Nelson MP Nick Smith is calling on the city council to reduce the amount of water it takes from the Roding River to help remedy the water shortage in the Waimea Plains.
The region's horticulture sector is struggling due to a lack of rain in recent months and is close to being in drought conditions.
Dr Smith said Nelson City Council can either access the town water supply from the Roding River or the Maitai Dam, and he said the latter should be chosen as the Roding River flows into the Lee, which then flows into the Waimea system.
He said every litre taken from the Roding is a litre less that can be used for maintaining the horticulture industries on the Waimea Plains.
But Nelson mayor Rachel Reese said the council was currently not taking any water from the Roding River, and relied solely on the Maitai Dam and the Maitai River.
She said the council was committed to a regional water approach, especially in times of limited water.