The following seasons will be used in applying the early life stage present chronic criteria noted in Table 3b, "Chronic Criterion for Ammonia in Iowa Streams - Early Life Stages Present."

1. For all Class B(CW) waters, the early life stage will be year-round.
   
   
2. For all Class B(WW) significant resource waters, the early life stage will begin in March and last through September except the following:
   • For the following, the early life stage will begin in February and last through September:
     • The entire length of the Mississippi and Missouri Rivers,
     • The lower reach of the Des Moines River south of the Ottumwa dam, and
     • The lower reach of the Iowa River below the Cedar River.
     
     
     
   • For the following, the early life stage will begin in April and last through September:
     • All Class B(WW) waters in the Southern Iowa River Basin,
     • All of the Class B(WW) reach of the Skunk River, the North Skunk River and the South Skunk River south of Indian Creek (Jasper County), and the Class B(WW) tributaries to these reaches, and
     • The entire Class B(WW) reach of the English River.
   
   
   
3. For all Class B(LR) waters, the early life stage will begin in April and last through September.
   
   
4. For all Class B(LW) lake and wetland waters, the early life stage will begin in March and last through September except for the Class B(LW) waters in the southern two tiers of Iowa counties which will have the early life stage of April through September.