Natural Hazards
A commmon example of a natural hazard is aquatic life and its by-products. Surface water can pick up nutrients like nitrogen and phosphorus from agricultural runoff. Add sunlight and you have the ideal environment for aquatic plants and animals to grow.
For example, blue-green algae, common to shallow lakes and dugouts, grows rapidly in warm nutrient-rich water and produces a toxin hazardous to humans, wildlife, and domestic animals.
Wildlife, farm animals, and pets need water and drink it directly from the source. If an animal is sick or has parasites, it is likely that it will contaminate the water as it drinks. Other animals may, in turn, drink the contaminated water and become infected.
The harmful organisms or pathogens left behind in the water can be in the form of bacteria, viruses, or protozoa such as Giardia and Cryptosporidium.
Human Hazards
As water is used for recreation, there is a possibility for contamination by:
- road runoff
- gas and oil from outboard engines
In addition, many communities discharge treated municipal waste into surface water, which affects downstream habitation.
Another hazard is runoff from heavy rain which contains hazardous chemicals from:
- agricultural property (pesticides and fertilizer)
- industrial property
Almost everything that goes into a storm drain will end up in a stream or lake. Most household or industrial chemicals are not removed by typical municipal treatment.
As surface water runs across the surface of the ground and is open to the atmosphere, it can pick up contaminants easily. Surface water should not be used without boiling or treatment.
Campers, hikers, or hunters who drink from a freshwater stream assuming that it is pristine, can get severe stomach cramps and persistent diarrhea that may last for weeks if untreated.
Contaminants can come from human activities such as camping or boating, which can leave gasoline and oil in surface water. Or contaminants can occur naturally as microorganisms, which are harmful to our health.
Surface water can contain many types of biological hazards, and it’s expensive to test for each type. Common tests are for coliforms or E. coli bacteria. The tests are simple, relatively inexpensive, and, if these indicator bacteria are detected, it’s a sign that other hazards may be present.
Chemicals can also contaminate surface water through runoff and upstream discharges.