Changes are planned to a scheme which releases supplies from reservoirs into watercourses in the Worth Valley.
Notice has been given of proposed alterations by Yorkshire Water (YW) of the amounts which can be shifted until 2017.
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 that 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.”