Alcohol IS allowed in the forest. BUT... You cannot drive anywhere, on the trails or off, under the influence or with an open container. Alcohol is NOT allowed in most of the public camping and day use areas. There are some exceptions, Group Camp for example. If one large group wanted to have an event and reserve the entire area and wanted to have a party at the end of the day AFTER the trail riding is done, the group could apply for a permit that the District Ranger would have to approve. If you are primitive camping you can have all the beer you want but just like in town if you're drunk and rowdy and disturbing the peace and making fools of yourselves you may get a visit from the LEO. If you are primitive camping on the roadsides, where permitted (and sober of course) and are going to hit the trails best leave the beer cooler in camp. You will have less explaining to do if you do get stopped. If you are primitive camping in the trail system you can have alcohol and you obviously have to have it in the vehicle to get to camp. Just like coming home from the grocery store, if you get stopped, you have an open container, smell of alcohol and visibly drunk... you're busted. And once you set up camp leave it in camp and save it for the end of the day.
And one other thing... Pack it in. Pack it out! Because I'm tired of picking up...