The Nelson Tasman Civil Defence is hoping floodwaters will recede today to unlock isolated areas

Multiple parts of the South Island were cut off in heavy rains yesterday, including Picton and Westport.

But in the Nelson Tasman area, State Highways into the region closed, leaving Nelson isolated, along with Takaka, Collingwood, and Murchison.

Local Civil Defence group controller Dennis Bush-King says they'll be looking at water levels this morning.

He says there's also an issue in the Motueka Valley that workers will be going to.

Bush-King says there's about 15 households on the other side ... and they can currently only walk across, but not drive.