Making blue flags fly high at the Yorkshire seaside

On a bitterly cold autumn day a bracing onshore wind is whipping up Scarborough's North Bay, and delighted surfers are riding the white crests or bobbing around like seals waiting to catch the next wave.

At the far end of the promenade, next to where Scalby Beck runs into the sea, a man with a slightly weatherbeaten face and glasses is eyeing the waves and the stiffening breeze with concern. He has been seen off the Yorkshire coast a lot this year and from a distance his gear may suggest he's out laying crab and lobster pots.

But he looks more like a yachtsman than a fisherman and the name of his craft, C.R.E.H. Tracer, is decidedly un-fishing community. The initials mean Centre for Research into Environment and Health, and the only "live" catch he's looking for can't be seen with the naked eye. They are microbes. This is Professor David Kay, one of Britain's foremost experts on the quality of water used for recreation.

Based at the University of Aberystwyth, he is engaged by Yorkshire Water to run a series of tests along the coast, the results of which are helping to guide an ambitious 110m investment programme which should make Yorkshire's beaches among the cleanest in Europe.

Yorkshire has 20 officially designated bathing beaches on its 60 miles of coastline, and from early May to late September weekly water-quality tests are carried out on them by staff from the Environment Agency.

Last summer, the coveted Blue Flag – the ultimate symbol of clean water and safe bathing – was awarded to only four of the beaches: Whitby West Cliff, Scarborough North Bay, Filey, and Bridlington North Bay. Three others at Bridlington South Bay, Hornsea and Withernsea lost their Blue Flag status.

This was mainly because Britain had a wet summer in 2009 and the outcome was more agricultural run-off into drains and streams and some sewage pumping stations were unable to cope with the water flooding through their systems.

This has raised two main questions which Professor Kay has been asked to answer. Where does the pollution come from that can affect a beach's rating, and how does it behaves once it's in the sea?

Yorkshire Water's discharges of sewage (the company prefers the term "waste water") through outfall pipes that are almost one mile offshore, are only part of a complex story. There are other factors, the largest being the run-off into drainage ditches, rivers and streams from the faeces of livestock, or from muck spreading for fertiliser.

When Professor Kay and his team have been at sea this year, they have been running three different tests at a large number of monitoring sites from above Staithes down

to Withernsea.

All the tests are designed to find out the fate of every discharge from the Yorkshire coast into the North Sea. Where does the tide carry it, at what rate does it dilute, and under what conditions could it affect the quality of bathing water?

One of the tests is the use of sonar devices which sit on the seabed – five at each monitoring site – and for four weeks provide a mass of data about the movement of the sea throughout an entire

tidal cycle.

Another test is the release of nontoxic colour dyes through treated sewage pipes and other outfalls to the sea, laced with harmless microbes that will survive in the sea for a couple of weeks and allow their movements to be traced.

The third test – the one that makes Professor Kay look like a lobster fisherman – is the use of large floats called drogues, which are fitted with GPS tracking devices.

Four drogues at a time are released offshore from outfalls to send back information about where different sea conditions take them.

Professor Kay says: "Each of the three sets of data is measuring the physical movement of something in the sea. If we are getting the same answers from all three tests, then we know we are getting an accurate picture."

All the data from the tests is given to a Hampshire-based company called Metoc, which is building a sophisticated computer model to show what happens to discharges from the Yorkshire coast in all tidal and weather conditions.

Metoc's Richard Dannatt has spent much of the summer in Yorkshire liaising with Professor Kay. The computer model, he says, will provide people like Yorkshire Water, the Environment Agency and local councils with reliable day-to-day information on how to manage the bathing beaches.

For example, results obtained by the tests show that changes in rainfall and tidal movements can affect the way discharges through sewage outfalls or polluted streams move in the sea. This can provide early warning that a particular beach might experience raised levels of bacteria and be considered unsafe for bathing for a day.

Richard says: "Our computer model allows us to run tens of thousands of different scenarios for the Yorkshire coast, with all kinds of tidal states, all sorts of discharges into the sea, and winds of different strength if we want to. What we're trying to achieve is an understanding of the impact on bathing beaches of almost any kind of environmental conditions you can imagine."

One of the biggest factors in the computer model is the impact of rainfall, which exacerbates the flushing of land drainage into the sea and raises levels of bacteria. This is particularly important, because while millions are spent on treating sewage, the agricultural source of potentially harmful bacteria is now recognised as one that needs addressing.

"A sheep deposits almost 10 times more bacteria per day than a person," says Professor Kay. While almost all the human waste is treated, the environmental loading of 100 sheep commonly exceeds that of a million people."

In future, watercourses may require fenced-off buffers to keep stock away. A trial by the Department for the Environment Food and Rural Affairs of "catchment sensitive farming" measures is underway at several sites in England.

The data now being obtained off the coast will provide Yorkshire Water with early warnings of potential pollution events, allowing the company to manage flows into the sea through rivers and streams and decide how to control its discharges, perhaps with more storage at treatment works or more use of ultra-violet lamps to kill bacteria.

The company's bathing water strategy manager, Lee Pitcher, says: "If you go back several decades, everything was sent out through sewage outfalls into the North Sea. Those outfalls have been extended, and the discharges are more and more filtered and treated. The next, exciting, stage is understanding how that waste water disperses, to ensure we have the best bathing beaches we possibly can."

CW 30/10/10