Roseville is filled with parks where you can enjoy a nice picnic. There are also dog parks exclusively for our beloved pets. The closest lake here would be Lake Folsom. It is a beautiful lake where you can take your "best friend" for a nice walk. Whenever you're ready to move and enjoy Beautiful Roseville, give me a call. I've attached a link to Lake Folsom for you to review.
There are some places to eat at Sculpture park (behind Home Depot on Sunrise). The trail in Roseville is very nice with not a lake, but a stream. Check it out. It is very beautiful and a great walk.
Rocklin's trail and park ride (hit pdf): http://www.rocklin.ca.gov/government/service_n_facility/park
Folsom is indeed a nice place too and a great suggestion! Lots of great places to picnic.
Placer County Parks: http://www.placer.ca.gov/Departments/Facility/Parks.aspx
We have a few more items in the top navy bar on our website and in the orange side bar of fun things to do in Roseville and Rocklin (plus other neighboring cities).