Tag Archives: diffuse pollution

Better farming practices to help our rivers

The new Farming Rules for Water

From April this year farmers across the country will be following a new set of guidelines that allow them to manage their land in a way that has benefits for them as well as for our rivers, lakes and coastal waters. We welcome this step by the Department for Environment and Rural Affairs (Defra) which will encourage farmers to think about water pollution and the positive steps they can take to reduce their impacts on our wonderful rivers – you can’t turn your nose up at that!

Water pollution is a big issue for rivers, and modern agricultural practices unfortunately play a big part in degrading water quality, especially in rural areas across this green and pleasant land. The manure and manufactured fertilisers that farmers add to their land contain vital nutrients like nitrogen and phosphorus that plants need to help them grow healthily.  But when it rains, these nutrients can easily be carried away from the fields, and drain into rivers and other nearby waterbodies. This is called diffuse water pollution, and agriculture is responsible for about a third of the diffuse water pollution in the UK. Although individual incidents may only have a small impact, collectively they can be very damaging. Lakes, rivers and streams cover only 2% of the landscape but the composition of their water reflects the combination of every activity taking place in the area of land they drain (their catchment). These accumulated nutrient levels cause fast growing algae to boom, smothering wildlife and damaging these sensitive ecosystems.

Topsoil is also a valuable resource for farmers because this is where plants lay down their roots. A nice thick layer of good quality topsoil will contain all the nutrients that plants need to survive. Grass provides a great source of food for many farm animals and its roots help to bind the nutrient-rich topsoil together to stop it washing away. As livestock walks across the grass, the animals’ feet can cause damage to the turf, especially in wet and muddy conditions. This is called ‘poaching’ and can increase soil erosion, causing our rivers to run brown after rainfall, which affects the fish and insects which live in them.

Defra’s new Farming Rules for Water will help with these problems:

Farmers must test the soil in their fields every 5 years for nutrients like phosphorus and nitrogen. This allows them to better plan how much fertiliser they need to add to make sure the needs of their crops are met but not exceeded; saving them money and improving water quality in the process.

Fertilisers must be stored in a way that doesn’t pose a significant risk of pollution, and they shouldn’t be applied close to rivers and other waterbodies. By not spreading fertilisers on waterlogged or frozen ground, farmers can increase the rate of retention in their fields and less of the nutrients will be washed away.

Reasonable precautions must be taken to reduce soil erosion, and livestock feeders should be positioned away from rivers, lakes and springs. Any land within 5 metres of fresh or coastal waters will have to be protected from soil erosion by preventing poaching by livestock.

A full list of the rules can be found here: https://www.gov.uk/government/publications/farming-rules-for-water-from-april-2018/farming-rules-for-water-overview

Most farmers will already be doing these things through their current farming practices, but these rules will bring all farms up to this higher standard so that everyone is on a level playing field. Steps like these are really positive and will help British farmers be more profitable and be more aware of their potential impacts on the environment, which in turn will help our rivers.

A new, exciting project to improve water quality on the Beverley Brook

So you know that the roads can be pretty dirty. You see the direct effects of it on your car when you think it’s probably time to give it a clean. The dirt on the roads is also really well illustrated when it snows and soon the pure white snow changes to black slush. But where does all of this dirt come from?

You see trucks and lorries leaking oil and busses belching out thick clouds of exhaust fumes when pulling away from traffic lights. You see gulley pots full of litter, cigarette butts and sand that has run off the nearest building site. Or the paint that is dripped out of vans or has been poured into the curb. You walk along the street dodging ‘dog eggs’ which litter the pavement. Then in winter the roads get spread with grit and salt during cold snaps.

You may consider of all of these things as unsightly or unpleasant when on the roads, but within a short period of time and with a bit of rain, all of these substances are washed away and are out of sight and out of mind. But where does it disappear to?

The answer: often the nearest watercourse.

The initial runoff, known as the ‘first flush’, runs black especially in urban areas. In turn with many other outfalls also discharging the entire river turns black.

First flush on the River Wandle, South East Rivers Trust

So what is in this run-off?

Basically it consists of a nasty cocktail containing pieces of the road surface, tyres, brake pads and other material from engine parts from regular wear. Throw into the mix some fuel, gear oil, grease, brake fluid and antifreeze. Then for good measure add some pesticides, fertilisers, plant detritus, some illicit dumping of substances, inputs from misconnected drains and in winter de-icing grit and salt.

