Right here at RR you can go to the home page and click on the left side of the home page under Radio Features then click on "RR Database" then click on "CA" then click on "Lake" county to get: http://www.radioreference.com/modules.php?name=RR&ctid=199
That page has some agencies in Lake County with their freqs., not any codes though.
Here's a list of licensed users in Lake County with their FCC callsigns: http://tinyurl.com/m7cyn
Just for info, Lakeport PD is dispatched by the SO and are the "2" units. As in 2paul1 and so forth. And Clearlake is all "3" units.
Also I don't see anything listed for Hidden Valley Lake, thier security is on 464.4500mhz.