With all those falls, the water table around the Niobrara must be quite high and the ground very porous, rather like the island of Manhattan before it was sold to the Dutch West India Company by the Manhattan (and other) Indians. Manhattan is pocked with hundreds of natural springs, so many that it's estimated that if the relief pumps in the New York subway were turned off, the entire subway system would be flooded with spring water in one week. Luckily for the Niobrara, no pumps are necessary.
If you've ever wanted to make a difference but found it hard to believe that one person could... check out the Kiva Team Caedes discussion thread and discover that anything is possible.
-Nik