My teacher was roughly right about Lost River flowing out as springs along the Snake River Canyon to the south and west of where Lost River seeps into the Snake River Aquifer. There probably isn’t enough dye in the world to prove it, though. All the rivers in the ranges north of the Snake River Plain disappear into the aquifer, so adding dye to one of them would be a tiny drop in a big bucket.
There are two rivers that carry the name of the missing, Big Lost River and Little Lost River. Both disappear into the porous lava at Big Lost River Sinks, near Howe. It’s not as though they take a direct route from there, to say, Minnie Miller Springs. The Snake River Aquifer is huge, underlying some 10,800 square miles of southern Idaho, holding 200 to 300 million acre feet of water. That’s roughly the equivalent of Lake Erie.
The water does flow out of the walls of the canyon through the many springs in the Magic Valley. It also bubbles up from beneath the river itself, as in the case of Blue Heart Springs.
So, the rivers that carry the name aren’t really lost. We know where they went. Unfortunately, we are losing that invisible lake beneath the ground. The treasure of water that is the Snake River Aquifer has been mined to bring a million acres of desert to life through groundwater irrigation. Another two million acres are irrigated by canal, keeping water that would have recharged the aquifer from doing so. We’re taking more out of it than flows into it. The famous Thousand Springs, though still beautiful and productive, have been decreasing in flow for years.
Fortunately, efforts are currently underway to recharge the aquifer by sending water into the ground, in effect creating man-made lost rivers.
If you want to learn more, you can’t do better than to go to the Digital Atlas of Idaho. It’s a wonderful resource for students and adults who want to learn more about their state.