Changes are planned to a scheme that releases supplies from reservoirs into Worth Valley watercourses.
Notice has been given of proposed alterations by Yorkshire Water (YW) of the amounts that can be shifted.
The system enables water to be moved during prolonged dry spells to balance YW’s requirements with environmental needs.
A YW spokesman said: “We are proposing to alter the amount of water we release from our reservoirs into the rivers.
“We make such releases – called compensation releases – to make up for the fact we store water in our reservoirs.
“The proposal involves altering the amount of water we release from Leeming and Leeshaw reservoirs, and from Ponden and Lower Laithe reservoirs, to Springhead Weir if we experience a dry year.
“The flows have been designed to satisfy both the needs of the environment and those of Yorkshire Water to maintain public drinking water supplies into the future.”
The existing system has been running since March 2010 and, if approved by the Environment Agency, changes will remain in place until 2017.