Environmental flow is the minimum supply that must be maintained in the watercourse so as not to affect the ecosystem downstream of a project that disrupts the flow of a river.
Key objectives:
a) the conservation of the river as a habitat for specific species
b) the preservation of the natural landscape
c) the minimization of the impact on downstream use (agriculture, etc.)
For example, for water intakes, the largest of the following quantities must be considered, unless its increase is documented due to the requirements of the downstream ecosystem (existence of a significant ecosystem):
• 30% of the average supply of the summer months June-July-August or
• 50% of the average supply for the month of September or
• 30 L/s (1.8 m3/min 108 m3/h) in each case.