Water Quality and Advocacy

The issues

“The Evenlode waters used to be crystal clear, then, one summer it seemed, they turned to look like oxtail soup. It is still obvious something is very wrong.”

John Pratt – Catchment Champion for the ECP

One of the biggest threats to freshwater comes from an excessive inflow of nutrients, in particular nitrates and phosphates. Nitrates and phosphates occur naturally in the environment, and healthy freshwater ecosystems usually have small amounts of these nutrients which help to sustain aquatic plant life. However, human activity on land can cause unnaturally high levels of nutrients to enter them.

In the Evenlode, the main sources of poor water quality are sewage and agricultural runoff. Our data shows that sewage accounts for 65–80% of total phosphate pollution in the catchment, with the remainder coming from agriculture. Over the last few decades there have been woeful declines in the quality of water in the Evenlode.

Raw and treated sewage

Raw sewage is only allowed to be spilled to the environment during exceptional weather circumstances. However, we get spills in normal rain, due to inadequate environmental permits. During rain events, and as a result of poorly maintained water and sewage infrastructure, too much rain gets into the pipework entering water Sewage Treatment Works (STWs). When this overload happens, treatment works are designed to divert untreated wastewater to storm tanks, and then spill to the environment. These spills are known as storm overflows. You can check when storm overflows are spilling in real time on Thames Water’s event duration monitoring (EDM) map.

The other issue is treated effluent. Many Sewage Treatment Works (STWs) are designed to deal with a ‘usual’ amount of wastewater, during dry weather flows. The problem is that most of the STWs in the Evenlode don’t remove excessive nutrients like phosphorous, nitrates, microplastics and other contaminants. These enter the river from the treated effluent. These nutrients cause a chronic problem for water quality which causes algae, diatom and fungal growth.

Additional treatment is required to better purify wastewater and rid it of excessive nutrients and chemicals.

Agricultural runoff

Historically, high amounts of phosphates and nitrates have washed off agricultural land into the rivers. Thanks to farmers and landowners in the Evenlode, and catchment sensitive farming incentives, the pollution from farming is greatly reduced. However, we want to see increased action and financial incentives to continue this reduction in farming pollution.  

The impacts

The poor water quality has had the following effects on aquatic life and river users:

• Fish stocks between 2010 and 2020, particularly coarse fish, have plummeted to 16% of the levels they were in the 1990s.

• Phosphate and nitrate results from citizen science are above recommended environmental limits.

• Riverfly insects (macroinvertebrates) abundance, collected by citizen science, are diminishing below sewage outfalls.

• Plant life like water crowfoot used to be seen extensively in recent decades, it is now seldom seen.

• Families who used to regularly enjoy the river for bathing and wild swimming, are now afraid of their life to get in. 

• Kayaking clubs on the Evenlode have abandoned their events due to E- Coli levels in the river.

The significance of water quality

When water quality is good in rivers it brings lots of benefits. This includes, but is not limited to: 

• Clean rivers allow ecosystems to thrive.
• Clean water is the most effective public health intervention to prevent disease.
• Clean rivers benefit local business and tourism.
• Clean rivers promote physical and mental well being.

What you can do

Through understanding which areas are being affected by pollution, we can direct targeted mitigation to improve water quality and protect freshwater environments.

If you want to help, there are lots of ways you can get involved, whether that’s as a volunteer citizen scientist, as a funder, or from home.

If you’d like to receive our “News from the Riverbank” newsletter, you can sign up by emailing sfrith@earthwatch.org.uk