Unsurprisingly road runoff can be detrimental to the receiving watercourse, whose impacts on riverine ecology can be acute or chronic. The sediment smothers gravels vital for invertebrates and fish. The turbid water reduces light penetration so plant communities suffer due to limited photosynthesis. Furthermore, the sediment blocks the feeding mechanisms of filter feeders and gills of other aquatic organisms.

The Poly Aromatic Hydrocarbons (PAHs) (oils) and heavy metals are both known to be toxic to aquatic fauna. High concentrations of heavy metals associated with the ‘first flush’ can ‘shock’ aquatic environments as the water is polluted with levels several times higher the normal concentration. Multiple studies have shown that heavy metals can also cause long term impacts as they bio-accumulate within the food chain.

So what can we do?

It is well known that these contaminants freely bind to sediment. It therefore follows that if the sediment is removed, so too will many of the contaminants. This is the plan to protect the Beverley Brook in Richmond Park.

The Project

The Rivers Trust and WWF are managing three water management projects in the Thames and South East River Basins, for the benefit of both people and wildlife. The wider initiative is funded by the Coca-Cola Foundation and contributes to Coca-Cola’s promise to safely return the full amount of water used in finished beverages and their production to communities and nature by 2020 – an ongoing commitment as they managed to reach this goal five years ahead of target. Globally Coca-Cola works in over 2000 communities and supports more than 248 community water partnership projects in over 71 countries – this being one of them.

A schematic of how a Downstream Defender works

We are delighted to announce that the South East Rivers Trust is delivering one of these three projects which will see a large (and I mean very large) silt trap, known as a Downstream Defender® supplied by Hydro International, installed onto a surface water drain. The drain currently carries run-off from the incredibly urban surrounding catchment directly into the Beverley Brook. The Downstream Defender will trap a large portion of the sediment and associated contaminants, preventing them from reaching the Beverley Brook. Intermittently the trap will be emptied with a gulley sucker and the toxic sludge removed to landfill. Consequently, the health of the river will improve making it a better place for both wildlife and people.

Last Tuesday we launched this collaborative project with the arrival of the Downstream Defender to Richmond Park. We’d like to thank our funders, the Coca-Cola Foundation, as well as all our partners including WWF, The Rivers Trust, the Environment Agency, The Royal Parks, the Friends of Richmond Park and Thames Water. Also a big thank you to Hydro International for supplying the Downstream Defender and for their much appreciated contributions to the launch event. Thank you to all the guys at Kenward Groundworks; Tony, Matt, Dave, Mark and Woody for all your efforts with installing the chamber. And finally thanks to John Sutton from Clearwater Photography for taking photograph of the launch and project.

Partners with the Downstream Defender Silt Trap


Celebrating the launch of the project with partners and volunteers

Photos: John Sutton, Clearwater Photography


Hogsmill Newsletter: May Edition

The latest edition of the Hogsmill Newsletter is now available to download. It summarises the results of River Monitoring Initiative (RMI) sampling together with other pollution monitoring and activities and events along the river.

Hogsmill Newsletter May 2017

If you have any comments or suggestions about the newsletter please contact:  Peter Short: rpetershort@hotmail.com

Keep up to date with the Hogsmill


There is a new newsletter for anyone interested in or involved with the health of the Hogsmill. It summarises the results of River Monitoring Initiative (RMI) sampling together with other pollution monitoring and activities and events along the river.

Hogsmill Newsletter March 2017

If you have any comments or suggestions about the newsletter please contact:  Peter Short: rpetershort@hotmail.com

Water quality improvements are on par at Richmond Park

Shortly I will post another blog updating you on how the river improvement works in Richmond Park are settling in one year after they were completed. Although the river habitat works have been completed (for now!) work has by no means ended. In addition to improving the habitat, our attention is also focused on addressing the poor water quality entering into the Brook.

