(1) The purpose of this section is to describe the method of ranking the vulnerability of state freshwater stream, river, and lake environments, and portions thereof, to oil spills for purposes of applying the compensation schedule.

(2) Vulnerability of freshwater stream, river, and lake environments to oil spills is based on water type classifications and a habitat index.

(3) For each oil spill into a freshwater stream, river, or lake, a spill vulnerability score (SVS) is calculated. The SVS rates the vulnerability of public resources to spilled oil based on the spilled oil's propensity to cause acute toxicity, mechanical injury, and to persist in the environment. SVS is determined by multiplying the freshwater vulnerability score, which is based on the water type classification, by the habitat index score as described by the following formula:

Raw Spill Vulnerability Score (SVS) = FVS* HI.

(4) The final SVS score is found by rounding the raw SVS score calculated from the formula in subsection (3) of this section to the nearest 0.01 as follows: Decimals less than 0.005 shall be rounded down and decimals equal to or greater than 0.005 shall be rounded up.