The River Arle, for which Alresford is named after starts in Bishop's Sutton, its' headwaters in the pasture field beyond Hobbs Close and out towards the Ropley Roundabout.

It then passes through the Ford in Water Lane, under the bridge at Bighton Lane and onto Alresford Pond, where it joins the Candover Brook and the Cheriton Stream to form the River Itchen at Ovington.

As a chalk stream, the Upper Itchen Catchment is a priceless natural resource, supporting unique wildlife and sustaining businesses such as watercress and fisheries.

There are only around 210 chalk streams in the world, and 85% of them are in the UK, with a good number in Hampshire. They are an important habitat for wildlife, are fragile and suffer from change very easily.

Key for a chalk stream is that it is not primarily fed from other rivers or from the surrounding hillside, but from the chalk underneath the soil. The chalk is made of up the calcified remains of trillions of microplankton as they died, dropped to the sea bed (when this part of Britain was a shallow sea) and built up over millions of years. Highly porous, the chalk acts as an aquifer and a filter to hold water and chalk streams get their water up from the chalk - which is why it is often very pure and without silt.

Some chalk streams do not run all year round, and this includes our one: the actual permanent water table limit is below the stream bed. Large amounts of rainfall during wet seasons do not affect the stream until a number of weeks or months later as the water gradually filters through the chalk and temporarily raises the water level.

This is called a Winterbourne - a wet winter and spring provides the increased water level that the stream enjoys during the summer. We sometimes see the stream dry up at the Ford during the Autumn if there has been a particularly dry summer, until the next wet set of events eventually filters through again.

Chalk streams, with their fast flowing, clean silt-free habitats are perfect for hosting wildlife and flora - the streams are cool and clear, oxygenated, mineralised with a slightly alkaline acidity and will have a consistent flow (apart from the Winterbourne sections, which may dry up seasonally but return to provide the wet habitat)

These environments are home to a surprisingly large variety of wildlife - geese, herons, swans, egrets, moorhens, bats, otters, water voles, crayfish, fish and a whole variety of aquatic insects for them to feed on - upwings, mayflies, olives, freshwater shrimps, Caddis, stoneflies. Many of these we see in Bishop's Sutton, others are dwindling or becoming rarer as the habitat comes under pressure from climate change and modernisation.

The chalk stream is a delicately balanced ecosystem, very much vulnerable to outside pressures. These pressures that the stream may face are complex, and not the fault of a single factor but the accumulation of many.

Run-off can be from urban areas, farmland and roads. It can be the result of sudden high rainfalls on roads adjacent to the stream, which washes vehicle paint, engine oil, petrol or diesel and even tyre and brake residue that has landed in the road into the stream (that oily sheen you sometimes see on roads when they are wet - that's this stuff). This pollutes the habitat is small ways that gradually accumulates over successive rainfalls.

Sediment washed from fields enters the stream, which would normally have little or no sediment, upsetting the delicate balance of the fauna that thrive on the clean gravel. Where fertilisers are used in gardens or farmland these too can wash into the stream.

Sedimentation can come from run-off but also from bank erosion that is caused by excessive mowing, pollution, overshading, cattle poaching and sometimes the invasive Signal crayfish burrows (our native crayfish don't actually burrow).

Chalk streams are naturally low energy systems - this is not caused by sedimentation in itself. The issue here is that (as low energy systems) the streams don’t always have the power to wash excess sediment downstream. Furthermore, erosion/sediment can further decrease the ‘energy’ of the flow by making the stream overly wide and shallow. Even healthy chalk streams will have slower-flow sections, and indeed this is crucial for some wildlife species (kingfishers can’t hunt in very fast flows, and water voles tend to avoid them too). The key is that we do not want the whole river system to be slow but a mix with powerful water spaces providing clear, gravelly fast moving water giving shelter for aquatic insects and other life - excessive sedimentation smothers the gravel and the wildlife inhabiting it, leading to the loss of higher fish, bird and aquatic mammals that feed off the insects.

Sewage pollution is a big changer of the ecosystem - whether its an acute event or pollution incident or more low level chronic pollution that is less dramatic but builds up over the longer term.

As our village has no mains drains, we all live with septic tanks. Ultimately, the water from those 160-odd houses goes back into the ground and may carry with it chemicals that are harmful and eventually build up and reach the aquifer, and then the stream. Its not just the 'sewage' aspect, but also the nutrients that come from our washing powders, dishwasher cleaner, shower gels and shampoos - nitrogen and phosphates which can cause sewage fungus, cyanobacteria and algal blooms to grow. Also studies of less obvious things like caffeine, oral contraceptives and ibruprofen indicate that these elements can pass into sewgae and harm wildlife. It is important to maintain septic tanks to reduce the impact and consider less harmful chemicals.

Get involved with monitoring the aquatic invertebrate life in the stream!