Upstream of the Richmond Park golf course, rain water pours off the surrounding urban catchment and notably down the incredibly busy and often choked A3 at Roehampton Hill. It then flows down the gulley pots, into a surface water drain before this opens out into a ditch which flows across Richmond Park Golf Course before discharging into the Beverley Brook. Such road runoff is known to cause detrimental effects to the aquatic environment, not only from the significant quantities of sediment carried in it, but additionally from the contaminants bound to it. These include Poly Aromatic Hydrocarbons (PAHs), hydrocarbons and heavy metals. Our aim was to therefore capture the sediment and the contaminants before they reach the Brook. This was achieved with a two pronged attack.


Oil from the A3 covering the surface of the pond in the golf course. Thick black sediment covers the bed

First of all, mid-fairway at the upstream end of the golf course we opened the ditch out to create an on-line pond, known to us as a silt trap but to golfers as a feature water hazard. With help from Rob McInnes, the pond’s size was calculated so that all coarse sediment down to 0.1mm would drop out as a consequence of lowering the velocity of the flow. A shallow marginal ledge was incorporated along the length of the pond, which has been planted with a mix of wetland plant species to promote deposition, whilst providing species and habitat diversity. By emptying the pond regularly, the silt is removed from the system and the effectiveness of the trap is maintained.


Starting to open the ditch out


A few months after completion, the pond is trapping plenty of silt (and plenty of golf balls)

The second measure took place a few hundred metres further down the ditch where an existing online pond, in the shape of a ring doughnut, provided an excellent opportunity to be modified to create a wetland. The plan was to re-jig it so that the doughnut became a U-shape. This prevents short-circuiting, therefore increasing retention times, reducing velocities and again promoting a depositional environment.


The pond before works start

The pond was too deep to plant straight into, so we needed to find spoil to fill it in. What better way to produce the spoil than dig a second wetland immediately upstream of the first, which will increase the treatment capacity further.


Re configuring and filling in of the pond

Six thousand plants consisting of over 20 species were planted in the wetlands. The dense structure created by the plants results in even finer sediments being captured than in the silt trap upstream.


The wetlands newly planted with 6000 plugs and fenced off


August and the plants have established

Furthermore, this has now created a fantastic wetland habitat full of dragonflies, damselflies and frogs to name a few. Both the silt trap and wetlands have been fenced off and have bird twine strung over them to prevent the large population of geese from nobbling the plants before they had the chance to establish. The total area of both is approximately 800 metres square.

A simple water level control structure was created at the outlet of each wetland. As sediment accumulates and reduces the depth of water over time, another drop board can be put in, allowing the water depth to be increased, therefore reducing maintenance requirements and prolonging the life of the wetland.

The effectiveness of the installed measures is currently being monitored, however a coincidental site visit during a pollution event helped to anecdotally demonstrate the effectiveness. Run-off from a presumed building site was bringing significant quantities of sand rich water into the ditch. After the silt trap, the turbidity of water flowing out was visually improved. Walking further down the ditch network, after flowing through both wetlands, we were incredibly impressed to see that the water flowing out and into the river was clear to the eye. Although this was always the theory behind why we created these features, to see it work first hand to such a great effect was brilliant and hugely satisfying. With contaminants generally being bound to sediment, this clearly demonstrates not only a reduction of sediment input to the river but indirectly of contaminants too.


Thick sandy water flowing into the sediment trap


Water in the ditch downstream of the sediment trap and both wetlands


Significantly improved water clarity entering into the Beverley Brook

Job done!! (for now anyway). I am now working up the next phase of water quality improvements. Updates will follow shortly.

As always, the success of this project is down to the valuable contribution of many people and organisations.

Big thanks to the ongoing project partners; the Environment Agency, Defra, The Royal Parks and Friends of Richmond Park. Thanks to Jon Dummett and Gary Stewart at Glendale Golf Course for surprisingly being so willing in allowing us to dig up their course and for their continued support since. Thanks to Rob McInnes at RM Wetlands & Environment Ltd for guiding the designs, Ben and the guys at Aquamaintain for braving the cold February days delivering the work and again for planting it up. Thanks to Thames Water for providing the flow meter which was installed in the ditch network to inform the design and finally, to Layla at Queen Mary University for monitoring the work.

Outfall Safari on the Hogsmill

ZSL and the Hogsmill Partnership are looking for volunteers to help us map polluted outfalls on the Hogsmill this October.

