How much lead in a boat is ok?

I currently have about 650 lbs of lead that I keep in my boat full-time, both when trailering and in the water, currently 350 in the back and 300 in front. I live about 40 minutes from the delta. Is this ok or too much? I haven't run into any issues when trailering or any damage to the boat hull in the water, but I'm interested to hear what is considered a safe amount of lead to keep in your boat. I have a tandem axel trailer. Thoughts?