What is compensation water?

This is the quantity of water, generally referred to as the volumetric flow that must be discharged from an impounding reservoir. This is required to ensure that the natural river conditions downstream of the reservoir are maintained and that the rights of riparian owners, the flora and fauna and other parties who may abstract from the water course downstream of the reservoir are met.

It is important to ensure that the aquatic environments that rely on a consistent flow of water are managed responsibly. Large volume abstractions are therefore governed by regulators and as such a licence to abstract water must be applied for This ensures that the abstraction is limited thus allowing the good management of the environment downstream.

Some downstream aspects to consider are:

  • drying out of rivers and wetlands
  • variable flows of water below hydropower stations and water supply reservoirs may result in bare banks and stranded fish
  • low water levels in reservoirs can result in drying out of the shore line. This can prevent growth of plants and spawning fish
  • downstream sediment may be reduced in water bodies. This is required for fish and insect life and will change the ecological balance of the water course.
  • Reduction of downstream flow can mean that treated waste water discharge into the water course may not be as dilute as is required which in turn may affect water quality and aquatic life.