What have we learned?
The studies of stressed river systems have yielded some interesting knowledge. Some of this technology is summarized here:
Multiple Antibiotic Resistance: For example, how do we know whether bacteria in a river system comes from humans, livestock, or wildlife? This is an important question because bacteria can contaminate shellfish harvesting areas, and the most effective way to fight the contamination is to determine the source of the bacteria. The most practical and promising method for doing this is called Multiple Antibiotic Resistance.
Generally, human bacteria are very resistant to most antibiotic, bacteria from livestock are usually resistant to
antibiotics commonly used by veterinarians, and bacteria from wildlife are the least resistant. By using these observations, this technique, and its further refinements, scientists can pinpoint the source of a given bacteria problem and identify corrective actions.
Chlorophyll-a Monitoring: Although nutrients are essential for plant growth, high nutrient loads can cause excessive algae biomass. This is a problem because the high amounts of algae can cause problems with dissolved oxygen levels and cause fish kills. Chlorophyll-a measurements in estuarine and coastal areas can help identify nutrient sensitive areas. The effects of sewage plant discharges, stormwater inputs, and airborne deposition can be measured inexpensively with chlorophyll-a monitoring.
Improved Computer Modeling: Sophisticated water quality models are being developed to simulate the effects of tidal surface waters, wetlands areas, stormwater and point source inputs, temperature, flow rate, and other variables on water quality. These models can help determine where river systems can accommodate future growth and where additional controls are needed. Newer models can also link to geographic information system (GIS) data so that relationships between land use patterns and surface water quality can be illustrated.
Watershed Management
Using these techniques, watershed approaches are underway in both the Neuse basin and the Ashley & Cooper basins. In the Neuse basin, efforts are focused on reducing nitrogen inputs by 30% within 5 years. While in the Ashley and Cooper Rivers, which are both over 80% influenced by point sources, and the focus is on reducing industrial and municipal discharges of pollutants. In each case, the objective is to return the rivers to a healthy state by improving levels of dissolved oxygen and lower levels of pollutants.
A critical strategy in both cases is the development of a technically sound allocation method for waste loads to the river basins. As stated above, a final total maximum daily load (TMDL) standard has already been approved by the U.S. EPA for the Neuse basin. TMDLs can be considered a watershed budget for pollutants, representing the total amount of pollutants that can be assimilated by a stream without causing water quality standards to be exceeded.
Successfully addressing and correcting water quality problems in a watershed requires a comprehensive assessment of water quality and of water pollution sources. A phased approach, sometimes called a restoration plan, is used to identify sources of water quality impairment and to find corrective actions to reach the TMDLs and other goals and standards.
If your river basin is undergoing a basinwide planning process, you now know some of the key terms and issues that may be discussed. We encourage you to participate in the process and to express your views.
If you would like help with your NPDES Permit, Industrial Pretreatment Permit, Stormwater Permit, or related Plans and Services, please contact
OMNI at 800-951-7625 or visit our website at www.environmentalengineers.com |
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