Protecting Public Health and the Environment.
Numeric criteria are required where necessary to protect designated uses. Individual numeric criteria are based on specific data and scientific assessment of adverse effects. Numeric guidelines assign numbers that represent limits and/or ranges of chemical concentrations, like oxygen, or physical conditions, like water temperature.
A typical numeric statement for an aquatic life criterion usually contains a concentration and averaging period (acute – short term or chronic – long term). For example, for toxics, a one-hour averaging period applies for an acute (short-term) concentration, while a four-day average applies for a chronic (long-term) concentration. The criteria are values that should rarely be exceeded if uses are to be supported.
Idaho has numeric criteria for temperature, dissolved oxygen, pH, turbidity, bacteria, ammonia, and a list of 121 toxic substances (both metals [including mercury] and humanmade organic chemicals). The criteria values and the applicability of the criteria to a specific water body depend upon the designated use of the water.
Water Quality Standards CoordinatorDon EssigDEQ State Office1410 N. HiltonBoise, ID 83706(208) email@example.com
Common Water Quality MeasuresCriteria for Toxic SubstancesTemperature