It is not the state it is the city. The Indiana Code gives cities the right to restrict the possession and carrying of firearms on city owned property. Indianapolis has an ordinance that specifically bans firearms from any property owned or operated by the IndyParks system. This includes not only parks but city owned golf courses and recreational facilities. If you search the ordinances of most cities in Indiana they have ordinances against carrying in parks. Also a city does not need an ordinance to restrict firearms on their property, they can do so as a matter of policy.So what the state is saying, through their parks service, is that it is ok for criminals to be armed on the Monon but not honest persons.
Time for some letter writing!