Report from Wil Harvey, Wenhaston River Group
The ‘heat’ maps of our analyses of the Blyth and tributaries for July.
Not surprisingly, the pattern of pollution is similar to June, with the river conditions reflecting the drought. However, visual signs of pollution, particularly surface scum and duckweed growth were more evident.
The river temperature ranged from 17.1 C to 22.3 C, but the two new sample sites (outfall pipes) at Laxfield recorded 25.6 and 26.3 C, respectively. These higher temperatures – together with very high ammonia, E coli, & dissolved solids readings, are strongly indicative of sewage effluent.
Note: it is generally acknowledged that river temperatures above 20 C place increasing stress on aquatic invertebrates and fish. The current hot, dry weather combined with low water levels and low flow rates will exacerbate this temperature rise.
Wil Harvey
Wilder Wenhaston River Group