If creek water is too acidic or too basic, biochemical processes may be disrupted harming or killing plants and animals. Human activities influence the pH of our creeks. Air pollution from acid rain is a good example of what can happen when creeks become too acidic. As pH increases, smaller amounts of ammonia are needed to reach toxic levels for fish. As pH decreases, the concentration of metals may increase.
Higher acidity increases their ability to be dissolved from sediments.
In addition to the five parameters already discussed, schools measured water depth. Friends of Corte Madera Creek Watershed interpreted the data with much input from Mike Rugg at the California Department of Fish and Game. The number of graphs were kept to a minimum, because Friends thought it would be easier to make comparisons between parameters. However, it should be noted that plotting all or a number of parameters on a single graph, having a broad scale, tends to obscure any potentially significant changes in water quality. Changes in receiving water pH, for example, with an acceptable range of 6.5 to 8.5, are hard to discern, or not well represented on a scale of 0-25.