File Memorandum on Review of Water Quality Changes in Edwards Reservoir-Especially Near the Bad Water Line

Author Harden RW
Year 1968
Description File memorandum on review of water quality from monitoring wells near the bad water line through 1967 Note: Page-size and large-format size of original plate are at the end of the document.
Publisher Edwards Aquifer Authority
Location Edwards Aquifer, Balcones Fault Zone, San Antonio Segment
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This memorandum presents the results of a review of the water quality data for the observation wells through 1967. It also includes some observations on the general water quality of the Edwards. The primary purpose of reviewing the water quality observation well data has been to identify where

and when changes in water quality have occurred and the nature of the changes….


1. The water quality changes in individual wells have to date mostly been small. No large, lateral shift in the position of the bad water line is apparent from the data available, and none is believed to

have occurred in historical times.
2.. The present study indicates that there are considerably more wells in which water quality variations occur than have been recognized, or were recognizable, in the past. This is probably

due mostly to a longer period of record now being available for some of the wells over periods when larger and more prolonged changes in stage of the reservoir have occurred.
3. Wells located very close to the bad water line tend to show larger and more easily recognizable changes in quality than other wells, but some changes in water quality are noted for wells located

some distance both north and south of the bad water line.

4. It does not appear that a more exhaustive study of the bad water line is warranted at present, but additions to the present network of wells sampled, particularly in Bexar County, appear to be


Because of the potential importance to San Antonio of quality changes along the bad water line in Bexar County and inasmuch as quite a few small changes are apparently occurring, it is recommended that additional wells both along the bad water line and south of the bad water line be included in the semi-annual sampling program of the USGS cooperative study. Table 5 lists all the wells in Bexar and Atascosa Counties that we recommend be in the program.

Some of those listed are already a part of the program, and nearly all have been included at one time or another. Each well should be sampled each year in January and August and a preliminary

type analysis made. In addition, a search for additional, existing wells in Bexar County located both close to the bad water line and also south of the bad water line should be made, and probably all

wells found should be added to the program.