The score has held steady
Steady Scores held near 16.5 before 2013 and 16.6 since; the overall score shows no trend.
16.5 → 16.6mean SOS score, before and since 2013
3.4points between the two sites on the same day
The SOS score adds up the pollution-sensitive, less-sensitive and tolerant animal groups found in a survey. Single surveys range from 9 to 26, but the average has not moved.
The two sites, a few hundred metres apart and sampled on the same day 10 times, differ by 3.4 points on average. A change smaller than that is within sampling noise.