The Arle is monitored and surveyed in a number of places on a regular basis and anyone who would like to help is more than welcome to join in this fascinating exercise. This involves taking a sample from the stream bed (waders or long wellies essential! or you may prefer to do your bit on dry land) using a method called 'kick-sweep', heading back to the riverbank and then identifying and counting what you have found.

People who are interested in riverfly monitoring can contact us at the Wildlife Trust as we can provide training and equipment and a session can be arranged where you can watch the samples being taken and see the streams' invertebrates up close.

for more information, email ian.diver@talktalk.net

There is a large variety of invertebrates in the stream, the numbers of which can tell us a lot about the water quality, oxygen levels, pollutants, and so on. this is includes all manner of the Mayfly and Olives family, freshwater shrimps, Caddis (cased and uncased) and stoneflies. These form the basis of the food chain, and the more that there are, the more likely we will be to see larger fish, birds, mammals and bats that feed off them.

for more information, contact winterbournes@hiwwt.org.uk

Walk the stream banks, and look for places where Brown Trout have made their nests - known as 'Redds'. Record the size, number and location of these spawning sites.

Training is provided for what to look out for, and you can help support this iconic species by monitoring their populations.

For more information, contact People who are interested in riverfly monitoring can contact us at the Wildlife Trust as we can provide training and equipment and a session can be arranged where you can watch the samples being taken and see the streams' invertebrates up close.

for more information, email ian.diver@talktalk.net

There is a large variety of invertebrates in the stream, the numbers of which can tell us a lot about the water quality, oxygen levels, pollutants, and so on. this is includes all manner of the Mayfly and Olives family, freshwater shrimps, Caddis (cased and uncased) and stoneflies. These form the basis of the food chain, and the more that there are, the more likely we will be to see larger fish, birds, mammals and bats that feed off them.

for more information, contact winterbournes@hiwwt.org.uk

We all have septic tanks or similar off-mains waste systems in the village. Individually, each tank is a small thing but accumulatively across the village can have a huge impact, especially when not maintained.

Owners do have legal responsibilities but may not be aware of them and there are many ways to manage these systems well and reduce the impact. Check out our pages on septic tanks and how they can be managed to reduce their impact.

Suitable for schools and uniformed groups within our scheme area, Watercress and Winterbournes provide sessions which are free and help is available for transport costs.

There is a wide range of activities for both classrooms and riverbank, such as:

'Source To Sea' journey
Water conservation trail
River dipping
Landscape art
interactive quizzes
model making
achievement badges

For more information, contact People who are interested in riverfly monitoring can contact us at the Wildlife Trust as we can provide training and equipment and a session can be arranged where you can watch the samples being taken and see the streams' invertebrates up close.

for more information, email ian.diver@talktalk.net

There is a large variety of invertebrates in the stream, the numbers of which can tell us a lot about the water quality, oxygen levels, pollutants, and so on. this is includes all manner of the Mayfly and Olives family, freshwater shrimps, Caddis (cased and uncased) and stoneflies. These form the basis of the food chain, and the more that there are, the more likely we will be to see larger fish, birds, mammals and bats that feed off them.

for more information, contact winterbournes@hiwwt.org.uk

Suitable for all ages under 18 (with accompanying adult supervision), the Chalk Stream Challenge can be completed by families, schools, and uniformed groups. This includes a range of fun learning and exploration activities.

There are activity sheets, spotter guides, and certificates free to print at home. There are also fabric badges that can be ordered for a small fee.

For more information, see https://www.hiwwt.org.uk/watercress-and-winterbournes/chalk-stream-challenge

There are grants for landowners with the chalk streams running through their properties (land not in a stewardship scheme or requiring work not covered by one) for up to £5,000 which can be the larger part of the total project costs.

Projects must help to prevent sediment and pollutants from entering the chalk stream or improve its riparian habitat - for example improving yard drainage, improving the treatment of pesticide washings, reducing soil wash caused by vehicle movements, reducing rainwater entering and running off manure, slurry and silage stores, reducing the impact of cattle poaching at stock gathering areas, gateways and riverbanks and reducing the impact of tracks acting as routes for sediment to enter water courses.

For more information, contact winterbournes@hiwwt.org.uk

The village is completely off-mains for its sewage waste, each of us owning or sharing a septic system. This waste undergoes a natural separation of solids and liquids due to gravity, and is increased by bacteria performing both aerobic (oxygen-based) and anaerobic (non-oxygen based) digestion. The bacteria use up some of the waste as they grow and reproduce.

These septic systems are healthiest when teaming with bacteria and in a healthy tank the draining water will be fairly free of solid contaminants but will still contain chemicals from our domestic waste which have a negative effect on aquatic life.

A closed system (far above) is commonly called a Cesspit. This is simply a large tank, which when full, needs to be emptied. Nothing discharges into the ground.

