The Recreational Water Quality Monitoring Program completed its 13th week of sampling last week. That means we are halfway through the 2014 monitoring season! It’s a good time to stop and take a look back at what we’ve accomplished so far. Here is (half of) the 2014 sampling season by the numbers:
15 sample sites tested weekly
13 weeks of sample collection
195 samples available for collection
188 samples actually collected
7 missed samples (Lady C maintenance & staffing)
97% completeness rate
940 lines of data generated
24 samples exceeded South Carolina’s standard safe swimming
2046 MPN/100 mL highest sample tested
10 MPN/100 mL lowest sample tested
Charleston Harbor 1 (Melton Peter Demetre Park) – Best overall performance
Shem Creek 3 – Worst overall performance
A few things have changed since our wrap up blog post at the end of the 2013 sampling season. First, we added 3 new monitoring sites this year. One site is in Wappoo Creek and the other two are in Hobcaw Creek. See all of our sampling sites here. Second, we began our monitoring season on May 1 this year and will collect nine more weeks of data than we did in 2013. More data gives you more information about how safe your waterways are for swimming and us a better picture of what is happening in the water.
Finally, overall, bacteria concentrations have been lower this year than last year. This is likely a result of less rainfall: we began monitoring in May, but last year we started in July (July, August, and September are on average the wettest months). Remember stormwater runoff picks up pet and wildlife waste and the pathogens they can harbor and discharges it into our waterways making them unfit for swimming. Please pick up after your cat or dog. Our research with the Upper Inlet Creek Project shows that up to 40% of the bacteria in a suburban tidal creek may be from domestic pets.
Taking a closer look at our 2014 data, we can already start to see some trends. James Island Creek 2 and Shem Creek 3 continue to show high readings just like last year. But, some other sites that may be impaired are slipping under the weekly radar. That’s because South Carolina uses a two part water quality standard to determine if waters are “swimmable”.
The first part screens for acute water quality issues and holds that if a single sample exceeds 104 MPN/100 mL the site is unsafe for swimming. This is what we use to report results on a weekly basis. The second part screens for chronic water quality issues over time and holds that if the geometric mean of all samples from a month exceeds 35 MPN/100 mL the site is unsafe for swimming. This is what we use to produce our Recreational Water Quality Scorecard. DHEC also uses this standard to determine if a site is impaired for swimming.
What does this all mean? Some sites that appear to be doing well based on single sample readings may still have long term problems. Sites we are keeping a close eye on:
James Island Creek 1
Shem Creek 1 (Shem Creek Park Public Dock)
Shem Creek 2 (Mill St Public Boat Landing)
Ashley River 2 (Brittlebank Park)
Charleston Harbor 3 (Battery Beach)
Hobcaw Creek 2
You can always find the latest water quality conditions on our website and on Swim Guide. Be sure to keep up with the latest information about the Recreational Water Quality Monitoring Program by following us on Facebook, Twitter, and Instagram! We regularly post about current water quality conditions to help you stay informed!
Finally, we want to give a big THANK YOU to the folks that help keep this program running smoothly! Many thanks to our dedicated team of Field Investigators, Dr. Vijay M. Vulava – Director of the Hydrochemistry Research Lab in the College of Charleston’s Department of Geology and Environmental Geosciences, and City Marina.