They carefully sprayed Yellow Fish symbols next to Helston’s historic kennels and surface water drains, to clearly mark the places where water empties straight into the River Cober. The Yellow Fish symbols are to remind people that it should be ‘Only Rain Down the Drain!’

This Environment Agency initiative helps to reduce river pollution. Food and other organic waste emptied into surface water drains will get to the nearest stream, leading to rapid growth of naturally occurring algae and bacteria. This growth can block out sunlight and use up dissolved oxygen which can kill off sensitive wildlife species like dragonfly and mayfly larvae. The larvae and adult forms of these insects are food for brown trout, swallows and several bat species, so anything other than rain in the surface water drains can have a devastating effect right up the food chain.

Ben Osborne is the year 3 teacher at St. Michael’s and was enthusiastic about the day,

“This kind of thing brings science to life for our school children. The event gave them a chance to see how our behaviour affects wildlife, but also meant they could do something positive to help protect it. It helped them understand that we all need to take responsibility for protecting our local environment, as well as setting a good example for us grown-ups!”

Yellow Fish is part of a bigger effort by multiple organisations to bring benefits for water quality, wildlife and people in and around the River Cober. The river is affected by the land which drains into it, so work is done across the whole Cober drainage basin – a wide patch from Four Lanes down to Loe Pool. The Loe Pool Forum (loepool.org) coordinates conservation work across the area which involves Cornwall Wildlife Trust, National Trust, Natural England and the Environment Agency.

Cornwall Wildlife Trust’s wider work in this area is funded by the Environment Agency and South West Water and supports farmers to manage their land more sensitively for wildlife and water, as well as part-funding infrastructure improvements. Two new roofs over farmyard manure stores have been constructed recently, which stop nutrient-rich dung washing into the river during heavy rain. Farm nutrients starve river species of light and oxygen in the same way as waste emptied down the drain; so the roofing protects wildlife but also keeps a stockpile of muck which the farmer can spread on the fields in dry weather.

Farmers are also making land management changes, like planting a wider variety of deep-rooted grasses and flowers. Wildlife including pollinating insects benefit from this exciting mix of species, and the cows get a more varied diet which can help fend off illness. Deeper rooting plants make the soil spongy, holding onto water better and then releasing it slowly. More fields like this can catch pollution before it gets to the river, as well as ‘slowing the flow’ during heavy rain which helps to reduce the risk of flooding in Helston.

Organisations like Cornwall Wildlife Trust are supporting farmers, businesses and local communities to gradually improve the River Cober and Loe Pool for wildlife, water quality and people. The Trust is always keen to hear from individuals or groups looking to volunteer. There are several opportunities at the moment, including helping with the Riverfly project. Riverfly volunteers catch small river creatures like insect larvae in a net then study the diversity of species found. These creatures are very sensitive to pollution so the results help us to better understand changes in water quality. Please contact upstreamthinking@cornwallwildlifetrust.org.uk to get involved or for more information.