Wetlands
100 years ago the Broads were full of big plants like reeds and water lillies
People digging up peat helped to create Britain’s largest wetland, the Broads.
We now dig up tonnes of mud to help restore wildlife to this internationally important wetland.
A murky tale of sewage, cows and algae
A hundred years ago you could row a boat across the sparkling clean water of the Broads, with water lillies, reeds and other large water plants along the banks and tangling around your oars.
Since then more people living around the Broads have made more nutrients get into the water, in particular phosphates and nitrates. Phosphates come from human waste that goes through sewage works and animal waste from farms. Nitrates come from fertiliser used on farms to make plants grow more.
The high level of nutrients makes algae grow, which makes the water cloudy. Plants like water lillies can't get enough light in the cloudy water, so they die. Every autumn when all the tiny algae die, they fall to the bottom as nutrient-rich sludge.
With no plants to hide in all the insects, snails and other invertebrates in the water get eaten by fish. When they've all gone there is not enough food to feed big fish, so only the little fish are left.
With no plants growing by the banks, and no plant roots to hold the soil together, the waves from boats wash the soil from the banks into the water. This mud gets added to the alagae sludge at the bottom and the water gets shallower.
How do we get the clean water back?
We are doing lots of different things to get the Broads back to having clean water, big plants and lots of wildlife:
Over 160 Olympic-sized swimming pools worth of mud has been dredged out of Barton Broad.
1. Stop the nutrients getting into the water
We've already lowered the nutrients getting into the water, by asking the water companies to make the sewage treatment works remove more phosphate and by encouraging farmers to use less nitrates on their land.
2. Dig up the mud
Even though there's less nutrients getting into the water, there's loads of it sitting at the bottom, in all the sludgy mud built up by the dead algae and the eroded riverbanks. We've dredged tonnes and tonnes of mud from the bottom of the Broads to stop it releasing nutrients into the water.
We dump the mud onto fields and once its dry it makes great soil for growing crops in!
In just one day, water fleas can filter the water of an entire broad!
3. Zap the fish
Water fleas are tiny animals that eat the algae we want to get rid of. But water fleas get eaten by fish. So we zap the fish with an electric current that stuns them, then we scoop them up in nets and put them into nearby rivers. We use plastic fish walls to stop them getting back in, and then the water-fleas multiply and eat up loads of algae.
4. Protect the plants
With the algae gone, water plants start to grow in the clear water. We keep the fish out and protect the plants with wire cages to stop the birds eating them. When the plants are big enough we can take the cages away and let the fish back in, as the plants provide hiding places for the water fleas and other insects to hide.
Further information
- Broads restoration - including full Lake Restoration Strategy
- Barton Broad restoration project - including history of the broad, map, project details and facts and figures
- Water quality and restoring the Broads factfile - PDF leaflet aimed at students at GCSE level and above
