Tidal Creeks - Coastal Development

Our coast lines are alluring places for millions of people, residents and visitors. In fact, 50% of the US population lives in coastal counties, which account for less than 20% of the nation's land area. Local watersheds have been developing faster than the population has grown. For example, Charleston's urban area increased by 250% from 1970 to 1990s while the human population only increased by 40%. This type of development is called urban sprawl.

Coastal development can have negative impacts on the environmental quality of tidal creeks as well as ultimately impacting the quality of our coastal living. Large amounts of impervious cover – roofs, roads, parking lots – in the watershed can be a threat to the health of our creeks and salt marshes. The amount, timing and quality of stormwater runoff from this type of rapid watershed development carries sediments, chemicals, bacteria, virus', nutrients and other pollutants into tidal creeks and salt marshes. These pollutants come from many hard to identify sources, sometimes called non-point source pollution. They degrade the water quality of the receiving waterbodies, primarily tidal creeks in the coastal southeast. Chemicals also accumulate in sediments to levels that can harm marine life. Swimming in creeks with degraded water quality or eating fish and shellfish from degraded creeks may adversely affect public health.

A framework and conceptual model for understanding the changes in ecological and public health indicators based on impervious surfaces associated with coastal development was developed. When the amount of impervious cover in the watershed of these systems exceeds 10-20%, water and sediment quality were impaired. Impairment of living resources and nursery functions were generally detected when the amount of impervious cover exceeded about 20-30% of the watershed area.