We do the property maintenance for a new HOA. The current contractor, a housing developer, has had a heck of a problem with small clams getting into the main line and messing up the valves (irrigation water fed from a subdivision pond). They claim to have to dismantle and clean out at least 2 or 3 valves per day. My problem is: We will be assuming maintenance of the irrigation upon the developers conclusion of responsibilities to the subdivision. Anybody have any thoughts on how to fix the problem?