With the Idaho General Trout Season Opener approaching, people are wondering when the Boise River System will be fishable. The Boise River Reservoirs (Lucky Peak, Arrowrock and Anderson Ranch) are managed primarily for irrigation and their objective is to capture the maximum amount of water in the reservoirs. They release water from the reservoirs as needed to capture the runoff and have “rule curves” they use to manage reservoir outflows. Looking at the Bureau of Reclamation Hydromet site you can see that the reservoirs typically reach their peak levels the 3rd or 4th week of June. This means the river flows below Lucky Peak and Anderson typically drop to their normal summer levels around that same time—a bit later on high water years.

Our Boise Tailwater rivers tend to come into shape quicker than the Freestone sections because of how they are managed. While the MF of the Boise will continue to run high well into July the SF of the Boise below Anderson Ranch and the Main Boise River below Lucky Peak will drop into shape quicker.

Here is a look at this year’s runoff flows on the South Fork, Middle Fork and Lower Boise Rivers compared to similar years of 2011 and 2019. Based on those years, the SF Boise will be running very high when the season opens and won’t drop to normal summer levels until early July. In 2011 and 2019 the Main Boise river dropped to normal summer flows by early July. This year we had more space in the reservoirs so it is possible that flows on the Lower Boise will stabilize a bit sooner in late June.

The rivers are running high and cold and are dangerous to wade. Do not attempt to wade the SF of the Boise River until flows drop below 600cfs this Fall. Same goes for the Boise in town. Make sure you check BVFF’s Local Waters page for the latest conditions, including streamflows, water temperature and reservoir/boat ramp levels.