While walking the Hogsmill you may have noticed all the different pipes that can be found along the river bank. These pipes are usually part of our surface water infrastructure, transporting clean water from our roads and roofs into the river. However in some cases, these pipes or outfalls can be polluting the Hogsmill as they have been misconnected.

Polluted Outfall

Misconnections are a BIG issue for urban rivers and the Hogsmill Catchment Partnership have been working hard to start addressing this on the Hogsmill River.

A misconnection is when a toilet or washing machine has been connected to the surface water drain heading straight to the river, instead of the sewer system. You can read more about misconnections at on the Connect Right website.

Connect Right

This October, ZSL are running an Outfall Safari to map all these pipes heading into the Hogsmill, and assessing their condition to check for misconnections.

Volunteers will receive training on how to recognise signs of pollution at these outfalls and record the pipes on a new smartphone app. This survey data will greatly improve our understanding of the river system and help to target sources of pollution.


If you would like to join the team, you can sign up on EventBrite to register your interest. Once you’ve registered, more information will be sent to you about where and when the training sessions will take place.

Sign Me Up!

For more information contact by email: Joe.Pecorelli@ZSL.org, or phone: 07974 725 557
Outfall BannerPlease register your interest to help at: hogsmilloutfalls.eventbrite.co.uk

You’ll need to read this before your training session: 2016-Pre-training-information-for-Hogsmill-Outfall-Safari-Volunteers..pdf

New London Partnership Project to tackle Urban Pollution

We have teamed up with Thames 21 on a new project to tackle urban pollution across London’s rivers.

Many improvements in the quality of urban rivers have been made in recent years, but lots of serious water quality issues remain. One of the biggest issues is ‘urban runoff’, where a toxic mixture of contaminants derived from urban areas drain straight into rivers.

With surface water drains often running straight into rivers, these contaminants are washed directly and unfiltered into urban rivers when it rains. During these ‘first flush’ events, river water often changes from being clear and colourless to being an opaque grey-black colour, and water analysis shows that a complex mixture of hydrocarbons, fine particles, nutrients, microorganisms and heavy metals are the cause.

First Flush samples from the River Wandle

First Flush samples from the River Wandle

In urban areas the contaminants causing rivers to run grey-black in colour may have a greater impact, but the locations at which they enter a river are often unknown, and they are relatively costly to survey, with samples needing to be processed by a lab.

Our project with Thames 21 is testing a low-cost sampling method that can be used by volunteers to identify complex urban contamination. In particular, it aims to investigate Surface Water Outfalls (SWOs) which discharge contaminated urban runoff into London’s tributaries of the River Thames.

The method being developed is based on evidence from data collected on the River Wandle, and urban sites in Wigan in NW England, which show that Total Suspended Solids (TSS) are strongly correlated with several important heavy metals and E. coli (a bacterium which can indicate faecal matter) and can therefore be used as a low-cost proxy to identify problematic concentrations of these contaminants.

The next step in this project is for us and Thames 21 to create Pollutant Profiles for our rivers to see if they match this correlation. You can follow progress on the project on our Twitter feed @SE_Rivers_Trust with #TSS!

Restoration to the Beverley Brook in Richmond Park (Phase 1)

The write up of the introduction to the project can be viewed here.

I have now returned from being out at Richmond Park delivering the first phase of restoration to the Beverley Brook in Richmond Park. It has been a while and lots has happened which I am keen to share. I suggest you make a cuppa, take a seat and get comfy.

The Beverley Brook possesses incredibly flashy characteristics due to the urban nature of the river with a significant proportion of the catchment being coated in hard, impermeable paving. With the plan to be on-site for seven weeks through the British autumn undertaking a significant amount of in-channel works to 600 m of river, we were firmly in the hands of the weather once again.

The aim of the project is to enhance the heavily degraded, uniform and generally inhospitable channel so that it would be more inviting to the native fauna and flora that should be present and abundant.

A sorry state at the start of the project

A sorry state at the start of the project

Before the works started we undertook a range of monitoring to capture the baseline condition of the river. These will be vital and incredibly interesting to refer to in the years to come to demonstrate the effectiveness of the project. The monitoring included a two day fish survey undertaken by the Environment Agency, habitat mapping, aquatic invertebrate and plant surveys, sediment analysis and novelly for us, a drone recorded aerial video and photography of the site with some exciting low fly-over manoeuvres.

