Tag Archives: River search

Cranleigh’s rivers – are they healthy?

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Testing of Cranleigh’s rivers has always taken place occasionally and now  Surrey Wildlife Trust is helping to get more testing done and some improvements made.

Chemical levels are measured by groups of volunteers as are the numbers of river fly larvae, which indicate the health levels.

It is a fact that all sewage works clean the water as best they can before letting it go into the rivers. Here are two more facts:

  1. The levels of chemicals that remain, although allowed by government, are not good for wild life and cause the depletion of fish and their natural foods.
  2. In a flood situation, foul untreated sewage does come up in people’s homes which is why all the possessions have to be destroyed in the worst cases.

River dipping is a much needed and scientific past-time that some of us have undertaken on everyone’s behalf . We are hunting for river-flies as they are known, the tiny lavae of various species such as cadis fly, which are collected, counted and returned to the rivers. Afterwards the data collected is viewed by experts.

At a recent dip we found just one lava along with shrimps, and so the water is probably not to their liking, too many chemicals from somewhere.

We were dipping near to the back of Cranleigh Golf and Country club.

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River Search

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One of the great concerns of Cranleigh Civic Society is the ongoing damage caused to Cranleigh Waters by the outflow from the sewage works on the Elmbridge Road. Although the effluent has been treated, Thames Water has a licence to pour the equivalent volume of two Olympic sized swimming pools worth of waste into this tiny stream. This simply cannot be good for anything living there, be it a plant or a fish. We paid a laboratory to test what was going into the stream and they reported that alongside the ‘solids’ that are allowed to go in, they found excessive levels of phosphates. Thames Water confirmed that this is the case but explained that they have no technology to resolve the problem. We find it difficult to accept that they know that they’re causing harm yet have no intention of stopping. As thousands more homes are built in the area this problem will become worse still.

Because we wanted to understand the consequences of this vast volume of effluent entering this delicate waterway, members of our team underwent specialist training from Surrey Wildlife Trust to become accredited river wardens. With this knowledge we undertook the first of our quarterly surveys to lay down a baseline for future surveys to be compared with.

River Search training with Surrey Wildlife Trust
River Search training with Surrey Wildlife Trust

We were trained to look at the vegetation in the water, at the margins and on the banks. Each area offers specific information that describes the health, or otherwise, of the water body. Next, we looked at how the water flowed to give various habitats to suit a variety of creatures and plants, plus many other revealing factors. Little by little a highly detailed map was created from a distance upstream of the sewage works and around the outflow itself.  Despite our polite requests, we were unable to gain permission from landowners to continue our survey downstream.

We’re sad to report that the stream is in very poor condition, made worse by long sections of inappropriate dredging that has stripped the stream bed of any life. This has also slowed the flow damagingly, making any chance of recovery take much longer than desirable.

We also invested in a calibrated water flow meter and have been taking readings to try to understand the stream’s habits. Many of us have seen the flow slow to a trickle and even dry up completely at times. This means that the only liquid flowing towards Bramley has been through our toilets first. It comes as no surprise then that Bramley Fishing Club has given up and closed. When your members no longer catch any fish, there’s no point in carrying on and perhaps this tells us all we need to know.

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