What Do We Do?

The Storm Drain Detectives conduct six water quality tests each month to monitor the impact of storm drain run-off. The tests are:

Dissolved Oxygen

  • The amount of oxygen dissolved in the water is called D.O., or Dissolved Oxygen. 
  • D.O. is important because aquatic organisms need oxygen to survive and grow. Too much or too little D.O. can be dangerous to the river ecosystem. For example, for water to support cold water fish, such as trout or salmon, the D.O. level should not fall below 6.0 to 8.0 milligrams per liter.
  • D.O. levels can increase and decrease when dead organic matter, sewage, yard waste, and oil and grease enter the river.
  • D.O. data is collected using two different instruments, the CheMet kit, which samples water removed from river in sampling can, and the D.O. meter, which actually dangles a probe into the river to sample the ambient water. Only the D.O. meter’s probe data is posted on this website.

Water Temperature

  • This is a measure of the average kinetic energy of water molecules. The faster or slower water molecules move increases and decreases the temperature respectively.
  • Temperature is important because it affects water chemistry and functions of aquatic life. It influences the rate of plant photosynthesis, metabolic rates of organisms, sensitivity of organisms to waste and pollution, and the reproduction and migration of river animals, especially fish.
  • Temperature can change with the removal of vegetation around and in the river, soil erosion, storm water run off, and alterations to the river’s flow.
  • Water temperature is also measured using a digital probe. It is this information, taken from digital probes, that is posted on this website.

Electrical Conductivity/ Total Dissolved Solids

  • Total Dissolved Solids (TDS) is the amount of dissolved solids (i.e. salts) in the water. TDS can be measured indirectly by measuring the electrical conductivity. The more dissolved salts in the water, the more electricity the water will conduct.
  • Electrical conductivity (EC) is the ability of the water to conduct an electrical current.
  • Conductivity is important because it directly effects the quality of the water used for drinking and irrigation. Because conductivity measurements are based on the ionic composition of the water, many organisms can be hurt or helped by a small imbalance of these ions.
  • Conductivity will vary depending on the source of the water.
  • Conductivity will also vary with the source of run-off, whether it be rainfall, water drained from agricultural fields, or waste water drainage. This means conductivity can indicate ground water seepage or a sewage leak.
  • EC is measured three times, and the average result is recorded.


  • This is a measure of how acidic or basic the water is. These measurements identify the hydrogen ion concentration. This concentration is translated into a pH scale that ranges from 0 to 14 and reveals the hydrogen ion levels in the water. A pH level of 7 is neutral. A level between 0 and 7 is acidic, and a level between 7 and 14 is basic.
  • pH is important because many chemical reactions inside aquatic organisms depend on a very narrow, specific pH range. pH changes may also alter the concentrations of other substances in the water so they become toxic.
  • pH changes can come from the input of man-made and natural acidic or basic substances from run off that flows into the river.
  • The pH in the water collected from the river is tested using two different protocols. The first test is done using a pH test strip paper, followed by a second test with pH probe meter. Only the pH meter’s data is posted of this web-site.
  • pH is measured three times, and the average result is recorded. 


  • Turbidity is a measure of the amount of suspended particles in the water. Algae, suspended sediment, and organic matter in the water increase turbidity to unhealthy levels for certain organisms. It is an effective way to communicate the clarity of a given body of water. 
  • Turbidity is important because a high level of suspended particles in the river can diffuse sunlight and absorb heat, which increases temperature and reduces the light available for plants. High levels of suspended sediments can also clog fish gills and smother fish eggs.
  • Turbidity increases with bank erosion, excessive algal growth, changes in the river’s flow, and human activity such as boating or swimming. 
  • The Turbidity of a water body can be affected by runoff from local streets, generated by over-irrigating, rainfall, and construction activities.  

Nitrates (NO-3)

  • Nitrogen is an element needed by all plants and animals to build protein. In aquatic ecosystems, nitrogen is naturally present in many forms.
  • Urban and farming run-off to the river can significantly increase nitrates levels in the water. Sewage can also be a source of nitrates if added by humans to the river. Nitrates can be an indication of high levels of fertilizers, animal waste, or other run-off contamination.
  • A nitrate test strip is used.

Additional Information

For references on information in this page see the Acknowledgements, references 1 to 4. View images of the testing tools used by the Storm Drain Detectives.