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The criteria and values on this site are ambient water quality standards which apply to the surface waters in the State of Indiana. These are the concentration of substances which if not exceeded, should protect aquatic life, human health, and wildlife from adverse effects; either from short term exposure or long term exposure. These criteria and values were calculated using methodologies contained in Indiana's Water Quality Standards Rules for the Great Lakes Basin (Indiana's Water Rules are downloadable for more information). The water rules list the equations and methods used to develop Tier I Water Quality Criteria (standards which have been calculated using a complete data set) and Tier II Water Quality Values (standards calculated using less than a complete data set).
The Water Quality Standards on this site come in three forms:
Aquatic life criteria and values are divided into:
Human health criteria are further divided into:
Human health criteria and values are also divided into:
In the permitting process for point source dischargers (National Pollution Discharge and Elimination System permits), Water Quality Based Effluent Limits (WQBELs) (restrictions on the amounts of substances that can be discharged into surface waters of the state) are developed that ensure that point source discharges, such as a discharge from a waste water treatment plant or industry, will not cause an exceedance of the ambient water quality standards.
If you are having difficulty with terminology, visit U.S. EPA's Terms of Environment web site.