Which of the following most logically completes the passage?
The EPA released a report on Wednesday indicating that increasing incidence of algal blooms in a lake close to Eleusis is linked to fertilizer washed into the water from nearby farms after periods of heavy rain. To prevent reoccurrence of the blooms, the agency implemented regulations that will go into effect in two years mandating the use of another fertilizer shown not to cause algal blooms if introduced into water sources.
Though area farmers anticipate making the switch within one year, the agency does not expect that the incidence of algal blooms will decline before its regulations take effect, because _______.