There is variable effectiveness with alum treatment.  Studies have shown internal P loading decreased by an average of 67% and lasted an average of 8 years.  These are promising statistics.
	Although it is very effective, is also fairly expensive.  Avg is $450, but can be as high as $700 per acre.  Keep in mind lake is over 600 acres.
	The chemical and depth requirements for the treatment match the lake characteristics, but this method still must be carefully tested and monitored, and prior control of P influx must occur for effective results.