Looking for pasture in Northern California!!

Lately I've been very busy trying to organize pastures for our horses. It meant many hours on the roads driving between Napa, and Shasta County. During this winter we've had more horses than ever before, and the pastures haven't been enough for them all. We've been moving them around, trying to utilize the richest pastures for the horses that needs it the most, and supplemented with hay ~ a lot of hay! With these hay prices we buy hay for more than $500/week. Considering that most of our horses are on pastures that is a lot of money. We're looking to buy/rent/lease more irrigated pastures.The winter time is hard on many of the older rescue horses we have. They've had a very rough life and several are in their twenties. Most of these horses benefits from a combination of a free choice of high quality hay, and nibbling on the pasture grass that's available. 

I'm looking forward to a more practical solution to the pasture issue. That would mean more time actually taking care of and riding the horses. Do you know of available pasture land (around 100acres or more would be preferable) in Northern California? Please send me an email mmarianorthcutt@gmail.com! Thank you!