I bought a house last summer and am having trouble with the back lawn irrigation system. There is a circle lawn with about a 48.5' diameter. There are 5 perimeter Toro impact sprinkers evenly spaced around 3/4 of the lawn and the last 1/4 has four spray heads. There is also an impact sprinkler about dead center in the lawn.

All of these are on the same valve and the radius reduction screw has been used in each of the rotors. Last summer the ground around the head in the low part of the lawn became just saturated mud. I dug up the head expected to find a broken line but found no such problem. Just toro funnypipe running off 18" at which point i stopped digging since the ground was getting dryer in that direction.

This spring the grass for the first two feet around the rotors is bright green and the rest of the lawn that the rotors cover is browning up. When they run the enclosure is filled with water and it spills out like an overfull cup. Is that normal for an impact rotor?

I've been educating myself over on irrigationtutorials.com and it looks like at the least i need to replace the valves in the rotors to insure uniform application, remove the radius reduction screw from the stream and i'll probably cap 3 of the spray heads and replace the fourth with another impact.

So, assuming i'm on the right track, any advice on why the impact rotors are spilling so much water and the lawn is only green right next to the heads? Note I'm not getting the 'donut' that is described in some pages, just the bright green saturated ground within a couple of feet and medium to little coverage elsewhere.But maybe it is the same cause, low pressure? All i know about the rate of flow is the valve is 1" and at least the last couple of feet to the head is 1/2" funnypipe. The water company says our standing pressure is about 45psi.

The kids want to play on a green lawn, any and all advice appreciated.