The methods used in this experiment to evaluate the relationship between biodiversity and locations on the Red Cedar River were testing pH, dissolved oxygen, temperature, and hardness. pH is a measurement of the concentration of hydrogen ions in a solution, and determines the type of plants and organisms that can survive in and around the river. Typically, as the amount of rainfall in an area increases, the pH decreases and as the amount of rainfall decreases, the pH increases. As the amount of precipitation increases, the amount of nutrients in the river and surrounding soil decreases. Nutrients can include calcium and magnesium ions, which relate to hardness of water. The higher the concentration of calcium and magnesium, the harder the water