News From The River

See the Latest Water Quality Monitoring Data from the FoRR Monitoring Team!

FoRR took to the river last week on June 27 and 28 to monitor five sites in the Reedy River watershed. Our sites include the following:

Site #1: Reedy River just downstream of Swamp Rabbit Cafe

Site #2: A small tributary of the Reedy River in Falls Park 

Sit #3: Reedy River on Mauldin Road upstream of ReWa's headquarters

Site #4: Reedy River on Greenville Tech's Brashier campus in Simpsonville

Site #5: Reedy River in Cedar Falls Park in Simpsonville

We were a bit later in the month than usual due to the heavy rains during our normal monitoring week. The SC Adopt-a-Stream program dictates that volunteers should not monitor within 24 hours of a significant precipitation event. Sites 1 through 3 in the Greenville area were monitored on Tuesday June 27. Sites 4 and 5 in the Simpsonville area were monitored on Wednesday, June 28.

The pH results for June were consistent with our findings in May, with sites showing only small changes of 0.5 or less, if any change was present at all from last month’s results. 

The air and water temperatures for June’s sampling event increased again, as expected through the summer months. The air temperatures across all sites increased by an average of 3.8C, with June’s sampling event average temperature being 23.1C compared to last month’s average temperature of 19.3C. The air temperatures ranged from 21.5C (Falls Park) to 25C (Cedar Falls Park). The water temperatures also increased in June, with the average water temperature at our sites increasing from 18.8C in May to 20.62C in June. The water temperatures ranged from 18.5C (SRC) to 23.6C (Greenville Tech Brashier). 

June’s dissolved oxygen (DO) results ranged from 6.2 mg/L to 7.3 mg/L. Overall, the DO levels dropped by an average of 0.82 mg/L across all sites. The site that changed the least was Falls Park, which only dropped by 0.4 mg/L, but Greenville Tech Brashier decreased by 1.3 mg/L from last month’s results. This can be attributed to the high water temperature increase at Greenville Tech Brashier (3.6 C) because water temperature and dissolved oxygen levels have an inverse relationship. Warmer water has less capacity to hold dissolved oxygen, so when water temperatures increase, dissolved oxygen levels decrease. We can attribute the overall decrease in DO levels across all sites to this relationship with water temperature, and do not expect to see DO levels rise again until temperatures decrease in the fall.

The E. coli bacteria results varied in trends, with three sites showing decreases in E. coli levels from last month and two sites increasing. The E. coli CFU levels at our Falls Park site increased significantly by 366.33 CFU/100mL, with the levels in June reaching 533 CFU/100mL. This is above the state-defined “high threshold” of 349 cfu/100mL, but is not problematic. The increase in levels at Falls Park are likely caused by increased water temperatures, pet traffic, and waterfowl activity. Greenville Tech Brashier’s E. coli counts also increased in June, but the results are well below the “high” threshold at only 266 CFU/100mL. Despite the E. coli increases at these two sites, the levels decreased at the other three sites: Swamp Rabbit Café, Mauldin Road, and Cedar Falls Park. We were especially pleased to see the levels at Cedar Falls Park drop by 167 CFU/100mL and return to a more normal level of 233 CFU/100mL in June. When we monitor in July, we will be sure to closely monitor the levels at Falls Park to ensure it returns to normal levels as well, while understanding that high water temperatures and high levels of sedimentation from erosion after strong rainfalls can contribute to higher E. coli levels through the summer especially when combined with high concentrations of waterfowl and pet waste. 

FORR has begun sampling water transparency by using a transparency tube, which quantifies the clearness (or clarity) of water. Color, algae, and suspended sediments can alter this result. In the Reedy, transparency is most likely to be impacted by sediments in the water column due to high runoff rates and failing streambanks due to the urban nature of our watershed. This measure of transparency can be converted and utilized to approximate water turbidity, which is a measure of the cloudiness of water. Turbidity can impact photosynthesis and water temperature and can be indicative of too much unmanaged stormwater runoff in the watershed. Turbidity is quantified with the unit of measurement “NTU,” which stands for “Nephelometric Turbidity Units”. Low NTU readings indicate clearer water and high readings indicate very turbid, or cloudy, water. NTU readings typically range from 1 to 4,000, with 1 being clear water and 4,000 having very little transparency and high turbidity (think of the cloudiness of milk). 

June’s turbidity at our five sites ranged from 5 NTU to 12 NTU, with most sites within the range of 5 to 6 NTU (fairly clear water). Cedar Falls Park had the highest turbidity level at 12 NTU, likely because of sediment loading in the river. This is much less turbid than the Cedar Falls Park’s turbidity reading last month of 27 NTU, so it is an improvement. We will continue to monitor trends in turbidity across all sites as we collect more data in the coming months.

June’s results and the SC state standards are included for comparison below. All results were within SC state standards. 

June 2023 Monitoring Results:

  • pH is a way of measuring the H+ ions in a water sample, or if the sample is acidic or basic. pH is influenced by the concentration of acids in rain, and the types of soils and bedrock present in the watershed. Ideally, rivers will have a neutral pH, or a value of 7.
  • The available dissolved oxygen (DO) in a water sample is important for fish health and life within a body of water. DO can increase in lower temperatures, turbulence in the water, photosynthesis in the stream, and diffusion from the atmosphere. DO can decrease in higher temperatures, in slow-moving and deep water, and in the presence of decaying organic matter.
  • Conductivity is the ability of the water to pass an electric charge and shows the presence of ions in the water, such as salt, nitrate, phosphate, and many others. The bedrock in the watershed can also affect conductivity
  • E. coli Bacteria counts are found by incubating a water sample that was placed on a medium, then counting the number of coliform forming units. These values are higher in areas where animals are present so always remember to pick up after your pets and don't feed the geese in the park!
  • Turbidity, the cloudiness of water, is quantified with the unit of measurement “NTU,” which stands for “Nephelometric Turbidity Units”. Low NTU readings indicate clearer water and high readings indicate very turbid, or cloudy, water. NTU readings typically range from 1 to 4,000, with 1 being clear water and 4,000 having very little transparency and high turbidity (think of the cloudiness of milk). 

Sign up to join the FoRR monitoring team HERE!

Find an SC Adopt-a-Stream event near you to become certified HERE!

The FoRR Monitoring Team uses SC Adopt-a-Stream techniques and has its own monitoring kits, thanks to Ivy Salon and The Greenville Zoo Conservation Fund.

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