Table 1: BMWP classes, scores, categories, and result interpretation (adapted from Armitage et al., 1983 [30], and Alba-Tercedor, 1996 [29]).

ClassBWMP scoreCategoryInterpretation

I>150GoodVery clean water 
101–150Clean or not significantly altered
II61–100AcceptableClean but slightly impacted
III36–60QuestionableModerately impacted
IV15–35CriticalPolluted or impacted
V<15Very criticalHeavily polluted