Testing the Waters: South Carolina

There are 63 beaches in South Carolina lining 180 miles of Atlantic coastline (102 miles on the mainland coast and 78 miles on islands without bridges from the mainland barrier islands or on sandbars). The state's beachwater quality monitoring program is administered by the Department of Health and Environmental Control (DHEC).

Using Deep Ocean Outfalls to Protect Swimmers in the Grand Strand

The Grand Strand is a stretch of beaches between Little River and and Georgetown, South Carolina. Some of the Grand Strand communities have constructed stormwater outfalls that discharge deep in the ocean instead of at the beach in order to reduce beach erosion and reduce localized pollution concentrations for swimmers. These projects, which cost millions of dollars per ocean outfall, have created significant reductions in the amount of fecal indicator bacteria found in beachwater where they have been implemented (7th Avenue South in North Myrtle Beach and Deep Head Swash in Myrtle Beach). In 2011, Myrtle Beach completed construction of the latest ocean outfall, located at 4th Avenue North. This project combined nine existing stormwater drainage pipes that used to discharge at the beach into one pipe that runs underneath the seabed and discharges into the Atlantic Ocean more than 1,000 feet from shore.1

NRDC encourages coastal communities to explore solutions that prevent stormwater runoff before it occurs. The high cost of deep-ocean outfalls as a solution to beach erosion and beachwater quality problems illustrates the importance of reducing stormwater runoff by implementing green infrastructure wherever possible. In addition to improving beachwater quality, green infrastructure does not transfer pollution to the ocean and has significant other benefits.

What Does Beachwater Monitoring Show?

In 2011, South Carolina reported 63 coastal beaches. Of these, 1 (2%) was monitored more than once a week, 6 (10%) were assigned a monitoring frequency of once a week, 16 (25%) every other week, and 40 (63%) were not assigned a monitoring frequency. In 2011, 8% of all reported beach monitoring samples exceeded the state's daily maximum bacterial standard of 104 colonies/100 ml. The beaches with the highest percent exceedance rates of the state standard in 2011 were Springmaid Beach (18%), Briarcliffe Acres Beach (13%), Myrtle Beach (13%), Myrtle Beach State Park and Campgrounds (10%), and Garden City Beach (9%), all in Horry County. Beaches in Horry County had the highest exceedance rate of the state standard in 2011 (11%), followed by Colleton (4%), Charleston (3%), Georgetown (1%), and Beaufort (<1%) counties. There were no exceedances in Beaufort County. NRDC considers all reported samples individually (without averaging) when calculating the percent exceedance rates in this analysis. This includes duplicate samples and samples taken outside the official beach season, if any.

* Please note that only samples from a common set of beaches monitored each year from 2007-2011 are included in the bar chart.

What Are South Carolina's Sampling Practices?

The monitoring season in South Carolina is from May 15 to October 15. DHEC determines monitoring locations, sampling practices, standards, and notification protocols, which are uniform throughout the state. Samples are taken in water that is 20 to 40 inches deep, 12 inches below the surface. A sanitary survey (a systematic investigation that is used to identify potential sources of human sewage pollution) is conducted every time a beach is sampled. In South Carolina, beaches are prioritized for inclusion in the monitoring program based on level of use, water quality history, and other applicable factors. Most of the highest-priority (Tier 1) beaches have stormwater outfalls.1

Sampling is deliberately conducted at swashes and outfalls, where water quality is expected to be at its poorest. Portions of beaches whose water quality has fallen below standards are sampled daily. States that monitor more frequently after an exceedance is found will tend to have higher percent exceedance rates and lower total advisory days than they would if their sampling schedule did not increase after an exceedance was found or after heavy rainfall.

In addition to DHEC monitoring, the city of Myrtle Beach uses Coastal Carolina University to conduct year-round sampling at monitoring sites in Myrtle Beach. Thus, during the state's monitoring season, these sites are monitored twice a week. Also, during the monitoring season, the county park on Isle of Palms samples twice per month in addition to DHEC's twice-a-month monitoring schedule, so one of the nine monitoring stations at this beach is monitored four times per month.

How Many Beach Advisories Were Issued in 2011?

Total advisory days for 7 events lasting six consecutive weeks or less increased to 10 days in 2011 from 4 days in 2010. For prior years, there were 48 days in 2009, 36 days in 2008, 108 days in 2007, 684 days in 2006, and 592 days in 2005. In addition, there were no extended or permanent events in 2011. Extended events are those in effect more than six weeks but not more than 13 consecutive weeks; permanent events are in effect for more than 13 consecutive weeks. For the 7 events lasting six consecutive weeks or less, 100% (10) of advisory days in 2011 were due to monitoring that revealed elevated bacteria levels.

How Does South Carolina Determine When to Warn Visitors About Swimming?

The beachwater quality monitoring program has the authority to issue advisories but not closings; in South Carolina, only elected officials can close a beach. South Carolina applies a single-sample maximum standard for enterococcus of 104 cfu/100 ml. No geometric mean standard is applied when determining whether to issue a beach advisory.

DHEC issues an advisory immediately when the enterococcus bacteria level is 500 cfu/100 ml or higher. If the bacteria level is above 104 cfu/100 ml but below 500 cfu/100 ml, an additional sample is collected. If the second sample is also above 104 cfu/100 ml, the department issues an advisory. Advisories include the area of the beach that is within 200 feet on either side of the monitoring station where the exceedance occurred.

A rain model is used for posting preemptive advisories for Horry County's Tier 1 beaches. Sampling results indicated that use of the model might be leading to the issuance of advisories that were not necessary, and work to improve the accuracy of the model was under way in 2011.2 Most pipe outfalls and swashes in Horry County are under permanent rainfall advisory, with permanent signs advising the public against swimming in the area of the stormwater outfall. These types of standing advisories are not reported to EPA and are not included in NRDC's analysis.

Notes

1. South Carolina Department of Health and Environmental Control, "2010 Ocean Water Quality Sampling and Advisory Data Report for U.S. EPA Region IV," November 2010.
2. Jim Hess, South Carolina Department of Health and Environmental Control, personal communication, May 2012.
3. Why don't the 2011 percent exceedance values in this summary match? Only samples from a common set of beaches monitored each year from 2007-2011 are included in the bar chart. Because some beaches were not monitored in each of these years, the percent exceedance for this subset of beaches (7%) did not have the the same value as the percent exceedance for all of the beaches monitored in 2011 (8%).