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Table 1. Monthly water-quality data collected at monitoring sites near the freshwater/saline-water interface of the Edwards aquifer, July 1996-December 1997

[Number in parenthesis refers to figure 1. SWTSU, Southwest Texas State University; median pH in standard units; T, mean temperature in degrees Celsius; SC, mean specific conductance in microsiemens per centimeter at 25 degrees Celsius; --, no data because of malfunctioning equipment.]


Month (1) SWTSU research well
(2) San Marcos Springs
(3) Comal     Springs
(4) Atascosa municipal well
pH T SC pH T SC pH T SC pH T SC
July 1996  

6.8

22.4

624

 

7.1

22.4 592   -- -- --    
Aug. 1996

7.1

22.4

625

7.1

22.4 609 -- -- --
Sept. 1996  

7

22.4

621  

7

22.4 602  

7.1

23.4 525  
Oct. 1996

7

22.4

624

7.1

22.4 610

7.1

23.4 524
Nov. 1996  

7

22.4

631  

7.1

22.4 611  

7.1

23.4 523   Water-quality monitor
Dec. 1996

7.2

22.4

633

7

22.4 621

7

23.4 526 not installed
Jan. 1997  

--

--

--

 

--

-- --  

7.2

23.4 533   until June 1997
Feb. 1997

7.1

22.4

591

7.1

22.4 607

7.2

23.5 533  
Mar. 1997  

7.1

22.4

592  

7

22.4 606  

7.2

23.4 539  
Apr. 1997

7.1

22.4

614

7.2

22.4 602

7.1

23.4 538
May 1997  

7.2

22.3

618  

7.2

21.5 608  

7.5

23.5 534  
June 1997

7.1

22.4

611

7.2

20.8 609

7.6

23.5 532 --

27

575
July 1997  

7

22.2

601  

7.1

20.5 606  

7.1

23.5 530  

7

27.6

624
Aug. 1997

7

22

604

7.1

20.6 607

7.5

23.5 533

7.1

27.6

630
Sept. 1997  

6.9

21.9

610  

7

20.6 608  

--

23.5 531  

7

27.6

620
Oct. 1997

7

21.8

615

7

20.4 610

7.2

-- --

7.2

27.4

630
Nov. 1997  

6.9

21.8

619  

7.1

20.4 612  

6.8

-- --  

7.2

27.3

630
Dec. 1997

7

21.9

621

7

20.4 614

7.2

23.5 511

6.9

27.3

627

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