Drone in Action

Drone action

The work then commenced. With the help from the Aquamaintain guys once again and with Trevor behind the controls of the long reach excavator, we set about spicing up the bland channel. The key to this was variety. A variety of flow types, a variety of channel widths, depths and bank profiles. By adding diversity, a mosaic of habits would be created, providing for  a range of species throughout their life stages.

When discussions about the project first started with the Royal Parks a year or so ago, I could not believe my ears when they announced that there was no shortage of trees and rootwads we could source from the Park to use in the river. With this rare offer, I was like a kid in a sweet shop. With the help of Mick Baker, the Park’s go to forester, dozens and dozens of oak trees were felled (I must add this is as part of the Park’s management regime), the root balls dug up and all carried down to the river by the mighty forwarder (tractor).

Rootwads and LWM ready to be used

Rootwads and LWM ready to be used

Some of the LWM stockpile seen from the air

Some of the LWM stockpile seen from the air

Mick bringing down another load of oak tree tops

Mick bringing down another load of oak tree tops

The wood was introduced to the river in a variety of methods to perform a number of tasks. In places, masses of the tree tops and smaller limbs were stacked up against the bank extending between a third to half way across the channel. These were compacted with the huge force of the excavator and then secured with posts and fencing wire. This technique reduces the channel width to give the river more energy whilst providing complex habitat both above and below the water line. Furthermore, the dense network of branches creates slack water, encouraging silt to drop out whilst also capturing leaves and seeds. Overtime, these structures will consolidate and vegetate to form a new bank. By alternating the bank these are constructed on, a meandering sequence is created in conjunction with the next method, backfilled faggots.

Tree tops and brash in the foreground before being compressed and secured

Tree tops and brash in the foreground before being compressed and secured

Faggots (brash bundles) are fixed to the bed with posts and wire to create the new bank line, again reducing the channel width in places from 7 metres down to 2.5. The steep banks are then regraded and the spoil placed behind the faggots to produce low lying berms which in time will become wetlands when marginal plants establish.

Faggots with incorporated LWM being used to narrow the over-wide channel

Faggots with incorporated LWM being used to narrow the over-wide channel before being backfilled with the regraded banks

Protruding out of the tree tops and faggot berms, larger tree trunks, rootwads and multi-limbs (Large Woody Material, LWM) where fixed into place, extending out across the channel.

Rootwads providing complex cover

Rootwads providing complex cover with a backfilled faggot berm behind

Doing so is a great way to not only provide complex cover but is also a way to reinstate energy back to the river. As water rushes over, under and past the structures, the bed is scoured, creating deeper holes and throwing up the cleaned gravels into shoals and bars. This is a truly rewarding aspect of the work, identifying where and how to place the wood. Even under low flows, the impact can be felt immediately with the gravels being kicked up around your feet. A day later, the bed downstream is glowing with gravels as opposed to the previous uniform blanket covering of sand. And again, after higher flows, features are carved out and created.

LWM immediatley forming holes, shoals and riffles

LWM immediatley forming holes, shoals and riffles

The banks were also naturalised as we progressed downstream. The steep gradient was reduced where possible to provide transitional areas between the terrestrial and aquatic habitats. Intermittently, hugely over-engineered concrete headwalls with tiny two inch blocked land drains poking out scared the bank. Being redundant, these were removed with a total of 20 tonnes of concrete being mucked-away from site.

Another concrete headwall being removed

Another concrete headwall being removed

Significant regrading of the perched banks to form a wide wetland area on an inside meander, soon to be planted

Significant regrading of the perched banks to form a wide wetland area on an inside meander, soon to be planted

A key aspect of the project is to restrict deer access to the channel. To do this the entire 600m length which is divided into two sections was fenced off. However, to prevent them accessing the stretches by simply walking up the channel, we had to construct river gates at the ends of the sections. In a river as deeply incised and flashy as the Beverley Brook is here, this took some doing. We ordered in several chunky telegraph poles. Some were cut and notched to form half jointed A-frames. These were positioned in deep holes high up on the banks. Mounted onto these, the excavator lifted 12 metre telegraph poles to span the channel. From these using stainless steel eye bolts and chains, oak gates from wood sourced and milled in the Park and manufactured by our good friend, Norm Fairey were hung. The principle being that the river gates prevent deer passing but importantly not causing a debris build up.

