In our watershed, researchers have identified the upper reaches (headwaters) of tidal creeks as “sentinel habitats,” acting as first responders to the physical, chemical, and biological changes resulting from human activities. When impervious surface in these areas is 10 to 20% of total land area or below, the physical, chemical, and biological processes of a tidal creek function normally. However, when the impervious cover exceeds 20% these processes are damaged by the rapid influx of polluted runoff and water quality, habitat quality, and the abundance of aquatic organisms declines. In addition to ecological costs impervious land cover can increase flooding, beach and shellfish bed closures, and public health risks due to bacterial contamination. Learn  more about how human activity impacts the Charleston Harbor watershed.