I recently designed and installed an irrigation system on nearly 3/4 of an acre. We live in the Ozarks and the lawn slopes downhill at what is considered around here "a mild grade". The limestone bedrock is very close to the surface in many areas of the yard. I followed all the guidelines I could find on designing the system, and for the most part, I am thrilled with the results. However, I have one problem area. One section of the yard is a large ovoid with the narrow end surrounded by a driveway on both sides. This is at the bottom of the slope and water naturally drains to the area. I planted a "rain garden" (feet wet plants) at the bottom even before the irrigation system was contemplated. I have three lines running down the hill, each a separate zone. The heads are 36 to 40 feet apart and I am running Hunter PGP's. I have great head to head coverage, but now the lower end is turning into a swamp. I am establishing new zoysia from seed in the area, so I am trying to keep the lawn moist everywhere. But when the top of the slope is thoroughly dry, the bottom is still swampy. I have reduced the nozzle size on all the downhill sprayers and cut the arc down on the middle bottom so that it does not cover the worst of the area. I think the worst of the problem is coming not from the system when it is running, but when it shuts off. When the valves close everything in the line drains out of the bottom sprayer. On the advise of my seed supplier, I am watering 3 times a day for a short duration, but that means that the swamp is getting 3 times as much line drainage as it normally would...or 6 times as much if you consider every other day as the "norm". Is there something I could add to the valves that would prevent the line from draining? Or should I not worry about it, since the three drains a day will only be for a couple of weeks? Any other thoughts or ideas? Thanks in advance for any insights you can offer.