I've traveled to remote places, many in the "third world" and ozone is widely used to "purify" water. Mostly this means rain or river water collection, then ozone is bubbled through the water to kill any wee-beasties that might make someone sick. Does anyone here know if ozone will “neutralize” other contaminants? I know it works great on biological pathogens, but what about chemical pollutants? Fertilizers, heavy metals, pesticides and/or herbicides?

To be specific, I live in a Midwest urban environment; we have many lakes (very green in the summer time due to fertilizer runoff from yards), several creeks and two major rivers. In the event of loss of our water utility, could water be collected from those sources and made potable by ozone?

Ozone is poisonous. Thats why it works to kill most biological pathogens.
Its also why they put ozone filters in laserprinters and photocopiers etc.

Yeah, it's not good to breath. The good thing is it doesn't leave any residue. The O3 molicule is highly reactive, but quickly “quenches” to regular O2. It’s the process of loosing the extra Oxygen that makes it toxic. I’m wondering if this high energy reaction can “detoxify” chemical contaminants?

Nope.

Ozone is an oxidizer - all it does is oxidize. For reference, chlorine bleach is an oxidizer. Most chemical contaminants will not be rendered safe by oxidizing. Many will not be removed by filtering (e.g. charcoal), either. If you suspect chemical contamination, you're better off looking for another water source.

Ozone is an excellent drinking water disinfectant. However, ozone will not render water contaminated by fertilizer runoff or organic chemicals safe. Generally accepted methods (at least at the municipal treatment scale) to remove nitrates/nitrates include methods like ion exchange, reverse osmosis, and electrodialysis. Methods to remove organic compounds like benzene and toluene generally involve a combination of packed tower aeration and activated charcoal. Herbicides/pesticides generally require activated charcoal to remove.

Speaking of the Midwest, Milwaukee converted their antiquated water treatment system to a state-of-the-art system which incorporates the use of ozone after the cryptosporidium outbreak back in 1993. They may have the safest municipal water in the country nowadays.