21 April, 2024

Back in 2019, the kids – so much younger back then! – and I helped undertake some crowdsourced citizen science for the Thames WaterBlitz. This year, we’re helping out again.

Screenshot from FreshWater Watch's slightly-shonky dataviewer, showing that 3 participants took a sample from Oxford Canal bridge 228 on 21 September 2019. — It really is “open data”. Look: I found the record that was created as a result of the kids’ and my participation back in 2019!

We’ve moved house since then, but we’re still within the Thames basin and can provide value by taking part in this weekend’s sampling activity. The data that gets collected on nitrate and phosphate levels in local water sources – among other observations – gets fed into an open dataset for the benefit of scientists and laypeople.

Two young children assess the colour of some canal water, beneath a bridge. — The kids were smaller last time we did this.

It’d have been tempting to be exceptionally lazy and measure the intermittent water course that runs through our garden! It’s an old, partially-culverted drainage ditch¹, but it’s already reached the “dry” part of its year and taking a sample wouldn’t be possible right now.

Two children wearing wellies stand in a ditch, breaking ice into chunks. — The ditch in our garden is empty 75% and full of water 25% of the time. Oh, and full of ice for a few days each winter, to the delight of children who love smashing things. (It’s also full of fallen wood and leaf detritus most of the year and JTA spends a surprising amount of time dredging it so that it drains properly into its next section.)

But more-importantly: the focus of this season’s study is the River Evenlode, and we’re not in its drainage basin! So we packed up a picnic and took an outing to the North Leigh Roman Villa, which I first visited last year when I was supposed to be on the Isle of Man with Ruth.

Dan kneels on a striped picnic mat with a 7-year-old and a 10-year old child alongside some sandwiches, iced fingers, Pepperami, fruit, and pretzels. — “Kids, we’re going outside…” / “Awww! Noooo!” / “…for a picnic and some science!” / “Yayyy!”

Our lunch consumed, we set off for the riverbank, and discovered that the field between us and the river was more than a little waterlogged. One of the two children had been savvy enough to put her wellies on when we suggested, but the other (who claims his wellies have holes in, or don’t fit, or some other moderately-implausible excuse for not wearing them) was in trainers and Ruth and I needed to do a careful balancing act, holding his hands, to get him across some of the tougher and boggier bits.

A 7-year-old boy in a grey camo coat balances on a blank over a large muddy puddle: he's about to attempt to cross a log to a gate into the next field (which also looks pretty wet). Ruth, who doesn't much like featuring in photos, has been digitally-removed from this one (she was standing at the far side ready to catch the balancing child!). — Trainers might not have been the optimal choice of footwear for this particular adventure.

Eventually we reached the river, near where the Cotswold Line crosses it for the fifth time on its way out of Oxford. There, almost-underneath the viaduct, we sent the wellie-wearing eldest child into the river to draw us out a sample of water for testing.

Map showing the border between Gloucestershire and Oxfordshire as defined by the original path of the River Evenlode near Kingham, but the Evenlode has been redirected as part of the construction of the railway, putting two small bits of Gloucestershire on the "wrong side" of the river. — As far as Moreton-in-Marsh, the Cotswold Line out of Oxford essentially follows the River Evenlode. In some places, such as this one near Kingham, the river was redirected to facilitate the construction of the railway. Given that the historic Gloucestershire/Oxfordshire boundary was at this point *defined* by the river, it’s not clear whether this represents the annexation of two territories of Gloucestershire by Oxfordshire. I doubt that anybody cares except map nerds.

Looking into our bucket, we were pleased to discover that it was, relatively-speaking, teeming with life: small insects and a little fish-like thing wriggled around in our water sample². This, along with the moorhen we disturbed³ as we tramped into the reeds, suggested that the river is at least in some level of good-health at this point in its course.

A 10-year old girl wearing sunglasses and purple wellies holds her skirt up out of the water as she wades up the muddy bank of a river carrying a tub of water. — I’m sure our eldest would have volunteered to be the one to traipse through the mud and into the river even if she *hadn’t* been the only one of that was wearing wellies.

We were interested to observe that while the phosphate levels in the river were very high, the nitrate levels are much lower than they were recorded near this spot in a previous year. Previous years’ studies of the Evenlode have mostly taken place later in the year – around July – so we wondered if phosphate-containing agricultural runoff is a bigger problem later in the Spring. Hopefully our data will help researchers answer exactly that kind of question.

Children stand around at a riverside stile while a colour-changing chemical in a vial does its thing. — The chemical experiments take up to 5 minutes each to develop before you can read their colours, so the kids had plenty of time to write-up their visual observations while they waited.

Regardless of the value of the data we collected, it was a delightful excuse for a walk, a picnic, and to learn a little about the health of a local river. On the way back to the car, I showed the kids how to identify wild garlic, which is fully in bloom in the woods nearby, and they spent the rest of the journey back chomping down on wild garlic leaves.

A 7-year-old wearing his coat inside-out and as a cape runs excitedly into a forest path overgrown with wild garlic. — Seriously, that’s a *lot* of wild garlic.

The car now smells of wild garlic. So I guess we get a smelly souvenir from this trip, too⁴!

¹ Our garden ditch, long with a network of similar channels around our village, feeds into Limb Brook. After a meandering journey around the farms to the East this eventually merges with Chill Brook to become Wharf Stream. Wharf Stream passes through a delightful nature reserve before feeding into the Thames near Swinford Toll Bridge.

² Needless to say, we were careful not to include these little animals in our chemical experiments but let them wait in the bucket for a few minutes and then be returned to their homes.

³ We didn’t catch the moorhen in a bucket, though, just to be clear.

⁴ Not counting the smelly souvenir that was our muddy boots after splodging our way through a waterlogged field, twice