The parameters for measuring stream health are summarized below. This provides information about how the specific water quality indicators of the Mississippi Headwaters River Watch Project describe river health. This information is excerpted from Mark Mit chell and William Stapp's, "Field Manual for Water Quality Monitoring," (second edition) Dexter, MI: Thomson-Shore Printers: 1986.

DISSOLVED OXYGEN (DO):
Dissolved oxygen is an essential element for the maintenance of healthy lakes and rivers. Most aquatic plants and animals need a certain amount of oxygen dissolved in water for survival. Some aquatic organisms such as pike and trout require medium to high levels of dissolved oxygen to live. Waters of consistently high dissolved oxygen are usually considered healthy and stable aquatic ecosystems capable of supporting many different kinds of aquatic organisms. The atmosphere, algae and vascular aquatic plan ts are the sources of dissolved oxygen in lakes and rivers; the accumulation of organic wastes depletes dissolved oxygen.

FECAL COLIFORM:
Fecal coliform bacteria are derived from the feces of humans and other warm-blooded animals. These organisms enter rivers through direct discharge from mammals and birds; from agricultural and storm runoff containing mammal and bird wastes; and from sewag e discharge. Even though fecal coliform bacteria are not pathogenic, they occur along with pathogenic organisms; therefore, their presence suggest the occurrence of disease-causing organisms. When fecal coliform counts are greater than 200 colonies/100 ml of water sample there is a greater chance that the disease-causing organisms are present. It is advised that water contact be avoided at this coliform level. Possible diseases and illnesses carried by such waters are typhoid fever, hepatitis, gastroenteritis, dysentery, swimmers itch, and ear infections.

pH:
The pH value of water, on a scale of 0 to 14, measures the concentration of hydrogen ions. Pure distilled water is considered neutral, with a pH reading of 7. Water is basic if the pH is greater than 7; water with pH of less than 7 is considered acid. For every one unit change in pH there is approximately a ten-fold change in how acidic or basic the sample is. Most valuable species, such as brook trout, are sensitive to changes in pH; immature stages of aquatic insects and immature fish are extremely sensitive to low pH values. Very acidic lakes and streams cause leaching of heavy metals into the water.

CARBONACEOUS BIOCHEMICAL OXYGEN DEMAND (CBOD):
Carbonaceous biochemical oxygen demand measures the amount of organic material in the water. Organic material is fed upon by aerobic bacteria which require oxygen. In this process, organic matter is broken down and oxidized. Protozoa prey upon the growing population of bacteria and also require oxygen. CBOD is a measure of the quantity of oxygen used by these microorganisms in the aerobic oxidation of organic matter.

TEMPERATURE:
Many of the physical, biological and chemical characteristics of surface water are dependent on temperature. Temperature affects the solubility of oxygen in water; the rate of photosynthesis by algae and larger aquatic plants; the metabolic rates of aquat ic organisms and the sensitivity of organisms to toxic wastes, parasites and diseases.

CONDUCTIVITY:
Conductivity measures the electrical conductants in the water. This is an indication of the quantity of dissolved inorganic acids, bases and salts in the water.

TOTAL PHOSPHORUS (TP):
Total phosphorus includes organic phosphorus and inorganic phosphate. Organic phosphorus is a part of living plants and animals. It is attached to particulate organic matter composed of once-living plants and animals. Inorganic phosphates comprise the ion s of bonded to soil particles and phosphates present in laundry detergents. Phosphorus is an essential element for life; it is a plant nutrient needed for growth and a fundamental element in metabolic reactions of plants and animals. In northern Minnesota, phosphorus functions as a "growth-limiting" factor because it is usually p resent in very low concentrations. This scarcity of phosphorus is attributed to its relationship with organic matter and soil particles. Any unattached or "free" phosphorus, in the form of inorganic phosphates, is rapidly taken up by algae and larger aqua tic plants. Because algae only require small amounts of phosphorus to live, excess phosphors causes extensive algal growth called algal blooms. Algal blooms color the water a pea-soup green and are a classic symptom of cultural eutrophication. Sources of phosphorus are human wastes, animal wastes, industrial wastes, and human disturbance of the land and its vegetation.

NITRATES:
Nitrate and nitrite are inorganic forms of nitrogen in the aquatic environment. Nitrate along with ammonia are the forms of nitrogen used by plants. Nitrates and nitrites are formed through the oxidation of ammonia by nitrifying bacteria, a process known as nitrification. In turn they are converted to other nitrogen forms by denitrification and plant uptake. Nitrogen, in its various forms is usually more abundant than phosphorus in the aquatic environment; therefore, nitrogen rarely limits plant growth as does phosphorus. Aquatic plants are not usually as sensitive to increases in ammonia and nitrate levels. Sources of nitrates are the atmosphere, inadequately treated wastewater from sewage treatment plants, agricultural runoff, storm drains, and poorly f unctioning septic systems.

TURBIDITY:
Turbidity is the relative clarity of water. It is the result of suspended solids in the water that reduce the transmission of light. Suspended solids are varied, ranging from clay, silt and plankton to industrial wastes and sewage. When turbidity is high, water loses its ability to support a diversity of aquatic organisms. Oxygen levels decrease in turbid water as they become warmer as the result of heat absorption from the sunlight by the suspended particles and with decreased light penetration resulting in decreased photosynthesis. Suspended solids can clog fish gills, reduce growth rates and disease resistance, and prevent egg and larval development. Settled particles can accumulate and smother fish eggs and aquatic insects on the river bottom, suffocate newly-hatched insect larvae and make river bottom microhabitats unsuitable for mayfly nymphs, stonefly nymphs, caddisfly larvae and other aquatic insects.

BENTHIC MACROINVERTEBRATES:
Benthic macroinvertebrates are bottom dwelling organisms that live in, crawl on or attach themselves to the river bottom. These are visible with the naked eye. Macroinvertebrates are good indicators of river health because they are sensitive to pollution, they live in the water over a year, cannot easily escape pollution as a fish can, and can easily be collected.