Biological aspects of water pollution and water supply problems

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Sanitary biology is the science having to do with the relationship of aquatic organisms to water supply, water pollution, and waste disposal problems. Although the fields oyerlap, it is distinct from sanitary bacteriology in that it generally deals with organisms higher than the bacteria. It is concerned with the influence of the environment on the organisms, such as the effects of pollution on fish, and with the influence of the organisms on the environment, such as the effects of algae on water supplies.
The relationship of algae to water supply and waste disposal processes is one of the most important phases of sanitary biology Algae frequently create nuisances in water supplies, the most serious of which is probably their effect on the palatability of the water. Increased use of water in a river basin may be accompanied by the development of algal problems The river may be enriched by the discharge of nutrients in the form of domestic sewage or other organic wastes from the cities and industries along its banks. Increased irrigation and other agricultural drainage may be a further source of nutrients, making the environment more favourable for the growth of plankton populations. The impounding of reservoirs creates areas with the slow current favourable to plankton; if silt turbidity is present. the slower current allows this to settle and there is greater light penetration for photosynthesis. As the plankton populations build up, they in turn can affect the environment, making 'the water unpalatable or difficult to treat for water supply purposes. Some of these changes may be taking place on the Waikato River, where taste and odour problems in water supplies have been associated with plankton blooms in the reservoirs impounded in recent years.