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Building a natural clay-lined pond at the windmill

Back in January, digging holes to plant vines taught me a lot about the soil on the property. We planted a few things here and there last year, but this was the first chance I'd had to really spend a good amount of time getting my hands dirty. Of course, the ideal situation would have been to know as much as we could about the soil before actually getting to the point of planting vines. And this wasn't for lack of trying - we even posted a soil sample kit to ourselves from the UK (thinking a box filled with test tubes might not get through airport security!) and had a go. We duly opened sachets of white powder and mixed them with soil and water, waiting to see if they would turn blue or green or whatever, promising information about the nutrients, pH, and all manner of things. I personally didn't see how mixing anything with soil and water would result in any colour but brown, and, unfortunately, I was proved right. So the analysis was shelved and we just ordered a mix of grape varieties that we like to drink, and put the vineyard where we thought made most sense. And so far, so good: 100-odd vines have been in the ground 6 months now, and only one hasn't made it. More about developments in the vineyard in another post soon. 

The main thing I discovered from all that digging is that we have clay on the land - a lot of it. So at the back of my mind since then has been what we can do with this natural resource that we have an abundance of. One project that we've recently started was a clay oven, and one that we've just finished is a clay-lined pond. 

We have a piece of land just down from the mill on the north side, with great views out into the mountains, and which could provide a little private space for guests to relax. There was already a table there when we arrived, made out of an old millstone, and it's a lovely place to have a coffee and watch the sun come up. It was, however, a bit of a mess. Perhaps 'wild' is a better term. We had plans to do something with it early in the year, but hadn't got round to these by the time we started receiving guests back in March. Deciding we didn't want it looking like a building site with guests here, we put our plans off until after the season. Then, of course, Covid hit and we had no guests. Back to the building site!

A happy frog in our new pond! Thanks to our recent guest Marta for the great photo.

The first thing I wanted to try was a pond, as - having never had a go at anything like this before - I knew there was a high possibility we'd end up with little more than a big muddy puddle and I wanted plenty of time to fill it in again if needed! The other reason a pond made sense for us specifically - aside from all the benefits to the land and the wildlife - was that we have constantly running water from the river here, essentially siphoned direct from a waterfall upstream. When we're not using it to fill the tank that provides us and the guests with water for washing (drinking water comes from a controlled natural spring up in the mountains), which is most of the time, that water is just running off onto the land to no real purpose. So the idea is to eventually have a system of ponds and tanks around the mill and down the slopes, retaining as much of the water as we can on the land. 

I'd already been collecting the clay for a while before we started. I'm sure you can get perfectly good, and perhaps even sustainable and environmentally-friendly, pond liners, but I was drawn by the idea of using the clay we had on the land, and learning how to use it. So, over a period of a few weeks - usually after some rain when the ground was nice and soft - every now and then I would dig up a bucket of clay and start working with it. For this I took advice from this article, and began rolling my sleeves up and mixing the clay with water, sieving it into a bucket to remove stones and other materials, and leaving it to evaporate back into solid and much more pure clay. Given that the article is more about producing clay of a quality for pottery, this was probably slight overkill, but I was in no hurry and we had plenty of sunshine to get the job done quickly. Not to mention that I quite enjoyed making what was basically a massive mud pie...

When it was time to start the pond, we picked an area and started digging - not deep, maybe half a metre. When we had a shape we liked I took some of the clay and packed it around the edges and bottom, stamping on it and punching it to get all the air out and leave it watertight. Watertight enough, anyway - this site suggested 8 inches of clay in total and ours is probably not even 1 inch, but because the water is running constantly, this is sufficient. We placed some stones on top of the clay - initially trying to pick pretty ones from the little beach area down by the river, but this turned out to be a little pointless, as anything on the bottom of the pond has gradually been covered with a layer of deposit since then. We also created a small channel for the water to flow out of and down the hill towards future additional ponds; and planted a couple of trees along the course, very happy in the knowledge we don't need to worry about adding them to our already gruelling watering regime during the summer (we've already hit 40 degrees centigrade a few times this year). 

Skittle may have spotted a frog...

We then extended our water tube round to an area above the pond, and let the water run down to see what happened. And it filled up! For the first few days, it didn't look entirely dissimilar to that muddy puddle mentioned above, and I was definitely concerned about having to fill everything in again, but after a few days and the addition of some aquatic plants, we came down one morning and it was crystal clear!

There were just two things left to add - the first was some frogs, kindly caught and donated by our friend Gady and his children. The other was a water feature - the Fadagosa Cascadas (see video below)! We initially had the water trickling down a sort of 'wall' above the pond, but we were worried about that eroding over time. We'd visited a friend and been impressed with how they had used traditional Portuguese roof tiles around their pond, so - with some help from Gady - we copied the idea and finished it off with a hollow piece of cork we had been given as a gift by some guests earlier in the year. Thank you João and Mafalda! 

A few weeks later we still have a lovely clear pond, at least three frogs, some rapidly growing aquatic plants loving all the sunshine; and we've also added a hammock, so you can while away the warm evenings being rocked by the breeze and listening to the water running beside you... and now we're open again you're very welcome to join us and do just that! 


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