A Septic System (above) is made up of two tanks and is the most common type. The first tank settles the majority of the solids, and the water then flows into a second tank to repeat the process before finally discharging out into a gravel soakaway where further filtering and bacterial work is done. Sometimes, the two tanks are separated from each other, with an electric pump from the first to the second - this is called a Micro Pump Station.

More recently, Package Plants are installed (right) - there is a third tank in between the two where air is introduced via a motor, increasing bacterial breakdown to the point where a gravel soakaway is not needed and the water discharges straight into the ground.

Our chalk stream, the Arle itself and further downstream the Itchen waterways are all showing signs of environmental stress caused by chemicals and excessive nutrients, some of which are legacy from decades ago but are now coming out of the ground and also are accumulating from the waste water coming from our own septic tanks.

Water flowing from healthy septic systems contain chemicals and nutrients which can be harmful to aquatic life - small doses is ok, however excessive or faulty systems increase that significantly

This is exacerbated by the factors (above), all of which contribute to the pressures on the natural system.

When tanks are not working properly, they pollute the ground, which eventually ends up in the streams and rivers. Also, many of our day to day chemicals, including medicines, microplastics and cleaning products are known to have a detrimental effect on the flora and fauna.

Sewage pollution is usually chronic and/or accumulative (individual systems each contributing a small amount, times the 160-ish houses in the village), which is harder to spot. This will be exacerbated by low water flows in dry weather or in very wet weather when abstraction levels are high.

This increases the cost of drinking water production, harms wildlife and changes the ecosystem and interferes with our enjoyment.

Algal blooms are the direct result of sewage pollution.

Sewage is rich in nitrates and phosphates which while being natural nutrients, increases many-fold the existing nutrient levels and upsets the delicate balance of the ecosystem. Algae take up these nutrients very quickly and bloom exponentially in range. This in turn blocks out essential sunlight, uses up oxygen and smothers the habitat for other plant and aquatic life.

Phosphate monitoring measures the bioavailable form of phosphorous which is naturally present in small quantities. There is legacy phosphate in the ground and groundwater from past use (but no longer used) of phosphate-rich fertilisers and cleaning products.

Phosphate is the most common cause for English rivers to fail their ecological health statuses. Most phosphates cannot be removed from off-mains septic systems. These are a small contributor nationally but can have a big localised impact, especially in headwater areas like our village.

The monitoring of riverflies and other aquatic insects is a very good indicator of sewage impact.

Their numbers can be affected by algae smothering their eggs. There will be a lower diversity of insects than would be typical for this type of stream and the relative absence of more sensitive species such as the Blue-winged Olive and an increased presence of the more robust water water louse are tell-tale signs.

Survey results for the chalk stream have been below the 'trigger level' where a report is sent to the Environment Agency four times in the past year.

We have a legal responsibility for keeping our systems healthy and can be prosecuted if not. Off- Mains systems are regulated by the General Binding Rules which states:

You must empty your systems regularly according to the recommendations of the manufacturer or specialist wet waste companies who can advise based on size, system type, and number people using it. In many cases, this would be at least once a year. The myth that tanks do no not need to be emptied is just that - a myth - and breaches regulations.

You must service your systems and repair faults so that they are functioning properly.

Systems in certain locations or those with high-volume discharges may need a permit.

It is illegal for septic systems to drain directly into a water course

In all cases the bottom line is that discharges must not cause pollution.

For a full version of the rules, please visit https://www.gov.uk/permits-you-need-for-septic-tanks

We live here, and all have a part to play in the health of our stream and the surrounding countryside, whether it's maintaining our septic tanks so that they don't pollute, or reducing the harmful chemicals that we put down our sinks, washing machines, dishwashers and toilets.

Individually, we can do small things which don't make a huge difference to us personally but collectively help our immediate environment - it may be swapping out cleaners for more environmentally-friendly ones that do the same job, or just reducing the amount we actually put in the first place - it all helps.

Ensure that your septic system is emptied and maintained by a specialist company and keep your system in good condition.

Do not block your system up with fat (fat and cooking oils should be put in jars and disposed of in your refuse bins), food waste, nappies, cat litter or wet wipes (even flushable ones) - if you have a pump it only takes one wet wipe to clog the impeller and cause an expensive replacement.

disinfectants, antibacterial products, pesticides, bleach and caustic soda will kill the good bacteria in your septic system - look for alternatives (eg. use normal soap bars instead of antibacterial liquid soap). Phosphates are found in cleaning products - There are some very good washing products which are much less harmful - for example
Check out the Ethical Superstore for a whole range of products at https://www.ethicalsuperstore.com/category/cleaning-and-household/

Dispose of paint, chemicals etc at the Council recycling site - do not put them down your drain. A handy link at the County Council on what you can dispose of and where locally is here: https://www.hants.gov.uk/wasteandrecycling/whattodowithwaste

Do not put too much water down your drain all at once - washing machine, dishwasher, baths all emptying at the same time) as this can overwhelm the system and not give it time to separate the solids out. Do not drain rain water from your roofs directly in your system