AN agreement has been struck to try to save the declining Rivers Test and Itchen two of the finest chalkstreams in the country.

In a unique deal, the Environment Agency and Salmon & Trout Conservation UK charity have agreed key environmental local targets for the two rivers to help drive ecological improvements.

The targets are set around the number of key water invertebrates - that should be expected in a three-minute kick-sweep sample.

The targets are for the rivers to support at least 10 separate mayfly species and 500 freshwater shrimps known as Gammarus, in the middle and lower reaches of the catchment. Targets for the upper reaches are still being developed.

The targets, supported by independent evidence and agency data, are one major result to come from the charity's riverfly research which showed a decline in river life, partly caused by contaminants such as phosphates from farmland.

River flies play a vital role in a river’s food chain - lose them, and other aquatic wildlife will follow. Water invertebrates matter for fish, mammals and birds.

S&TC UK is fighting to stop a downward trend in the water life of the chalkstreams. Its national Riverfly Census data has showed that fine sediments and excessive phosphate nutrient are especially damaging to mayfly species, and while Gammarus are also susceptible, they are particularly sensitive to a whole host of other contaminants.

The EA routinely monitor chemical water quality and river ecology as indicators of river health. These new local bespoke mayfly and Gammarus targets will now feature in the way the Environment Agency monitors the health of the Test and Itchen.

Nick Measham, S&TCUK’s freshwater campaigns officer, said: "This could and should mark a major step forward in the way we manage our rivers in the future for the benefit of aquatic invertebrates, fish and the many birds and mammals that depend on clean rivers to survive. S&TC UK will seek to establish similar targets for the other 18 rivers currently in the riverfly census by working to agree bespoke river targets with the relevant local Environment Agency scientists.

“This development is very important. The agency has recognised that our species-level data analysis is an extremely accurate way to monitor the health of a river and we are delighted that the agency in Hampshire has developed and agreed these targets. Understanding why and to what extent riverfly numbers are declining is the first step in the process of safeguarding the aquatic environment – and this is the first time this first step has been taken.”

Mike O’Neill, environment manager for the Agency in Hampshire, said: “Working in partnership with S&TC UK, using the latest research and pooling our data and expertise has been a valuable process. Developing local bespoke targets for mayfly and Gammarus on the Test and Itchen enhances our ability to protect these sensitive chalk rivers, now and in the future. These species are important to the river ecology in their own right, but are also important indicators to river health. Ensuring that these keystone species remain abundant is a vital part of the wider work being carried out on these rivers to ensure that water quality and quantity are improved, for people and wildlife."

S&TC UK’s Head of Science, Dr Janina Gray, said, “While our recent analysis painted a generally worrying picture on the health of mayfly and Gammarus populations, we have now identified and agreed a simple scientifically credible benchmarking figure for invertebrates in a healthy river. Once we have a standard for all rivers along the lines of the local bespoke Test and Itchen agreement, we can help local river managers to develop solutions and so restore our waterways to their former glory.

Paul Knight, S&TC UK’s CEO, said, “Our research is the first of its kind to give such a microscopic picture of the health of our river systems. We are delighted that the Environment Agency in Hampshire is leading the way in recognising the benefits of this detailed sampling and analysis and we hope that it will be a catalyst for their colleagues across the country to take up the cause and so provide the background scientific evidence which points to solutions that will lead to cleaner, healthier rivers for the benefit of all aquatic wildlife.”