Literature is reviewed in relation to particular Scottish problems. The individuality of water bodies and methods of harnessing available power necessitates individual treatment. Some general conclusions can, however, be drawn.
The creation of impoundments and the raising of lake levels are considered in terms of the effects on agriculture, rare plant and animal species, lake plankton production, introductions and the growth of fish.
The consequences of fluctuating lake levels are reviewed with reference to the productivity of shallow water communities, bottom animals and the growth and reproduction of fish.
Pollution, changes in temperature and chemical factors, and alterations in the volume and stability of rivers are considered.
Anadromous fish conservation measures include guarantee of minimum river flow, provision of freshets, construction of fish passes, erection of smolt screens, passage of smolts through turbines, creation of artificial spawning gravels, use of hatcheries and the opening up of previously unutilized natural spawning gravels.
In general, hydro-electric schemes have a depressing effect on biological productivity. This effect may be lessened through the application of gained knowledge and experience. Fundamental research into this branch of applied ecology is needed.