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Table 1 OPAL Water Survey invertebrate classification and ‘Invertebrate group health’ score based on the tolerance of the group to a range of stressors. Below is a comparison of descriptors for the derived pond health score ranges for the OPAL Water Survey (2010) and the 2014 Big Pond Dip [54]

From: Quality control in public participation assessments of water quality: the OPAL Water Survey

Tolerance class Groups Group health score
High sensitivity Cased caddisfly larvae; Caseless caddisfly larvae; Dragonfly larvae; Damselfly larvae; Alderfly larvae 10
Medium sensitivity Mayfly larvae; Water beetles (adults and larvae); Water bugs (including water boatmen, water scorpions, water stick insects etc.,); Pond skaters; Water shrimps 5
Low sensitivity Water slaters (water hoglice); Worm-like animals (including chironomid larvae; flatworms; leeches; worms etc.,); Water snails (spired; limpets; planorbids) 1
Pond health score OPAL Water Survey (2010) description Big Pond Dip (2014) description
0–5 Poor or ‘could be improved’ Not yet great
6–30 Quite healthy Good
31 and above Very healthy Brilliant