It's been 20 years since I fished that river, the river below the lake is accessible by logging roads, or was. There were lots of accessible spots, just need to do a bit of hiking to scout out runs. The river was unfortunately being logged extensively , right down to the banks at the time. The earliest I fished there was February and caught fish. More often in March even in to April. End of Feb in to March seemed the most productive. Most of those north island rivers seemed to be later runs. It might be a bit early right now but could be some fish. In those days double digit days were not uncommon, all C&R of course. Bigger river than the cluxewe keogh and Quatse, so if you hook one they have room to run. Good luck!