Water Quality Criteria

There are five major categories of parameters that are monitored or examined by Ohio EPA to evaluate the quality of surface waters.

  1. Inorganic chemicals – These include metals such as iron, calcium, magnesium and nutrients such as nitrates and phosphates. Iron, calcium, and magnesium are responsible for hard water and are primarily of natural origin. While many nutrients originate from photosynthesis and plant material decay, fertilizers and animal/ human waste can contribute excessive nutrients that can create algae growth and algal blooms that fouls waterways and stress certain species. Some trace metals can be quite toxic and are often related to urban and industrial activities.
  2. Organic chemicals – These include a wide range of carbon containing compounds. Many of these originate from natural sources such as decaying plant material; however, many are synthetic and related to human activities. These include nonvolatile to highly volatile compounds, such as PCBs, pesticides, industrial products, solvents, and gasoline components.
  3. Radiological chemicals – These include radon, tritium, and other radioactive constituents and are not an issue of concern except near nuclear facilities or mining areas.
  4. Biological populations – The biology of a waterway ranges from microscopic life, such as viruses, bacteria and protozoa, to larger macrofauna, such as insects, bivalves (mussels), fish, amphibians (frogs, salamanders), reptiles (turtles, snakes) and surrounding wildlife (ducks, geese, fish-eating birds, raccoons, mink, beaver). Typically, insects living on the bottom of a stream (benthic macroinvertebrates) and fish are the 2 populations that are monitored to determine water quality. To address human health concerns, the presence of microbial pathogens are monitored by measuring fecal coliforms and/or E. coli bacteria, which are indicators of human or other animal waste.
  5. Habitat conditions - A stream or river cannot have a good community, such as fish, without also having good aquatic habitat. Aquatic organisms need places to hide, feed, and reproduce. Typically, the most desirable species, such as the small-mouth bass and trout need both clean waters and good habitat. Good habitats consist of many factors including:
    • Coarse stream bottoms consisting of sand, gravel, and cobbles with smaller amounts of clay and silt.
    • Combinations of deep pool and shallow riffle areas that allow for different species that require slow or fast water conditions.
    • Tree limbs, boulders and debris piles that provide places for creatures to hide, spawn, and forage for food.
    • Stream banks covered with vegetation that prevent erosion and provide food.