(a) No permit for the discharge of treated wastewater into the Ouachita River commencing at or downstream of the H.K. Thatcher Lock and Dam in segment 2D of the Ouachita River Watershed shall authorize a total phosphorus limit in excess of the following:

1. (1) A proposed permit with a design flow of less than or equal to thirteen and five-tenths (13.5) MGD shall have a total phosphorus mass limit calculated using a total phosphorus concentration of one milligram per liter (1.0 mg/L) year-round; and
2. (2) A proposed permit with a design flow greater than thirteen and five-tenths (13.5) MGD but less than twenty (20.0) MGD shall have a total phosphorus mass limit calculated using a total phosphorus concentration of one milligram per liter (1.0 mg/L) for the months of November through June, and seven-tenths milligram per liter (0.7 mg/L) total phosphorus for the months of July through October.

(b)

1. (1) The above mass calculations are considered to be on a monthly average basis.
2. (2) A daily maximum mass limit, if applicable, will be one and five-tenths (1.5) to two (2.0) times the monthly average mass limit.