The pH results for September were the same as or consistent with last month's findings, showing very minor fluctuations, if any. Two of our five sites showed no change at all from August’s results.
The air and water temperatures for all sites are continuing a decreasing trend with an average air temperature of 21.8℃ and average water temperature of 19.4℃ (avg. decreases of 1℃ air temperature and 2.4℃ water temperature since the last sample date in mid-August).
The increased dissolved oxygen (DO) levels have an inverse correlation with the decreased water temperatures. Remember– the lower the water temperature, the higher the water’s capacity to hold dissolved oxygen! This month brought an average DO increase of 0.45 mg/L across all sites. The average DO reading for September was 6.88mg/L with results ranging from 6.1 to 7.5mg/L. The sites that showed the biggest increases in DO were ReWa and Greenville Tech Brashier which both increased 0.6mg/L since August, with Cedar Falls Park close behind with a 0.5mg/L increase. As aquatic-dwelling organisms like fish, reptiles, and macroinvertebrates experience slowing metabolic rates, we anticipate continuing to see DO levels drop throughout the fall and winter months. As metabolisms slow, less oxygen is consumed by aquatic organisms, leaving more DO present in the water. Because cold water also has a higher capacity for dissolved oxygen, we do not expect to see low DO results again until temperatures begin to rise in the spring.
September’s E. coli bacteria results did not follow the expected pattern of continually decreasing E. coli colony forming unit concentrations as temperatures dropped, but instead showed the average E. coli result increasing by 40.2CFU/100mL when compared to August’s results (August: 253.2CFU/100mL. September: 293.4CFU/100mL). While this increase was unexpected, it is not alarming and most sites’ results fell well within the SC state standard “high” threshold of 349CFU/100mL. Our only outlier was the Falls Park site with 567CFU/100mL. We did not see anything onsite that looked as though it would contribute to the E. coli increase (no waterfowl or dog waste), so we will continue to monitor this site closely in the coming months to ensure levels do not continue to rise.
Conductivity levels were not tested this month as the SC AAS program is no longer including this parameter in their monitoring protocol.
We have included this month's results along with SC's state standards for comparison below. All results were within state standards.