Finally, a small victory for hunters.

[rickOshay]

Here is a link to an interesting summary on lead mobility by those exacting scientific types at SAAMI:
http://www.saami.org/specifications_and_...bility.pdf

Their summary on page 12 is:

Studies published to date indicate a general lack of lead mobility under most environmental conditions. From the relatively few lead mobility studies conducted at shooting ranges, pH appears to be an important factor. Surface water pH values of ≥7.0 tend to indicate restricted lead mobility whereas pH values of ≤6.5 tend to indicate enhanced lead mobility. Attempts to statistically correlate lead concentrations in water with pH, alkalinity, or shot density, however, have not been successful, likely due to complex interactions of several other environmental factors.