River Length FlowsInto Clarence 209 Pacific Conway 48 Pacific Waiau 169 Pacific Hurunui 138 Pacific Waipara 64 Pacific Ashley 97 Pacific Waimakariri 161 Pacific Selwyn 95 Pacific Rakaia 145 Pacific Ashburton 90 Pacific Rangitata 121 Pacific Ophi 80 Pacific Pareora 56 Pacific Waihao 64 Pacific Waitaki 209 Pacific Kakanui 64 Pacific Shag 72 Pacific Taieri 288 Pacific Clutha 322 Pacific Hollyford 76 Tasman Cascade 64 Tasman Arawhata 68 Tasman Haast 64 Tasman Karangarua 37 Tasman Cook 32 Tasman Waiho 32 Tasman Whataroa 51 Tasman Wanganui 56 Tasman Waitaha 40 Tasman Hokitika 64 Tasman Arahura 56 Tasman Taramakau 80 Tasman Grey 121 Tasman Buller 177 Tasman Mokihinui 56 Tasman Karamea 80 Tasman Heaphy 35 Tasman Aorere 72 Tasman Takaka 72 Tasman Motueka 108 Tasman Waimea 48 Tasman