Piping water into the Great Basin from other watersheds is not a
new idea, in fact we already do it.
Strawberry Reservoir exists so that water can be pumped through a tunnel from the Colorado River basin into the Great Basin. Most of this water is used for irrigation. In fact, most of the water use in the great basin is agricultural, not (as most people think) lawns. Lawns are not helping, but their not the main problem.
Bear Lake drains into the Bear River, which drains into the Great Salt Lake, so we already get all that water.
Getting water from the Snake River is an interesting thought. I would take it from the American Falls Reservoir and pump it up to Daniels, above Malad. From there water can flow into the Bear River and then into the Great Salt Lake. That distance measures 34 miles, which is an
easy distance to build a pipeline.
The thing is, it's not the pipe that is expensive. It is the power required to pump the water, which is incredibly heavy. For a proposed pipeline from the Missouri River into the Colorado basin, the expected energy requirements were somewhere in the order of several medium-sized
states worth of electricity consumption. Produced the conventional way, the greenhouse gasses produced by raising up so much water would offset any environmental good done by having the lake be full.
Now, in the not-so-far future when every rooftop has a solar panel and energy prices are essentially free, I can see this happening. But until then the best thing we can do is to conserve water.