B. Within ninety days following the end of each accounting period a person who delivers a combination of surface water or effluent, or both, and groundwater for uses by cities, towns, private water companies, industries, farms or other users shall provide the director with an accounting for water during the past accounting period which shows the following:

1. 1. All surface water provided to each class of user and each farm.
2. 2. All groundwater provided to each class of user and each farm.
3. 3. All effluent provided to each class of user and each farm.

C. If a person delivers water to a user through a delivery system that commingles groundwater with surface water or effluent, or both, the amount of groundwater charged to the user pursuant to the accounting in subsection B shall be computed as follows:

1. 1. Determine the total amount of water delivered to the user through the system during the accounting period.
2. 2. Determine the amount of surface water and effluent that would have been delivered to the user through the system during the accounting period if no groundwater had been delivered through the system.
3. 3. Subtract the amount determined pursuant to paragraph 2 from the amount determined pursuant to paragraph 1.