Burrowing mayflies can develop densities of hundreds and close to 1000 per square yard. At those densities turbidities can evidently increase according to S.Banks and B.Condello. I think a way to introduce mayflies to your pond is to buy some from a local supplier or bait shop. You may have to have them special ordered from their supplier. You want local species not ones shipped in from several states away. Locally collected mayflies have a much better chance of establishing in your pond. Bait shops often call mayfly larvae 'wigglers'; adults are referred to as Mays, Upwings, Duns, Spinners, Dippers, Fish Flies.
Since the adult mayflies are winged and after their final molt they can fly to nearby bodies of water where they lay eggs. If conditions are acceptable the larva of hatched eggs will survive and populate that pond/lake. Stocking mayfly larvae into a pond increases the chances of mayflies laying eggs in a pond.
http://insects.tamu.edu/fieldguide/aimg3.html 
