The City/Government controls the channel and has complete editorial control. You need to make this clear with viewers at the beginning and it must be established quickly. If you don't, the channel could be considered a "public forum." If considered a public forum, everyone has a right to be on the channel, including every political candidate for every political party, and/or extremist groups. If this is not your goal, you want guidelines and policies in place fast.
Don't be tempted to let a non-government user on the channel before the policies are in place, no matter how good an idea may seem at the time. Use your policies as a basis for a refusal to air unacceptable material, or material that runs counter to policy.
A government access channel is not a public access channel. People do not have first amendment rights to appear on a government channel. Just as none of us can submit a show to NBC and expect it to air in prime time. The same is true of government access channels. Any program can be submitted for consideration -- if it meets the technical and content standards established by policy -- the final decision is made by the City, via the GATV manager, who has full editorial control.