In 1992 Tacoma turned off the fluoride. The 90th percentile lead levels dropped from 32 ppb to 17 ppb.
Quoting from Fluoride and Lead by Frances Frech:
Let us tell you a tale of two cities–Tacoma, Washington, and Thurmont, Maryland. Both of them saw significant decline in lead levels only six months after fluoridation was stopped. (In Tacoma, that was due to equipment problems, in Thurmont, it was a temporary ban by the city council.) Tacoma registered a drop of nearly 50% (20); in Thurmont it was 78%. To the best of our knowledge, no other explanations were offered. In Thurmont the ban is now permanent.
Unfortunately, Tacoma returned to fluoridating its drinking water and a battle continues over whether to stop it.
Dr. Debra Hopkins, Tacoma dentist describes how she decided fluoridation was not a good thing.