I irrigate out of a creek in KS . We have just used a screen on the end of our suction pip[e have about a 7ft lift from the creek level to the pump level . about 3ft of water depth where the suction pipe goes in the water .It has worked fine compared to a river screen. You can plan on having high water or aflood at least once a year and I would rather not have my $5000 river screen washed away.  You can always do some dirt work and make  you a pumping site at the corect level to the water level  15ft make it hard to prime and is inefficient. My dad put in this system in 1979 with a quarter mile pivot still works fine  only 1 year with out water, If you pump out of a creek be prepared to go rescue the pump in case of big rain. You can fix a lot of the terrain issues and water depth issues with  a backhoe