River Water Analysis

Monitoring and analyzing river water quality is essential for ensuring the quality of drinking water and protecting human health, wildlife, and recreational fisheries. Monitoring programs may also be used to evaluate and correct water-quality issues--such as impacts on fishing because of seasonally reduced water quality. River water quality can be affected by any activities in the watershed--i.e., the entire area that supplies water to the river through runoff or groundwater flow.

Dissolved Oxygen

• Dissolved oxygen levels in a river can be reduced by algal blooms--these are usually the result of increased nutrients. Fertilizers used in agriculture (or even in residential areas) can enter the water supply through surface runoff, causing an overgrowth of plants and algae and a reduction in dissolved oxygen. Dissolved oxygen is critical to the survival of aquatic wildlife, especially fish. In some areas, only non-native fishes are able to thrive in low oxygen environments. Poor water quality can promote the spread of invasive species. Dissolved oxygen must be constantly monitored with a probe.

pH

• The amount of free hydrogen in comparison to hydroxyl ions in the water determines the pH of the water--how acidic or basic it is. Different chemicals in the water can affect pH, which in turn greatly affects the health and survival of aquatic plants and wildlife. Acidity (low pH) can also give drinking water a bitter taste. Like dissolved oxygen, the pH levels of river water must also be monitored constantly by a probe.

Turbidity

• Turbidity is essentially a measure of how "murky" the water is. Plants and fish do not thrive in very murky water with high turbidity. Turbidity can be measured using a Secchi disk. The disk is lowered into the water until its black-and-white contrasting sections are no longer distinguishable. More often, turbidity of collected water samples is evaluated using a turbidimeter in a lab.

Chlorophyll

• High levels of chlorophyll in river water indicate high nutrient levels (from fertilizer runoff) and high levels of algal growth. Chlorophyll levels are determined by fluorescence spectophotometry analysis of collected water samples.

Nutrients

• Nutrient levels in river water must be monitored continuously because maximum levels have been set by the U.S. Environmental Protection Agency (EPA). Nitrates and phosphates enter the water as fertilizer runoff, influence water quality, and can drastically change the composition of plant and animal communities. Nutrient levels are measured using spectrophotometry of collected water samples.

Chemical Contaminants

• Various chemical contaminants must also be monitored and are regulated by the EPA. Studies have shown that most creeks and rivers contain a "cocktail" of insecticides, herbicides, and other pesticides. These chemicals can be dangerous to human health at high levels and have devastating impacts on wildlife, particularly amphibians such as frogs. Chemical contaminant levels are usually also associated with agricultural activity in the watershed.