How does turbidity affect dissolved oxygen?
According to this document, turbidity and oxygen content can be correlated because the more microbes in the water, the more turbid the water is, and the less oxygen is left (because they breathe it).

But a correlation is no cause-effect relationship. Both are linked in the particular case of microbes because they affect both by their presence.

Not a reliable method at all. More oxygen in the water does not mean it is potable. If you let sit a bucket of water contaminated with microbes, the oxygen levels will drop over time, but if you stir the water, you re-dissolve some up to saturation levels, but you still have the microbes present. 

You may want to evaluate the oxygen demand, or the biomass (absorption at 600nm), centrigugate and evaluate visually, etc.