Class

Quality

BMWP-PA index

Significance

Alert Signal

I

Good

>120

101 - 120

Very clean water

II

Acceptable

61 - 100

Non-contaminated water

III

Regular

36 - 60

Moderately polluted waters

IV

Bad

16 - 35

Very polluted water

V

Wretched

<15

Severe contaminated water