UK river pollution monitoring is 50 years out of date, say researchers

The monitoring of UK rivers hasn’t been updated since the 1970s and gives just a snapshot of the state of water quality, hampering efforts to clean it up.

The UK’s four nations have similar methods when it comes to monitoring rivers. In England, for example, the Environment Agency (EA) collects water samples once a month to measure levels of pollutants such as phosphates and nitrates. These can lead to a reduction in oxygen in the water that suffocates aquatic animals and plants.

Out of the UK’s nearly 1500 rivers, samples are collected at more than 1000 fixed sites, usually in the middle of the week between 9am and 4pm, says Pete Lloyd, a former EA official. This doesn’t give an accurate picture and may “only reflect the condition of the river for a few minutes”, he says.

Most pollutants enter rivers after it has rained, either by running off farmland or when raw sewage is diverted away from sewer networks so they don’t overfill and back up into homes, says Lloyd. With the current sampling methods, which have been in place since the 1970s, it is a coincidence if the data collection happens after it has rained.

“I understand why we monitored rivers this way 50 years ago – we didn’t know what actually caused problems for rivers, so random sampling sounds like a good idea,” says Lloyd. “But now we know the problems, why aren’t we more targeted with our monitoring? The system is decades out of date.”

According to Penny Johnes at the University of Bristol, UK, this inadequate sampling means our knowledge of UK rivers has “absolutely colossal” uncertainties. In 2007, she looked at 39 years’ worth of daily data on the rivers’ total phosphorus concentrations, defined as a measure of the pollutant in all forms. High total phosphorus can lead to algal blooms, which can deplete water oxygen levels, block sunlight and release harmful toxins.

To mimic the EA’s sampling, Johnes analysed data collected from different rivers on the same date each month, comparing this with the original dataset. She found that only looking at water quality once a month misses important information about when phosphorus concentrations change. “The way in which we monitor rivers is highly variable in time and space,” says Johnes. “It’s not fit for purpose and hasn’t been for a long time.”

While Johnes looked at total phosphorus, the UK’s regulatory bodies don’t routinely monitor for this in rivers, despite the government wanting to cut its runoff from farms into water bodies by at least 40 per cent by 2038. The EA, for example, only monitors rivers for reactive phosphorus, a soluble form, which a spokesperson says is the type most readily taken up by plants and algae. But Johnes says non-dissolved phosphorus that runs off from farms makes up two-thirds of the pollutant in UK rivers.

The bodies also don’t regularly monitor rivers for some of the chemicals in consumer goods and pharmaceuticals, says Johnes. The EA spokesperson says it screens for more than 1600 chemicals, but Johnes says thousands of newly synthesised chemicals could still be running into rivers unmonitored.

Speaking on behalf of all of the UK’s regulatory bodies, the EA spokesperson says they are working with the pharmaceutical industry and research bodies to set up a working group that screens for pharmaceuticals in sewage discharge.

According to Johnes and Lloyd, the solution to the river-monitoring uncertainties is to introduce more-intensive water quality checks and to be more targeted with when samples are collected. “If you want to find out how agriculture is affecting a river, then you need to collect samples after rainfall,” says Lloyd. “If you want to find out how sewage is affecting a river, then you need to collect samples near a sewage overflow after rainfall,” he says.

Much of this could be done via electronic sensors that fit into riverbanks and automatically record pollutant levels, says Johnes. Some of these are already in place, but more are needed, with more rigorous analysis of their data, she says.

The recent uproar around sewage dumping in UK rivers, a problem that has probably been around for years before becoming a popular issue, is a good example of how inadequate water quality monitoring has let the public down, says Lloyd.

This changed when Peter Hammond, a former maths professor, lodged a freedom of information request that found untreated sewage had been dumped 240 times into the Windrush river in England over the past three years. He then sent dozens of similar requests to water firms around the country, revealing the scale of the problem. “Our monitoring system never picked it up,” says Lloyd. “If it had, maybe we could have done something about it by now.”