Michigan Administrative Code › Department - Environmental Quality › Water Resources Division › Water Resources Protection › Part 4 - WATER QUALITY STANDARDS › Section R. 323.1064 - Dissolved oxygen in Great Lakes, connecting waters, and inland streams

Current through Vol. 24-12, July 15, 2024
Rule 64.
(1) A
				  minimum of 7 milligrams per liter of dissolved oxygen in all Great Lakes and
				  connecting waterways shall be maintained, and, except for inland lakes as
				  prescribed in R 323.1065, a minimum of 7 milligrams per liter of dissolved
				  oxygen shall be maintained at all times in all inland waters designated by
				  these rules to be protected for coldwater fish. In all other waters, except for
				  inland lakes as prescribed by R 323.1065, a minimum of 5 milligrams per liter
				  of dissolved oxygen shall be maintained. These standards do not apply for a
				  limited warmwater fishery use subcategory or limited coldwater fishery use
				  subcategory established pursuant to R 323.1100(11) or during those periods when
				  the standards specified in subrule (2) of this rule apply.
(2) Surface waters of the state which do not
				  meet the standards set forth in subrule (1) of this rule shall be upgraded to
				  meet those standards. The department may issue permits pursuant to R 323.2145
				  which establish schedules to achieve the standards set forth in subrule (1) of
				  this rule for point source discharges to surface waters which do not meet the
				  standards set forth in subrule (1) of this rule and which commenced discharge
				  before December 2, 1986. For point source discharges which commenced before
				  December 2, 1986, the dischargers may demonstrate to the department that the
				  dissolved oxygen standards specified in subrule (1) of this rule are not
				  attainable through further feasible and prudent reductions in their discharges
				  or that the diurnal variation between the daily average and daily minimum
				  dissolved oxygen concentrations in those waters exceeds 1 milligram per liter,
				  further reductions in oxygen?consuming substances from such discharges will not
				  be required, except as necessary to meet the interim standards specified in
				  this subrule, until comprehensive plans to upgrade these waters to the
				  standards specified in subrule (1) of this rule have been approved by the
				  department and orders, permits, or other actions necessary to implement the
				  approved plans have been issued by the department. In the interim, all of the
				  following standards apply:
(a) For surface
				  waters of the state designated for use for coldwater fish, except for inland
				  lakes as prescribed in R 323.1065, the dissolved oxygen shall not be lowered
				  below a minimum of 6 milligrams per liter at the design flow during the warm
				  weather season in accordance with R 323.1090(2) and (3). At the design flows
				  during other seasonal periods, as provided in R 323.1090(3), a minimum of 7
				  milligrams per liter shall be maintained. At flows greater than the design
				  flows, dissolved oxygen shall be higher than the respective minimum values
				  specified in this subdivision.
(b)
				  For surface waters of the state designated for use for warmwater fish and other
				  aquatic life, except for inland lakes as prescribed in R 323.1065, the
				  dissolved oxygen shall not be lowered below a minimum of 4 milligrams per
				  liter, or below 5 milligrams per liter as a daily average, at the design flow
				  during the warm weather season in accordance with R 323.1090(3) and (4). At the
				  design flows during other seasonal periods as provided in R 323.1090(3), a
				  minimum of 5 milligrams per liter shall be maintained. At flows greater than
				  the design flows, dissolved oxygen shall be higher than the respective minimum
				  values specified in this subdivision.
(c) For surface waters of the state
				  designated for use for warmwater fish and other aquatic life, but also
				  designated as principal migratory routes for anadromous salmonids, except for
				  inland lakes as prescribed in R 323.1065, the dissolved oxygen shall not be
				  lowered below 5 milligrams per liter as a minimum during periods of
				  migration.