Is this just a day pack I'm assuming? Add your lunch and water for the day you've got around another 10lbs probably. I keep my total day pack right around 18-20lbs, so you're a little bit heavier than what I carry, but it's better to have everything you may need.
Remember, the more weight you add the slower and less you're gonna move. Don't be afraid to drop your pack if you need to cover ground quick for some reason, just make sure you can get back to it.
-Jake