While feasible, using lake/river water always sounds like a lot of
maintenance trouble to me. Everything in irrigation systems are
vulnerable to algae, silt, sand, rocks, snails, tadpoles, tiny fish, etc.
So you must use a good filter system before the pump intake so
it won't clog, then filter the pump output yet again using an even
finer mesh so the valves and spray heads won't clog. Even so, I
anticipate you will clean the screens and filters several times
each season.
My best advise is to speak with the folks at Sprinkler Warehouse.
They helped me DIY spray/drip my front yard and their prices are
hard to beat...
www.sprinklerwarehouse.com
An excellent resource for DIY irrigation is to read ALL of Jess Stryker's
tutorials. He's a landscape architect and an irrigation specialist with
lots of experience. His free web site has been around a long time.
Jess's advice will save you tons of money if you take the time to
read, understand, and follow his experience...
www.irrigationtutorials.com