The tennis court is whats called a hydro court. There are perforated PVC pipes run underneath the clay and they drip water out of them, this keeps the surface damp.
About 25 year's ago the tennis shop at the club i was working at had just installed two clay court's with sub-surface irrigation like that. They thought the clay was too dry so they wanted me to turn up the water. There was a 1" valve for every line under the court. It seem's like there was a line every 8', i really don't remember. The valve's were halfway open, i opened them up 25% more. I came back 2 hour's later and the court's looked like the surface of a lake on a windy day, very wavy. They had to close those thing's for 2 day's and roll the court's for about 4 hour's. I learned something that day.