A section of the 600m of fencing which has been erected

A section of the 600m of fencing which has been erected

The moment of truth, the telegraph pole spans the 12m gap before the braces are removed from the A-frames and the holes are filled with concrete

The moment of truth, the telegraph pole spans the 12m gap before the braces are removed from the A-frames and the holes are filled with concrete

Jack standing back and admiring one of the three telegraph pole river gates completed

Jack standing back and admiring one of the three telegraph pole river gates completed

A conveniently placed bridge provides the structure for the fourth set of gates

A conveniently placed bridge provides the structure for the fourth set of gates

The last task was to create a deer and dog access point. These access points prevent the banks being eroded (poached) with the subsequent input of sediment to the channel. The banks were regraded to a shallower angle and first armoured with 20 tonnes of gabion stone and then covered with compacted scalpings.

Access point in the foreground with the most downstream river gates behind marking the end of the restored section or river

Access point in the foreground with the most downstream river gates behind marking the end of the restored section or river

As I mentioned at the beginning, we were needing the autumn weather to be kind to us. Who could believe it? Throughout the first three and a half weeks we barely had a drop, allowing great progress with the in-channel works and with ground conditions holding up well. After that, we did lose a couple of days due to rain and the spatey flows but I considered we had been lucky and gratefully accepted it.

The New Year has provided the first heavy flows. I managed to get down to the river yesterday and waded the length inspecting how things are bedding in.  I am pleased to say that the restoration has certainly been successful in the aim of providing variety. With more energy, the river at last has active functioning processes.

Before, blandness!

Before, blandness!

And after, variety is the spice of life!

And after, variety is the spice of life!

The Large Woody Material is scouring holes with loose gravel riffles forming downstream. The bed on outside of the meanders is deepening with large deposits of sediment forming shallow berms on the inside. The tree tops are accumulating sediment and consolidating quickly. The water’s surface is rippled and broken making the river audible once again. Even whilst doing the work, each morning a walk up the river demonstrated the immediate effectiveness with dace and chub taking up residence in new lies and pools where before there were none. I am thoroughly looking forward to seeing how the river adjusts and naturalises over the coming weeks, months and years.

So moving on, next month we start addressing diffuse urban pollution entering into the Brook from the A3 by digging a sediment trap and creating two wetlands. We are also having our first of several planting days. This one introducing trees to the river banks to provide shade and Large Woody Material in the future. We will keep you posted.

There are so many people to thank. The funders; The Friends of Richmond Park, The Royal Parks, the Environment Agency and the Beverley Brook Catchment Partnership. And those that helped out;  Simon, Julia and Adam at The Royal Parks, the guys at Aquamaintain; Ben, Dave, Jack, Zac, Lloyd and Roo. Trevor from Land & Water  in the machine, Norm Fairey, Curling Fencing Contractors, Mick Baker, Andy Birnie, Colin Hampton, Luke and his drone, the list goes on. Thank you all.


Happy Anniversary to the Hogsmill Pollution Patrol

Pollution on the HogsmillWith the start of 2016 comes the One Year Anniversary of our Hogsmill Pollution Patrol scheme – and what an amazing job it has done so far!

Throughout 2015, our trained volunteers have been monitoring 15 outfalls on the Hogsmill for signs of pollution such as misconnected appliances and sewage discharge.

Together they have submitted 470 reports of pollution to us. Working with the Environment Agency and Thames Water, we have been able to start investigating these issues and begin work towards rectifying them to improve water quality on the Hogsmill River.

To read the latest update of our work, please download our Newsletter below.

Pollution Newsletter December 2015

If you see pollution on your river, call the Environment Agency hotline on:

0800 80 70 60


Polluted Outfalls and Riverfly Monitoring

Last week I was lucky enough to visit the Hogsmill River twice with some of our dedicated Pollution Patrol volunteers.

The Team!

From left to right: Geoff, Me (Polly), Steph, Peter, Bill and Jan

Our Pollution Assessment Volunteers (PAVs) work hard to track down and monitor polluted outfalls on the river, sending reports to the Environment Agency for action.

