One of the most important variables to the overall aquatic health of a waterbody is its water quality. We monitor the physical and chemical properties of water to determine whether the water is of sufficient quality to support its beneficial uses, such as fishing and swimming. Anything dissolved in water, and much of the fine particulate matter suspended in water, is considered part of the chemical habitat of an aquatic organism. Just as organisms have a preferred physical habitat, they also have a preferred chemical habitat. Standard tests done include:

• Temperature (ˇCelcius)
• Specific Conductance (ˇseimen)
• pH (standard units)
• Dissolved Oxygen (mg/l)
• Instantaneous Discharge (cuft/sec)
• Alkalinity (mg/l)
• Turbidity (Nephelometric Turbidity Units)
• Total Kjeldahl Nitrogen (mg/l)
• Ammonia (mg/l)
• Nitrate (mg/l)
• Nitrite (mg/l)
• ortho-Phosphorus (mg/l)
• Total Phosphorus (mg/l)
• Total Hardness (mg/l)
• Sulfate (mg/l)
• Chloride (mg/l)
• Total Suspended Solids (mg/l)
• Total Dissolved Solids (mg/)

Additional parameters might include concentrations of various heavy metals, pesticides, fecal bacteria, or other organic compounds. These measurements are generally collected at least once a month to characterize a stream’s overall water quality. These concentrations are compared to Water Quality Standards using a standardized protocol described in Oklahoma’s Use Support Assessment Protocols to evaluate the water quality of the waterbody in question.

Stream water quality is assessed in conjunction with stream habitat and stream aquatic communities to determine the stream’s overall health.