Waimea Plains water users, including urban users, will face stage one water restrictions from Monday.
The 20 per cent cuts do not include irrigators using the lower Confined and Hope Minor aquifers.
Tasman District Council's Dry Weather Taskforce convenor Dennis Bush-King said the river and groundwater levels had been dropping steadily.
He warned the rest of the district was experiencing similar conditions and without rain other catchments were likely to be subject to water restrictions in the coming weeks.
The Nelson City Council is also asking residents who take their water from streams or wells to use it responsibly and conserve it whenever possible. The restrictions do not apply to those on the council reticulated supply, and water levels in the Maitai Dam and Maitai and Roding rivers are adequate.
Next week's rationing in Tasman district will apply in the Upper Catchment, Reservoir, Waimea West, Delta, Golden Hills, and Upper Confined Aquifer zones on the Waimea Plains.
Some Golden Bay water users are also operating under restrictions based on conditions in their water permits.
Mr Bush-King said the council was aware some users may be tempted to increase their water use within allocation limits due to fears of further restrictions. "But this does little beyond exacerbating the drop in aquifer levels and further impacting river flow. By continuing to operate a careful use of water, as is currently being exhibited by most users, the need for more drastic measures can be delayed and hopefully averted."
Staff are continuing to monitor all key rivers, groundwater and salinity levels throughout the district, he said.
Mr Bush-King said that notices would be sent out to all water permit holders subject to the rationing direction this week.
The council will also issue a Conserve Water Notice in the urban areas of Richmond, Mapua, Ruby Bay, Brightwater, Hope, Wakefield, Tapawera and their rural extensions.
This also applies to the rural water supply schemes of Redwood Valley, 88 Valley, and Dovedale. Hand-held hosing only is permitted on odd and even calendar days corresponding to the house's street number.
Owners of private domestic wells in the areas subject to rationing are also directed to only water domestic gardens every second day.
Mr Bush-King said that anything people could do to conserve water through the rest of February and March would be good. While some rain is predicted for the end of next week it does not look to be substantial.
- The Nelson Mail
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