During the past year the Solent Protection Society (SPS) has been investigating the impact of pollution on the Solent. This is a huge subject covering everything from shipping to plastic, sewerage to chemicals, noise to pleasure craft disturbance. We have looked particularly at how pollution gets into the Solent and what action is being taken by the various agencies involved. This has also meant looking at what comes down the rivers and out of the many outfall pipes that discharge into Solent waters.
Water Quality
We are all familiar with beach water quality monitoring by the Environment Agency (EA) which is the prime government body charged with checking water quality round our shores and in rivers. These reports, usually available weekly online (except in this Covid year where they started late and are monthly at present), are produced between May and September. The beaches are not monitored at other times and there are large stretches of the Solent where there are no designated bathing beaches; the western Solent for example. Here some monitoring is done by the EA but the results are usually contained in annual reports published retrospectively. They do however give a guide to trends. England’s rivers, lakes and coastal waters are as polluted as they were four years ago, with only 16 per cent achieving good ecological status, according to government data published in September.
Drainage Systems
Combined Sewer Outfalls (CSOs) are largely part of the sewerage system controlled by Southern Water though some may be private. There are hundreds of these CSOs around
the Solent. Most of the drainage systems in the Solent area are combined systems, that is sewerage water and rainfall flow through the same pipe. Consequently when there is a
discharge, say during a storm or if there is a malfunction, then diluted sewerage comes straight into the river or sea causing pollution. As summer storms have increased, this has been happening more frequently and may on occasions breach the legal limits on the number of times this is allowed. Many of these outfalls are not monitored. Southern Water monitors the main ones and has to report on discharges which are picked up in annual reports by EA. We still await the Water Company Performance reports for 2019.
The main culprits are increased levels of nitrogen and phosphorous, with nitrates in particular enriching the water too much causing green algae blooms. These starve the water of oxygen with the inevitable knock on effect on marine life and plants. Not only does this pollution come from sewerage but even greater amounts come from current and historic fertilizer use on farmland and other sources, all of which eventually washes into watercourses. According to reports commissioned by the Solent area local authorities, the bulk of the nitrate content of the Solent waters comes from unspecified ‘coastal background sources’. While much of that background will be from natural sources, we suspect that a significant proportion is likely to emanate from the long sea outfalls which discharge into the Solent. In the case of Langstone Harbour, we understand that it takes eleven tidal cycles to completely flush and with the overall flow of water eastbound through the Solent relatively slow, much of the material dispersed from these outfalls will remain in Solent waters for many days, moving backwards and forwards as it slowly disperses on the tide.
Nitrate Neutrality
House building in the Solent area has been on hold for most of the year while councils look for ways to make new development ‘nutrient neutral’. Natural England produced guidance in June for how new developments could theoretically achieve “nitrate neutrality”. It does not, of course, do anything to improve an already bad situation but it is better than nothing.
We remain seriously concerned about the volume of new housing proposed. The direction set by the new white paper on Planning for the Future, currently under consultation, suggests that house building in the Solent area will both increase and accelerate. Without significant upgrades to the waste water treatment network and the adoption of sustainable drainage systems on new developments, the risk of unconsented storm discharges from outfalls will only increase.
Addressing the Nitrate Pollution Issue
There are a number of potential options identified this year.
- Acquire farmland in a river catchment area and take lower lying fields out of agriculture and ‘re-wild’ it. This method has been championed by the Hampshire and Isle of Wight Wildlife Trust (HIWWT) who have already used a government loan to acquire a farm on the Island. This will be taken out of production to generate “nitrate credits” which HIWWT can sell on to developers to offset the nitrate produced by their development. The profit made will enable HIWWT to pay back the loan and generate funds for the charity.
- Increase the capacity and efficiency of the wastewater treatment network, improving the capability for handling peak storm water discharge events.
- Continue to improve farming methods to reduce nitrate runoff. Over recent decades the farming industry has made significant progress in improving the sustainable use of fertilisers on farms and it is likely that much of the farm sourced nitrate load entering the Solent is historical. The nitrates being released into the ground from agricultural land take years or decades to finally leach through into the watercourses.
- Strengthen Planning policy to ensure that more areas are protected and that building of housing is more tightly controlled with infrastructure contributions increased to assist with the improvement of CSOs.
- Increase the mud flats and sub-sea plants like sea grass which, along with oysters, are proven absorbers of marine pollution, by vigorously protecting and perhaps expanding the marine protected areas around the Solent coast.
This is an extremely complex issue both legally, environmentally and technically, and there are certainly no quick and/or simple solutions. Each of the above options will play a part, but more effort and investment is needed if we are to turn neutrality into a positive decline. Some of this will require further legislation by government and some of it will inevitably mean increased water bills.
The ‘rewilding’ of farmland to generate nitrate credits has already been used by Fareham and Havant Borough Councils to kick start new housing development and in September 2020, the UK government approved the investment of £3.9 million to set up a first-of-its-kind national online ‘nitrate trading’ auction platform. This is a worrying development since SPS believes that any mitigation actions for housing development around the Solent should be taken for the benefit of the local area.
While the objective of ‘re-wilding’ farmland is admirable, the benefits are unlikely to be seen in our lifetime. What we will see, however, is the impact of the additional development which the ‘nitrate credit’ approach will now permit. The problem for the Solent and its wildlife will get worse, not better, for the foreseeable future.
What actions can SPS take?
SPS has limited resources but we can continue to monitor the reports that are produced by the various agencies and apply pressure where we find objectives are not being met.
We can press for further legislation along with the many other specialist conservation groups who share the same goals.
We will try during the coming year to draw our monitoring into a form which illustrates the trends we find around our precious Solent.
Solent Protection Society 