See _Idaho: the Whitewater State_ by G. Amaral (Watershed Books, 1990).
Lat / Longitude data are _very_ approximate.
Note: according to Amaral, the USGS renamed this river "Malad" in the 1970's. However, at USGS websites, both names seem to work.
At normal low flows, the upper section, above the first dam you come to, is short, .8 miles. But - its always runnable, with beautiful warm blue spring-fed water which is about 55 degrees year round. If you hike .2 miles past a locked gate, there is an official kayaker putin (below another dam); or you can putin elsewhere along the road. It starts easy and becomes quality class IV in the last 1/4 mile. A good line at the crux drop at low winter flows is to go right, like it looks, taking the drop with left boat angle to avoid the rock right below. You can hike a few laps on that section. At 1500, the upper section looked sustained, and the right side gets tougher, with piton rocks in the middle. A narrow boof through a rock slot opens up on the left. The dam is a mandatory portage left, with a large takeout eddy.
At high flows, the lower mile is popular with solid big water boaters. It ran over 2200 in spring 2012. Idaho locals still call it class IV, but "pretty continuous at 1300+". Put in below the first dam, that you can drive to (there is a staircase for kayakers) and take out at the Snake access parking lot.
Once you get accustomed to the dams and diversion canals all along this run, its quite a beautiful basalt-walled canyon. Some of the largest sagebrush I've ever seen is along the dirt road along this run; 7 foot tall sagebrush that give you an idea of what an "old growth sagebrush" ecosystem was like; a threatened, vanishing ecosystem that sage grouse, pygmy rabbits and others need for their survival.