if you've got internet access the Otago Regional Council have a page with close to real time data on river flows and rainfall at certain locations.
http://water.orc.govt.nz/WaterInfo/Default.aspxbeats having head down to the river to look.
its also helpful to use after heading out. good to use as a reference point. if i dig a good hole at the edge of the river and have any water issues for example, i can hang out at home for it to go lower, then head back at some point and dig lower.