I have looked around and can not find any farms that are Irrigation Circles and I have never seen any in MDs or CJs.
(https://www.sc4devotion.com/forums/proxy.php?request=http%3A%2F%2Fimg137.imageshack.us%2Fimg137%2F9259%2Fcloseupofcirclelw5.jpg&hash=9d0a8f1e9f52f6448a024992620e679070be0225)
Has anyone tried to make these or are they out there somewhere? The size of them might keep people from making them (actual scale would be somewhere around 40 x 40 squares in Sim City). They are everywhere in the Midwest of the USA.
(https://www.sc4devotion.com/forums/proxy.php?request=http%3A%2F%2Fimg137.imageshack.us%2Fimg137%2F4206%2Firrigationcirclesdt7.jpg&hash=2cf8d2e973ba1c41f486d7ca6c7708899d912153)
I suggest you take a look at 3RR, there are a lot of post about CPI there http://sc4devotion.com/forums/index.php?topic=112.msg102015#msg102015, david and threestooges are trying to recreate them
(https://www.sc4devotion.com/forums/proxy.php?request=http%3A%2F%2Fimg253.imageshack.us%2Fimg253%2F6607%2Fteaser01dp0.jpg&hash=8c3f7d195012459433adae1045f78aa18346fe5e)
They are now, of course, released on 3RR here [linkie] (http://sc4devotion.com/forums/index.php?topic=112.msg136083#msg136083). They are about half the size of the monsters shown below at 1/4 mile (.4 kilometers) across (24x24 gridsquares), but do give the effect.
Enjoy!
David