Agriculture, importantly cattle in the Brue area, is responsible for two thirds to three quarters of water pollution, commonly through heavy rain falling on farmland, mixing with faecal matter either through slurry application or directly from cow pats, and running into the waterways.
There are Government guidelines for managing contaminated runoff here.
When agricultural practices change so that cattle and pigs are kept indoors, it is necessary to collect their faeces in slurry pits, and the slurry is disposed of by spreading it on the fields as fertiliser. Rain can move nutrients from the fields to waterways, causing pollution.
Slurry pits are dangerous to life and health of farm workers, and are a source of air pollution, giving out two greenhouse gases (ammonia and methane, which are valuable energy sources if properly managed) and hydrogen sulphide and CO2 (the second most powerful greenhouse gas).
There is therefore an opportunity to manage slurry far more ecologically and economically.
A study by the University of East Anglia has shown that anaerobic digestion of cattle slurry could save about £400million a year in fuel costs. Technology to do this on farms is on the market (put “slurry converts to biogas” into a search engine). The hold up is in the initial costs of installation, and there is a clear precedent for Government to invest in these costs.
One of the problems on the Levels is that farmers want the water table (i.e. the level at which a hole dug in the soil begins to fill with water) to be low, and bird conservationists want ground water to be high. Delicate and detailed negotiations are needed to resolve this conflict.