Georgia Water Science Center
Urban-Atlanta home | The sampling program
The monitoring network consists of 20 long-term monitoring sites. Ten of the 20 sites are instrumented with a continuous water-quality monitor, water-level sensor, and a raingage to provide water temperature, specific conductance, dissolved oxygen, pH, turbidity, water level, and rainfall data; these parameters are measured at 15-minute intervals. The data are transmitted, via satellite, to the USGS Georgia Water Science Center. In addition, each of these 10 sites is equipped with a programmable automatic sampler.
Two additional sites are equipped to measure water level and rainfall. The remaining eight sites are not instrumented. The data are available via the USGS National Water Information System (NWIS) Web page at http://ga.water.usgs.gov/. The data are also published in the USGS Georgia District Annual Data Report (Alhadeff, S.J., McCallum, B.E., and Landers, M.N. [compilers], 2004).
Manual
The manual sampling program is designed to determine representative water-quality conditions. Because water quality is affected by stream hydrology, attempts are being made to collect samples covering at least 80 percent of the annual hydrograph. Each of the 20 sites is manually sampled 12 times per year. Equal width increment and point samples are collected for chemistry, sediment concentration, bacteria, and sewage tracers. At the 10 sites with automatic samplers, the point samples are collected at the automatic sampler intake and will be used to develop correction factors for the automatic sampler-derived data so that it will be representative of the fluvial cross section. Once collected, the samples are split into raw, filtered, and acidified aliquots for analysis. A water-quality sonde is used to obtain values for water temperature, specific conductance, dissolved oxygen, pH, and turbidity at several points across the sampling section, as well as at the point sample location.
USGS field personnel use standardized methods for sample collection and hydrologic measurements to ensure consistent, unbiased, precise, and comparable data. USGS published guidelines and standard procedures (U.S. Geological Survey, variously dated) for equipment cleaning, sample collection, and sample processing used on the city of Atlanta project. The program incorporates a substantial quality-assurance/ quality-control component to assess the errors associated with sampling, chemical analysis, and measurements.
Automated
Automated, stage-actuated, samplers are used at 10 of the .20 long-term monitoring sites to further increase the coverage of hydrologic events. The samplers are programmed to collect samples when the stage at each site exceeds a predetermined level. The samplers are equipped with twelve 2,000-milliliter bottles. Samples are collected at site-specific time intervals (ranging from 30 minutes to 1.5 hours). The time intervals vary from site to site as well as seasonally. The samplers continue to sample until either the stage falls below the trigger point, or all 12 bottles are filled. The automated sampling equipment is cleaned using the same standardized methods as those used for manual sample collection.
Alhadeff, S. J., McCallum, B.E., and Landers, M.N., (compilers), 2004, Water resources data—Georgia, 2003. Volume 1—Continuous water level, streamflow, water-quality data, and periodic water-quality data, Water Year 2003 [Water Data Report GA-03-1]: Volume 2— Continuous ground-water-level data, and periodic surface-water- and ground-water-quality data, Calendar Year 2003 [Water-Data Report GA-03-2]: U.S. Geological Survey Water-Data Reports GA-03-1 and GA-03-2, CD–ROM, online at http://water.usgs.gov/pubs/wdr/.wdr-ga-03-1/ and http://water.usgs.gov/ pubs/wdr/wdr-ga-03-2/
Joiner, J.K., 2003, New water-quality monitoring efforts in Metropolitan Atlanta, Georgia, in Proceedings of the 2003 Georgia Water Resources Conference, held April 23–24, 2003, at the University of Georgia. Kathryn J. Hatcher, ed., Institute of Ecology, .The University of Georgia, Athens, .Georgia, 117–199, on line at http://ga.water.usgs.gov/pubs/other/gwrc2003/
U.S. Geological Survey, variously dated, National field manual for the collection of water-quality data: U.S. Geological Survey Techniques of Water-Resources Investigations, book 9, chaps. A1–A9, online at http://pubs.water.usgs.gov/twri9A
U.S. Department of the Interior |
U.S. Geological Survey
URL: http://ga.water.usgs.gov/projects/projectatlantasampling.html
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Page Last Modified: Friday, 23-Jun-2006 11:16:42 EDT
