The department has adequately characterized water chemistry on large and medium rivers using its fixed station network, run in cooperation with the U.S. Geological Survey. Smaller streams, which are both more numerous and often more susceptible to water quality problems due to a smaller volume of flow, are not as well defined. To help us better understand these smaller streams, department staff conduct chemical monitoring on numerous sites each year.

Some of these sites are in watersheds that are considered to be typical of regional land use and whose stream water quality is influenced only by these uses and not by a specific pollutant source. Data from these streams define “background” water quality within specific regions of the state.

Other sites are on streams impacted by existing, or threatened by future, pollution sources. Data from these sites have three types of uses:

  1. Comparison to established state water quality standards to determine if the stream meets these standards. If not, the can be classified as impaired and this data can then be used to develop Total Maximum Daily Loads.
  2. Comparison to regional “background” water quality to determine if water quality in the stream deviates from regional norms.
  3. Determine if there are any obvious trends in water quality.

Staff conduct field measurements for flow, water temperature, conductivity, pH and dissolved oxygen. Samples are collected and returned to the department's Environmental Services Program laboratory for a variety of chemical parameters including acidity, alkalinity, bicarbonate alkalinity, ammonia, chloride, nitrate, total nitrogen, total Kjeldahl nitrogen, phosphorus, sulfate, hardness and metals (calcium, cadmium, iron, lead, magnesium, manganese, nickel, potassium, sodium and zinc).