The Basics of Water Quality and Estuarine Ecosystems
Water quality assessment starts with compliance to water quality standards. States and other jurisdictions adopt water quality standards for their waters. EPA must then approve these standards before they become effective under the Clean Water Act (EPA 2010). It is important to remember that we all use and consume water and therefore standards ensure that we maintain clean drinking water and waterbodies.
Water quality standards have three elements: the designated uses assigned to waters (e.g., swimming, the protection and propagation of aquatic life, drinking), the criteria or thresholds that protect fish and humans from exposure to levels of pollution that may cause adverse effects, and the anti-degradation policy intended to prevent waters from deteriorating from their current condition. After setting standards, states assess their waters to determine the degree to which these standards are being met. To monitor water quality, states may take biological, chemical, and physical measures of their waters; sample fish tissue and sediments; and evaluate land use data, predictive models, and surveys (EPA 2010).
Estuarine Water Quality and Dynamics
An estuary is a partially enclosed body of water along the coast where freshwater from rivers and streams meets and mixes with salt water from the ocean. Estuaries and the lands surrounding them are places of transition from land to sea and freshwater to salt water. Although influenced by the tides, they are protected from the full force of ocean waves, winds, and storms by such land forms as barrier islands or peninsulas (EPA 2010).
Estuarine environments, such as we have in coastal South Carolina, are among the most productive on earth, creating more organic matter each year than comparably-sized areas of forest, grassland, or agricultural land. The tidal, sheltered waters of estuaries also support unique communities of plants and animals especially adapted for life at the margin of the sea (EPA 2010).
Importance of Estuaries:
Estuaries provide us with a suite of resources, benefits, and services. Some of these can be measured in dollars and cents, others cannot. Estuaries provide places for recreational activities, scientific study, and beautiful viewsheds. Estuaries are an irreplaceable natural resource that must be managed carefully for the mutual benefit of all who enjoy and depend upon them (EPA 2010).
Thousands of species of birds, mammals, fish, and other wildlife depend on estuarine habitats as places to live, feed, and reproduce. Many marine organisms, including most commercially-important species of fish and invertebrates (e.g., shrimp), depend on estuaries at some point during their development. Due to their biologically productivity, estuaries provide ideal areas for migratory birds to rest and re-fuel, and breed. South Carolina has several small islands designated by the state as seabird sanctuaries in order to reduce disturbances during breeding season. Since many species of fish and wildlife rely on the sheltered waters of estuaries as protected spawning grounds, estuaries are often called the "nurseries of the sea." (EPA 2010)
The economy of many coastal areas, including coastal South Carolina, is based primarily on the natural beauty (tourism) and fisheries tied to estuaries. When those natural resources are imperiled, so too are the livelihoods of those who live and work in estuarine watersheds. Over half the U.S. population lives in coastal areas, including along the shores of estuaries. Coastal watershed counties provided 69 million jobs and contributed $7.9 trillion to the Gross Domestic Product in 2007 (National Ocean Economics Program, 2009).
South Carolina Water Quality and Monitoring
Water quality variables measured within South Carolina waterbodies are pH, conductivity, salinity, temperature, dissolved oxygen (DO), turbidity, fecal coliform bacteria, nitrogen, phosphorus, and biological and chemical oxygen demand (SCDHEC). These variables act as indicators of the health of the ecosystem. There are many reasons why portions of an ecosystem may become impaired as everything is intertwined and both abiotic and biotic fluctuations, or upstream anthropogenic activities can alter an ecosystem. As consumers within the ecosystem, we must also make sure to use sustainable practices as to maintain the balance within the system. Proper pesticide usage is one factor people can control and contribute to the overall health of the ecosystem and all of its inhabitants.
Pathogens were the largest cause of impairments in South Carolina's bays and estuaries in 2010, with approximately 166 square miles of bays and estuaries declared impaired. According to a 2005 EPA National Coastal Condition Report (EPA-620/R-03-002), the overall condition of U.S. coastal waters is fair, but 28 percent of coastal waters are not suitable for aquatic life and 22 percent are not suitable for human use (such as fishing or swimming). Proper monitoring and modeling by regulatory agencies (SCDHEC) and conscious efforts by residents and businesses can play a role in ensuring closures and impairments are minimized.
Fish can act as a good indicator for bioaccumulation and bioconcentration of pollutants in the water. We also consume fish in our diet, meaning better water quality is better quality fishes. Below is a map of fish consumption advisories (based on pollutant) issued by SCDHEC.
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