2001 2003

1999 2003

Water Quality

Upstream-Site 49 Downstream-Site 111

Unsupervised Classifications

2001

Change Detection1999-2003 2001-2003

Background

The Snake Creek Reservoir was impounded in late 2001. It is located just east of Carrollton Georgia and provides part of the county’s drinking water supply. It is the newest and largest reservoir in Carroll County.

Concerns •Temperature will increase in flooded areas, due to decreased flow and increased surface area.

•Turbidity will increase due to upstream erosion. The reservoir will gradually fill with sediments.

•Dissolved oxygen levels will become lower and may result in a fish kill, upstream of the reservoir.

•Bacterial activity will increase.

Project Goals

Assess environmental and water quality change during and after impoundment. Data sources: Landsat satellite (1999, 2001, 2003); water quality data from the Center for Water Resources (2001, 2004), and from USGS (2001), and newly collected data during the project.

Temperatures at Site 49

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40

1/1/01 1/1/02 1/1/03 1/1/04 12/31/04

Date

Te

mp

era

ture

(°C

)

Air Temperature

Water Temperature

Turbidity at Site 49

0

5

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15

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10/01/00

04/19/01

11/05/01

05/24/02

12/10/02

06/28/03

01/14/04

08/01/04

02/17/05

09/05/05

Date

NT

U

2004

2001

Dissolved Oxygen at Site 49

4

6

8

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16

02/19/00 11/20/00 08/22/01 05/24/02 02/23/03 11/25/03 08/26/04 05/28/05

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mg

/L

2004

2001

Water Temperature at Site 111

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12/6/99 4/19/01 9/1/02 1/14/04 5/28/05

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ture

(°C

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2004

Turbidity at Site 111

0

5

10

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12/6/1999 4/19/2001 9/1/2002 1/14/2004 5/28/2005

Date

NTU

2001 Site 111

2004 Site 111

Dissolved Oxygen

4

6

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10

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14

16

12/6/1999 4/19/2001 9/1/2002 1/14/2004 5/28/2005

Date

mg/

L

2001 Site 111

2004 Site 111

These three scenes capture the intervals of the reservoir impoundment. The central portion of the subset, shows substantial change from 1999 to 2001 and again from 2001 to 2003. (Green represents vegetation; pink shows areas of bare ground; and black represents water) The image is 17.16 km wide.

These images evaluate change between two time intervals. Green represents a ≥20% increase in reflectance and the red shows a ≥20% decrease in reflectance. Black areas show <20% change. The 1999 image was taken during a drought, causing change to appear anomalously high.

Conclusion•Satellite images show substantial change over the study period. Pre-impoundment clear cutting and subsequent impoundment are visible. •Water temperature increase upstream of the reservoir contributes to a drop in dissolved oxygen. •Upstream increase and downstream decrease in turbidity is consistent with sediment erosion and entrapment in the reservoir. Over time, the reservoir will accumulate sediment, decreasing its volume. •Fecal coliform bacteria levels show a pattern similar to turbidity, consistent with increased runoff and higher temperature upstream of the reservoir, and entrapment of sediment in the lake.

The images above group areas of similar land cover to better visualize land use change from year to year. Green=Grass, Orange=Bare Ground, Turquoise=Evergreen Trees, Dark Green=Deciduous Trees, Blue=Water, Pink=Residential, Red=Roads, and White=Clouds

Acknowledgements: John Congleton, Randa Harris, Curtis Hollabaugh, Patrick Gilliland and Andrew Boothe. Funded by: NSF STEP grant #  DUE-0336571 

Temperature is higher after impoundment at both sites. After impoundment, summer water temperature exceeds air temperature.

Average turbidity is higher upstream after impoundment and lower downstream. Note that clear-cutting had begun in the reservoir area by 2001.

Dissolved Oxygen is lower after impoundment, upstream of the reservoir.

Fecal coliform bacteria levels are higher upstream after impoundment and lower at the downstream sites (site 50 is downstream from site 111).

Fecal Coliform

0100200300400500600700800900

11/10/2000 9/6/2001 7/3/2002 4/29/2003 2/23/2004 12/19/2004 10/15/2005

Date

Colon

ies pe

r 100

mL

2001 Site 502004 Site 111

Fecal Coliform

0100200300400500600700800900

11/10/00 09/06/01 07/03/02 04/29/03 02/23/04 12/19/04 10/15/05

Date

Colon

ies pe

r 100

mL

2004 Site 49

2001 Site 49