Water pollution  is any contamination of water that lessens its value to humans and other species, aquatic and non aquatic

Point source water pollution is when there is a defined location that is discharging the waste such as a pipe

Non point source pollution does not have a specific location of discharge, instead it can come from places such as farm lands

Sediment pollution are inorganic soil particles such as sand that are eroded from soils and washed from roadways. Sediment pollution comes from erosion from natural sources or from human activity. The sediment may carry harmful pollutants into the water and also clog areas of the water that may be used as a breeding ground for fish.

Inorganic Nutrient Pollution are nitrates and phosphates which are nutrients to plants, especially aquatic plants. Nitrates and phosphates come from agricultural fertilizers, domestic sewage and livestock wastes.There is natual eutrophication causing nutrient enrichment but excessive release  of nutrients can cause accelerated eutrophication.

Thermal pollution is an increase in temperature of the water that adversely effects organisms living in it. Thermal pollution can come from electrical generating plants. Thermal pollution can cause reduction in dissolved oxygen, interference with reproduction, increased vulnerability to disease, direct mortality, invasion of destructive organisms, undesirable changes in algal populations, destruction of organisms in cooling water

Water contaminated with infectious microorganisms is the most common environmental factor to cause human illness. Human illness include cholera, typhoid fever, dysentery, polio and infectious hepatitis. These diseases are contracted when humans drink swim in or bathe in the waters. Pfiesteria is a microorganism causing problems in recent years. One organism can cause open sores and massive fish kills.

Heavy Metal Pollution are highly toxic elements such as lead and mercury that come from a variety of sources such as active and inactive mines. Metals may be washed into surface waters during heavy rains.They may also be washed from the sky during percipitation. Lead may also come from old pipes in houses built before 1930. Lead poisoning may occur causing decreased learning ability, convulsions, death and stunted growth. Mercury in water ways come from industrial discharges and also from rain and snow. The rain and snow can pick up pollutants from coal fired power plants or incinerators that burn garbage. Mercury is also being found in many fish in Michigan. Mercury may reduce conginitic ability. The birds that are eating fish contaminated with mercury has reduced reproductive success and growth.

Oxygen-Demanding Organic Wastes are wastes that consume the excess oxygen in the water and leave nothing for other animals, causing asphyxiation.

Hormone disruptors are chemical pollutants that alter the hormonal system of animals that ingest them, affecting reproduction and other vital functions in humans and wildlife. Dioxin is a hormone disruptor which can come from paper mills. Also, femal sex hormones derived from birth control pills show up in the water excreted from womens urine. This chemical can cause a shift in gender of male fish. Prescription and non prescription drugs are showing up in water ways from human urine being released from sewage treatment plants, these chemicals can kill tiny crustaceans.

Plastic pollution can cause wildlife mortality by: after being swallowed it can not be difested or voided so there is a block in the digestive track causing death, plastic entanglement may cause drowning or starvation by preventing birds and mammals from searching for food.

Oil pollution can cause death to many animals. Also, hydrocarbons in crude oil mimc chemicals used by marine animals to guide them during mating, feeding, homing and migrating. The psuedosignals from the oil will alter the behavior. Also, oil has carcinogens in it and when the oil is ingested through the water or fish by humans, it can have an impact on the human.

Air pollution can have an effect when airborne hydrocarbons released from factories, service stations and vehicles rain down into the water way