Diazinon is highly toxic to aquatic organisms; concentrations as low as  0.003µg/l have been shown to negatively affect invertebrates and can also affect key species such as salmon. Herbicides such as MCPA are moderately toxic to aquatic plants. The process of removing pesticides from drinking water quality is costly and reduces the overall efficiency of the water treatment works.



The River Wyre provides drinking water for an estimated 650,00 people. In 2015 it was designated a drinking water safeguard zone and therefore measures are being taken to reduce the amount of pesticides which are entering the river. MCPA and Diazinon in particular have caused the standard for drinking water quality to be exceeded on a number of occasions.

In 2018 and 2019, in partnership with United Utilities, the Environment Agency and Catchment sensitive farming, the Wyre Rivers Trust undertook a programme of monitoring along the upper Wyre and its tributaries to understand more about the problem of pesticides in the catchment. We will continue our monitoring in 2020 and will be working with landowners to find ways to  reduce the amount of pesticides going into the river.


Franklaw Safeguard Zone

If you would like to view the full report please email lucy@wyreriverstrust.org

How to use pesticides safely

Why is it important?

How do pesticides end up in the river?

Herbicides may be washed off treated fields, roads and railways over land or through drainage channels and subsurface drains. Spillages can result in pesticides entering watercourses directly or surface water drains from handling areas such as farmyards. Spray drift from applicator booms can also result in pesticides entering directly into watercourses. 

Diazinon often enters watercourses from leakages from dip bath or drips from treated sheep or drainage pens. Improper disposal can also result in pollution.