Station II (r = 0.68) and Station III (r = 0.56) and a 

 nonsignificant correlation at the Reference Station 

 (r^ = 0.33). The correlations were based the total 

 precipitation and flow experienced at the stations 

 between sampling periods. However, on two 

 occasions, sampling dates were only two months apart 

 (November 1997/January 1998 and December 

 1998/January 1999). For these two periods, flow and 

 precipitation for the three months prior to the 

 sampUng date were considered. 



At the Reference Station, salinity values greater than 

 35 ppt (seawater concentration) were recorded 22% of 

 the time, while values less than 18 ppt were measured 

 56% of the time. The highest salinity (53 ppt) 

 occurred in February 1997 during a five-month period 

 with less than 25.2 cm (10 inches) of rain. The lowest 

 values recorded coincide with periods having heavy 

 rainfall. For example, a salinity value of 13 ppt was 

 recorded in June 1997, following three months with 

 over 37.8 cm (15 inches) of rain. However, salinity 

 increased rapidly afterwards to 43 ppt in August 1997. 

 A salinity value of 12 ppt was recorded in December 

 1998, following four months with over 55.4 cm 

 (22 inches) of rain. In this instance, salinity remained 

 relatively low throughout 1999, most likely because 

 spring rains were abundant, with the highest salinity for 

 the year (23 ppt) being recorded in June 1999. 



At Station II, open water salinity values above 35 ppt 

 were recorded on three sampling dates (25% of the 

 samples), with the highest recording being 65 ppt in 

 February 1997. Low values recorded at this station 

 occurred on the same dates as those at the Reference 

 Station. Values after major hydrographic events 

 flooding the Rincon Overflow Channel do not differ 

 by more than 1 ppt from those at the Reference 

 Station but were 5 ppt lower than Station III after the 

 October 1998 and September 1999 events. 



Station III had the greatest number of readings higher 

 than 35 ppt (35%). The relatively higher values may be 

 reflective of its closer proximity to Nueces Bay. The 

 highest value (57 ppt) was recorded in May 1996, 

 following six months of less than 5 cm (2 inches) total 

 rainfall. 



Pore Water Salinity 



Pore water salinity values were typically higher than 

 those in open water (Table 6-2 and Figure 6-4b). At 

 the Reference Station, pore water salinity 

 concentrations ranged between 20 and 87 ppt and were 

 as much as 14 times higher than the open water salinity 

 value measured on the same date. At Station II, values 

 ranged between 8 and 85 ppt and were as much as 16 

 times higher than the open water value. The range of 

 values at Station III was similar to the other stations 

 (1 1 to 92 ppt) but was measured to be only as much as 

 3 times higher than the open water value. 



Pore water values did not always decline after a 

 hydrographic event, whether the event was 

 precipitation- or flow-mediated (Figure 6-4b). 

 However, as many of the values are missing, 

 determination of actual decrease proved difficult. 

 Additionally, sampling dates did not always 

 immediately follow times of heavy precipitation or flow 

 events. Consequentiy, salinity values might have 

 decreased, but unless the sampling date occurred soon 

 after the freshwater input, any pore water response 

 might not have been measured. 



On the occasions that values could be recorded, the 

 response was variable. In December 1998, following 

 three months with over 25 cm (10 inches) rainfall, pore 

 water salinity values at the Reference Station decreased 

 by 9 and 26 ppt at two locations (0 and 49 m). 

 However, values at Station II were only reduced at m 

 (the location closest to open water) and only by 6 ppt, 

 despite the flooding of the station during the October 



1998 event. In contrast, pore water salinity values 

 decreased at Station II in September 1999 by 36, 58 

 and 42 ppt at 0, 49 and 99 m locations, respectively. 

 The decrease immediately followed the September 



1999 event, which had not yet activated the Rincon 

 Overflow Channel but did see over 15 cm (6 inches) 

 rain in one day. During this event, a tidal surge from 

 the bay flooded the transects, flushing the soils and 

 then retreating after the surge. In this instance, the 

 sampHng date was only days following the event. The 

 spring and summer months also had relatively high 



Chapter Six ♦ 6-11 



