Water restrictions are in place in the Tasman district, as parts of the South Island face up to the prospect of a continued dry-spell.

Forecast rain isn't expected to be enough to ease demand, and low river levels are prompting concern.

Tasman District Council's Dennis Bush-King says the restrictions will impact around 500 permit-holders all together.

"It basically affects the Waimea Plains and the Motupiko area and there are some other smaller attachments like the Riwaka and the Moutere."