On Wednesday we were joined at a particularly bad outfall by our local Environment Agency Officer Steph to take some samples.

Sewage Fungus

Sewage fungus at the outfall

Steph sampled for ammonia, which is used as an indicator of raw sewage entering the river, and for oxygen available to river invertebrates and fish. Oxygen is a good indicator of how polluted an outfall is, as bacteria use up oxygen to break down organic pollutants, which reduces oxygen available to other species which can sometimes result in fish kills.

Sampling for Oxygen

For this week, both readings were fine.

This is one of many outfalls we’ve been looking at. You can find Steph’s updated report here.

Hogsmill Report July 2015

On Friday I was invited along to the monthly Riverfly Monitoring session at the same outfall with the same dedicated team. Every month they get together at this location and take a kick sample of invertebrates as an indicator of how healthy the area is.

Riverfly Monitoring

Some invertebrates such as caddis flies are very sensitive to pollution and are therefore an excellent indicator of water quality. If this is something you might be interested in, check out the website here!

Thank you to all our volunteers working on the Pollution Patrol scheme – we are making progress!

What have we been up to?

We have had a busy start to 2015 – maybe it is time for you to catch up with what we have been up to?

River Restoration ~ Luke has been busy transforming the Ravensbury Park Back Channel on the River Wandle for both the local community and wildlife. Read all about his progress here.

Pollution Control ~ Olly has been working hard trialling new methods to mitigate against urban diffuse pollution. We have trialled Siltex in Carshalton Ponds and installed Mycofilters at problematic outfalls.

Looking Forward ~ We’ve got restoration projects this year on the Hogsmill and Beverley Brook so keep your eyes peeled for more updates!

The Problem with Urban Duck Ponds

Carshalton PondsIn a highly developed landscape such as Greater London, urban ponds can provide an important haven for wildlife and therefore it is important to keep the waters happy and healthy.

Unfortunately over time urban ponds tend to fill up with sediment washed from the surrounding area such as leaf litter and bird droppings. Have you ever been for a walk along the Wandle to Carshalton? If you have, you will have undoubtedly seen a mass gathering of wildfowl at the ponds. These high densities of geese and ducks can be a particular problem with their droppings increasing the organic content of the ponds, resulting in algae blooms and a deterioration in the water quality.

Birds Birds Birds

So what can we do?

The Wandle Trust are trialling Siltex in Carshalton Ponds as a potential solution to the surplus of silt.


Siltex is a natural chalk-like substance which helps to increase the speed of silt breakdown by stimulating natural processes. It is environmentally friendly and is harmless to plants and animals.

In the next week, we will be applying the Siltex powder to the mud in Carshalton Ponds. The effects of Siltex will then be monitored closely over the next few months by our staff to determine the effectiveness of the measure and its effects on water quality.

We will of course keep you updated with our news – so keep your eyes out for more Siltex blogs.

Pollution-Busting on the Wandle

Over the last 2 years, the Wandle Trust has been intensifying efforts to tackle the considerable problem of pollution in the river. Often contamination can be tackled by our partners in the Environment Agency, tracking down pollution to the source. However, this does not work for all sources of contamination.

For example, contaminants such as particles from car exhaust, the loss of engine oil and other contaminants from the roads can all be washed into the river from no one “point” source. This is known as diffuse pollution.

DiffusePollutionTo illustrate this, there are about 2.5 million cars in London, and 16% of them leak oil. It has been calculated that this would equate to 261,635 gallons of oils dripping onto roads every year! Much of this oil will work its way into London’s surface water drains and then the rivers.

Although changes to the law and car technology may help one day in the future, we need to start acting now. It has been the Wandle Trust’s mission to find out how the contaminated waters from the surface water drains can be cleaned up before entering our river. This is vitally important because water quality is a major determinant of what wildlife can live in the rivers, how beautiful the rivers are, and how much the community value their local water landscapes.

In the current phase of our Pollution Busting Project, four measures are being installed and trialled to determine their effectiveness in reducing the contamination coming into the River Wandle. These measures are the most promising selected from several which were investigated by the Trust and they are called:

  • Downstream Defenders
  • Mycofilters
  • Siltex
  • Smart Sponges

There will be more information about these appearing on our websites in the coming months. We look forward to telling you more about this exciting new phase of our work!