Dear Glenn D. Oliver, There ...

Dear Glenn D. Oliver,

There could be some considerations, if these ponds are 

Lined or just earthen ponds?

If lined, then with what, 

Clay+Lime

Any impermeable Geo-membrane is applied with properly lean concrete etc?

Normally if you do not want to use any chemicals, you may need to work on any of the solutions by applying Impermeable Geo-Membranes and/or Lining of Clay+Lime with proper application.

These are fresh water reservoir, must be lined/impermeable Geo-membrane application.

Also at Inlet, certain amount of NaOCl to be dosed which could disinfect the water.

To understand better, details of the reservoir, holding time etc. could be required.