The Old Mill Dog Park is a great addition to the city of Bend. However, it has a design flaw. Since there is no dedicated small dog play area, large and small dogs are forced to share the space, and often, their play is dangerously rough. The park is large enough to partition a safe, small dogs (30 lbs. and under) only area.
As the owner of a friendly and well-behaved retired racing greyhound, I've spent upwards of an hour waiting for small dogs to clear out of the park so my dog can go in without causing alarm to small dog owners. I wait because, although my dog is not aggressive, her breed is trained to chase and hunt small prey, and I won't take the chance of her grabbing a small dog, even at play.
It would be wise to have a separate and safe area for small dogs. Many of them would be happier there, and dogs like mine would have an opportunity to play, too. I can't speak for small dog owners, but I've had conversations with many of them who would like to see a safe, small dogs only play area.