More Information about Integrated Water Quality Measure:

One of the goals of SCECAP is to develop integrated measures of habitat quality using multiple parameters that are combined into a single index value.  To develop an integrated water quality measure, six parameters were selected: dissolved oxygen, biochemical oxygen demand, fecal coliform bacteria, total nitrogen, total phosphorus, and pH.  The oxygen measures provide an indication of both oxygen availability and consumption.  The nitrogen and phosphorus measures provide the best indication of possible nutrient enrichment (eutrophication).  Fecal coliform concentrations provide an indication of the suitability of the water for shellfish harvesting and primary contact recreation, and the pH measure provides information on levels that may be stressful for many marine species.  Other parameters, such as turbidity, may be included in the future once additional sampling and analyses have been completed.   

The six water quality variables were each given a score of 1, 3, or 5.  Parameters with a score of 1 (coded as red) indicate either an exceedance of state water quality standards, or if no standards existed, they represent values exceeding the 90^th percentile of SCDHEC’s historical database (SCDHEC, 1998a).  Parameters with a score of 3 (coded as yellow) represent conditions that may be marginal since they either exceeded a portion of the water quality standard or the 75^th percentile of SCDHEC’s historical database (except for pH - see previous section for criteria used).  Parameters with a score of 5 (coded as green) had values that did not exceed a state standard or were below the 75^th percentile of the records for that parameter in the historical database.