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Why finding a snake in your open water swimming spot is a good thing

Last weekend I decided to take a closer look at the River Mole to see if it’s suitable for swimming. The Mole flows into the Thames opposite Hampton Court, which for me gives the possibility of a wild swimming opportunity within easy cycling distance of my house. I’ve crossed the Mole many times on bike rides but had never swum in it before.
The first challenge was to find a suitable access point. I turned to the Outdoor Swimming Society’s Wild Swimming Map where Peter Ratcliff has posted a short piece about swimming in the Mole near Cobham but that was further than I wanted to go so I settled on West End Recreation Ground in Esher, just next to the bridge where the A244 crosses the river.

There are a couple of easy access points here where the bank slides gently into the water. Rather than diving straight in I went out first on a stand-up paddle board (SUP). The SUP is a great piece of kit to explore potential swimming spots as it keeps you safely away from underwater obstacles and, because you are standing, you can see everything around you.

The current was gentle and I set off upstream. I hadn’t expected to find such a beautiful and wild-looking river so close to London. Initially I passed a few well-appointed (but possibly flood-prone) private houses and I could hear the A244 running close by but soon that all fell behind and I had the illusion of being somewhere truly remote. The banks are untamed and where trees have fallen into the water they have just been left creating natural barriers. The water is a healthy green colour with abundant plant and insect life including hundreds of dragonflies. A couple of bright flashes of blue might have been kingfishers but best of all, and something I have never seen in a UK river, was coming across a young grass or water snake (natrix natrix) purposefully swimming from one side to the other.

As for swimming, this stretch of the Mole is probably better suited to head-up relaxed breast-stroking than head-down effortful freestyle. While it is scenic, the river is full of branches and other (mostly natural) debris. The 1.75 mile stretch I paddled had very few possible exit points so you would probably want to stay close to the recreation ground. The river bed, especially around the entry points, is stony. I was glad to have something to protect my feet.

The Environment Agency rates the water quality as B on a scale of A to F, where A is very good – but the last data on their website is from 2009, and was measured further downstream, below the outflow from Esher Sewage Treatment Works. It should have improved since then. Still, effluent from Reigate STW is discharged into the Mole further upstream and at its upper end the Mole passes through a culvert under Gatwick Airport which has, in the past, resulted in pollution incidents, so it’s right to be wary.

On the other hand, while some people might be put-off by the snake, the fact that I saw one suggests the water quality is good. I saw a good few fish too and, according to Wikipedia, “the Mole now boasts the greatest diversity of fish species of any river in England.” Short of doing any water quality testing myself, this was good enough for me.
The main thing I found off-putting was the amount of dog mess around the river bank, which was especially frustrating as there is a dog-mess bin available. There were also a few piles of rubbish that had been abandoned by picnickers. I’m sure if more people swam in open water they’d be less inclined to leave their dog mess and rubbish next to it.

Incidentally, water snakes are not poisonous and this one was doing its best to get away from me as fast as possible, so its presence is really something to delight in rather than worry about. It was a reminder that open water swimming immerses you in nature, and that’s one of the best things about it.

A quick guide to assessing a potential open water swimming spot

  • Identify your entry and (more importantly) exit point(s). Make sure you are not trespassing in order to reach the water.
  • Assess the water quality. Biodiversity is a good indicator of a healthy, living river. You can also check the Environment Agency’s website and look at a map to see if there are any sewage treatment works discharging nearby. River water quality is usually worse after heavy or prolonged rainfall.
  • Check the depth – and for any sudden changes in depth. I prefer deep water where my hands and feet are not constantly touching water plants.
  • Will you need shoes or wetsuit socks to protect your feet from sharp stones?
  • Toss a stick or a handful of leaves into the stream to check the current. Remember that the current will vary if the river becomes shallow or narrows. Some rivers (including the Mole) are also subject to rapidly increasing currents after rainfall. Be especially cautious if your swimming spot is downstream of a dam from which water may be unexpectedly released.
  • Check for debris, such as fallen logs, in the water. At worst, these can be dangerous if you get pushed against one (or beneath one) by a strong current. They can also cut and scratch you.

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I created Outdoor Swimmer in 2011 (initially as H2Open Magazine) as an outlet for my passion for swimming outdoors. I've been a swimmer and outdoor swimmer for as long as I remember. Swimming has made a huge difference to my life and I want to share its joys and benefits with as many people as possible. I am also the author of Swim Wild & Free: A Practical Guide to Swimming Outdoors 365 a Year and I provide one-to-one support to swimmers through Swim Mentoring.