Gröntjärn

The Disappearing Green Lake

Gröntjärn is a small lake about 20 km north from Ljusdal. This part of Sweden is dotted with small lakes so what makes Gröntjärn so special?

As soon as you see your first glimpse of the lake, you'll know it's a lake unlike any other you've ever seen. Gröntjärn means the "Green Lake" and sure enough the colour is very distinctively green, very reminiscent of mountain lakes. The colour is due to lack of particles in the water, and the reason there are so few particles in the water is that lake gets its water from an underground spring without any inlets or outlets of water. Thus the water level in the lake depends on the complex interplay of ground water levels and rainfall so that during times of long droughts the water level sinks, further helped by evaporation. Conversely, during long periods of heavy rainfall the water level rises and ultimately the lake will flood when ground water reservoirs become full. Such a peak in water level took place in the autumn of 2000. Since the lake is situated in a bowl-like geological formation, the flood had no greater impact on the surroundings than causing some picnic tables and firewood to drift away. During the winter the water level sank, and after the dry years of 2002 and 2003 the water level sunk to an extreme low. The documented difference in water levels is 13 metres and although there was very little water at the end of summer 2003, it was still not a new record.

In mid-August I was able to see the bottom of the lake for the first time even at the deepest spot. It is awe-inspiring to walk to the water's edge and look up on the shore and see the bark worn off in the trees some 30m away from you, knowing that it was the ice during the flood winter that had done it...

Gröntjärn is a nature reserve and it is approachable by car, even if the roads get a bit small and bumpy. There is not much information about the lake on the Internet, but the Hudiksvall site offers a picture of the lake during "normal" water level.

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	13 April 2001. This was my first visit to the lake and I was treated to the amazing view of ice chunks hanging from the trees. The lake had frozen over just when the water level was at its highest, and then during the winter the level had gradually sunk.
	27 July 2002. Since the lake is in a bowl and surrounded by forested ridges, it's difficult to get a wide view of the colour. But green it is.
	15 September 2002. As the water level kept receding, I was surprised to find that this little lake had a small island. If you look at the tree trunks on the opposite shore, you'll see a slight change of colouration at about 1.5 metres. That's the flood level. You can also see two paths at different levels, but both of these were under water in 2000. There is an additional path following the ridge on top, and when the water level kept sinking, a new path was formed lower in the bank. The official trail around the lake is 1.5 km, but I suspect that the lower water trail is much shorter!
	10 May 2003. Almost all ice and snow is gone to reveal just a small puddle where a lake used to be. Just look at the sandy shores - the "normal" water level would be just under the tree line. This image is taken from the picnic site, direct path from the parking lot. The ice chunks in the first picture would be above to my right, and the island in the above picture is on the other side of the peninsula in the middle of the image.
	1 June 2003. Just three weeks after the above picture, all the snow and ice are gone now but the sandy shores are still barren. This is the island of the middle picture and it's actually no longer an island because there is a land connection on the right. There is also very little water left in the on the other side, so the small Gröntjärn lake is very close to becoming two even smaller lakes.
	3 August 2003. At first after the spring the water level came up a bit, but has gradually come down again during the summer. There is a little bit of green growth visible on the "island" and on the shores, but mostly the shores are just dried mud, rubble and small rocks.
	September 2003. Autumn is here but despite the occasional rains, the water level keeps receding.
	19 October 2003. Winter is on its way and Gröntjärn has an icy cover and what once was one has now become three.
	6 August 2004. It was a mild and dry winter with little rain falling in this region, even if some parts of Sweden have been flooded this summer. I haven't visited Gröntjärn quite as often as I would have liked recently, so I was a bit surprised to find that the water wasn't at its lowest - it's about the same level now as in June last year. But now I finally managed to capture the greenness of the lake in a picture and name makes perfect sense as you can see!
	27 November 2004. I don't often get to Gröntjärn during the winter, because the roads get unpassable as the snow cover thickens. This was shortly after the first snow and the road wasn't too difficult yet, but it was bitterly cold - coldest day of the winter so far. The autumn rains had done little to the water level.
	27 November 2004. I don't normally photography Gröntjärn from this spot, but exceptions are made - I only had one picture left in the film and it was the last film I was (ever?) going to shoot because the new digital camera was already on order. I was desperate to take the last shot at Gröntjärn because the place has become so special to me. Since I will move westward from Ljusdal, it is unlikely that I will be able to visit the Green Lake any time soon.
	5 May 2006. A year and a half later - finally I'm back! I was expecting to see the water level low and that it was. Seems to be about the same as in 2003.