Boise River in town

Heavy rain in the Middle Fork and South Fork Boise River drainages washed large amounts of sediment into the rivers.  Both systems drain into Arrowrock Reservoir - which is drawn down and discharging the sediment-laden water into Lucky Peak Reservoir. Here's where it gets interesting.  In the summer the water in Lucky Peak Reservoir stratifies with the warm water on the top of the reservoir and colder water on the bottom.  The sediment layer from Arrowrock Reservoir is moving along the bottom of the reservoir, and because the Lucky Peak Dam discharge takes water from the bottom of the reservoir, it's picking up the sediment laden water and passing it down the Boise River. Within the next 6 - 8 weeks, we expect Lucky Peak Reservoir to "turn-over."  When this happens, all the different temperature layers of water in the reservoir will mix and water passing from Lucky Peak Dam into the Boise River should clear. I've been with IDFG for 30+ years and lived in Idaho for over 50 years.  This is the longest I can remember the Boise River running muddy in the middle of the summer.