(1) The department shall use the following criteria to determine whether to implement angling restrictions:
(a) angling pressure as determined by the department has the potential to contribute to excessive fish mortality; and
(b) one or more of the following environmental conditions has been determined by the department to exist:
(i) on streams managed for salmonids daily maximum water temperatures reach or exceed 73 degrees Fahrenheit at any time during the day for three consecutive days;
(ii) stream or river flows fall to or below the 5th percentile of daily mean values for this day flow level based upon hydrologic records for that water body;
(iii) in bull trout streams designated by the department, a daily maximum water temperature equal to or exceeding 60 degrees Fahrenheit at any time during the day for three consecutive days; or
(iv) water conditions meet the criteria for angling restrictions as stated in a Drought Management Plan.
(2) A fishing closure may be implemented when:
(a) conditions of (1) develop;
(b) dissolved oxygen is equal to or less that 4 ppm when measured in the early morning before sunrise;
(c) water conditions meet the criteria for fishing closures as stated in a Drought Management Plan; or
(d) other biological or environmental conditions such as, but not limited to, water body pollution, disease, and shifts in angling pressure exist that the department determines have the potential to adversely affect the fishery.