On this same line Yellowstone lake requires nonlead weights. This includes your downrigger weight.

we have steelshot for waterfowl hunting due to waterfoul ingesting the lead shot and causing mortality. I doubt many fish are ingesting the lost lead.

I also do not doubt that it will not be many years before we have to use nonlead weights.

If you want to see just how much lead can be deposited on a given snag go to the Willie Boat factory and check out the "Trophy" snag they have displayed on the wall. A 4'x2'x10' collection of lead and corkies and mono. Had to weigh over 500 lbs. and that was just one snag.