text: are you sure there is even a Walnut Creek Open Space? Its not listed on the City of Walnut  Creek Open Space website. It seems that Walnut Creek Open Space is just the name given to all their open space holdings. Here's some websites for reference, of which the whole area here named Lime Ridge Open Space appears to be a part of. 
  http://www.wcosf.org/enjoy/maps.html
  http://www.walnut-creek.org/departments/public-works/open-space-facility-formmatted-list
  
  It appears from the official map that Lime Ridge should at least be split into North and South areas. I'll at least do that if you don't know anything about the other thing. 