Every big reservoir has a ghost town story. The valley floods, a village goes under, and a couple of generations later a dry year drops the lake far enough that the foundations show up on the local news.<\/p>\n
Lake Mead has done it with St. Thomas, Nevada, more than once. If you’ve driven past any lake in the West lately, you’ve seen the bathtub ring and probably wondered what’s under it.<\/p>\n
Germany’s got one of those going right now. The twist I didn’t expect is that the water company isn’t selling tickets. It’s telling people the ground around the ruins will swallow them.<\/p>\n
The lake’s the Oker reservoir, up in the Harz mountains in central Germany, held back by a curved concrete wall called the Okertalsperre. According to NDR, the public broadcaster for that part of the country, the operator told them on October 23 that the lake is down to 16 percent of capacity, a new all-time low.<\/p>\n
The state’s own gauge had it at 16.22 percent, just over 2 billion gallons, at 8 in the morning on October 24. Full, this thing holds about 12.4 billion.<\/p>\n
And the walls of the village it drowned in the 1950s are standing in the open again.<\/p>\n
Emptier than it sounds, and I’ll explain why, because the percentage is a little misleading if you picture a swimming pool.<\/p>\n
A mountain reservoir is a flooded valley, so it’s shaped like a V with a wide top and a narrow bottom. The top few feet of water cover the most ground and hold the most volume.<\/p>\n
Drain 84 percent of it, which is where the Oker is now, and the shoreline doesn’t drop a little. It walks a long way down the hillside, and whatever used to sit on the valley floor comes out into the air.<\/p>\n
So who decides what counts as a record? The company that runs the dam, Harzwasserwerke, keeps its own books on this, and in July its spokesman Norman Droste told NDR, via the local station Okerwelle, that the previous all-time low was 17 percent in the fall of 2022.<\/p>\n
At that point, in late July, the lake stood at 32 percent, which was already a record for the month. So it lost half of what it had left between late July and now.<\/p>\n
What got it there isn’t complicated. Harzwasserwerke’s October 22 release lays it out: spring 2025 was historically dry, the winter of 2025 into 2026 didn’t bring much either, and the last three months have been unusually dry on top of that.<\/p>\n
At the company’s own weather station at Schulenberg, right on the lake, about 52 liters of rain per square meter had fallen in October as of that release. In American terms that’s roughly 2 inches, and the company says it’s about half of what the whole month normally gets. A couple of recent showers, it says, barely moved the needle.<\/p>\n
The ruins belong to Alt-Schulenberg, a mining village that goes back to the 1500s, when the hills around it were being worked for silver, copper and lead. The last mine closed in 1904, and after that the town mostly cut timber. Then in the early 1950s the regional water authority decided the Oker, which had a habit of flooding Braunschweig and Wolfenb\u00fcttel downstream after the snow melted, needed a dam, and the village was in the way.<\/p>\n
Roughly 300 people lived there. According to the regional paper Leinetal24, they left in August 1954, in a procession to the new Schulenberg built on a shelf about 200 feet above where the water would come.<\/p>\n
The old buildings were knocked down to their foundations, and the valley filled for the first time in 1956. Harzwasserwerke’s own page on the dam gives the construction window as 1952 to 1956.<\/p>\n
Those foundations are what’s showing now. NDR’s photo gallery from October 23 shows low stone walls sitting in gray mud where the lake used to be, and the broadcaster says visitors have taken to calling the spot a “lost place.” The water company’s release is drier about it, in both senses. It confirms the remains of the former village are visible again, and then it spends the next paragraph telling you not to go near them.<\/p>\n
Is it the first time Alt-Schulenberg has surfaced? No. A local paper, the Goslarsche Zeitung, reported the same walls poking out in 2018, when the lake fell to 20 percent and the company called it the lowest level since 1981.<\/p>\n
So the ruins come and go. The difference this time is that there’s less water on top of them than there has ever been in Harzwasserwerke’s accounting.<\/p>\n
This is the part that turns a nice photo into a public safety notice. The release says the dry areas of the reservoir “must not be entered under any circumstances,” and it explains why: the surface looks dry and firm, and it isn’t. The ground underneath can give way, and the company’s words for what happens next translate as a danger of sinking deep into it.<\/p>\n
If you’ve never stood on a freshly exposed lakebed, that probably sounds like overcaution. It isn’t, frankly. What you’re looking at is 70 years of silt that drifted down through still water and settled in layers that have never been compacted by anything heavier than a fish.<\/p>\n
The sun bakes a crust on top a few inches thick, and under that crust the stuff has the consistency of pudding. Put a boot on it and the crust holds right up until it doesn’t, and then you’re in to the thigh, or further, with nothing solid to push against.<\/p>\n
I’ll admit the company’s release doesn’t say whether anyone has actually gone in. It just says the ground will take you if you try.<\/p>\n
So what does a dam operator do when the lake behind it is at 16 percent? Mostly it stops letting water out.<\/p>\n
The Oker reservoir has a few jobs. The first is flood control, which is the reason the village is at the bottom of it. The second is the opposite problem: in a dry summer it releases water so the Oker River downstream doesn’t shrink to a trickle.<\/p>\n
The third is a bit of hydropower. And since 1971, a fourth: water from the Oker can go through a 4.7-mile tunnel to the neighboring Grane reservoir, where Harzwasserwerke runs its biggest treatment plant.<\/p>\n
The Oker itself doesn’t have a treatment plant. It’s a storage tank with a river attached.<\/p>\n
That second job’s the one getting dialed back. Harzwasserwerke says the state water agency, the NLWKN, has approved a special operating plan for the dam that allows it to reduce the downstream release to 1.0 cubic meter a second if needed, which works out to a little over 35 cubic feet a second, to stabilize the level in the lake.<\/p>\n
Has the company actually turned the valve down to that? The release doesn’t say. The NLWKN gauge below the dam was reading right around 1.0 on October 12, which is what you’d expect if the reduction were already running, but the agency itself notes that gauge doesn’t necessarily match the dam’s own release, so I’ll stick with “allowed.”<\/p>\n
For a sense of how far this has swung, the same dam was full and running water over its spillway at the end of December 2023, when dpa reported the release going from 16 to 30 cubic meters a second to make room, about 565 to 1,060 cubic feet. Less than three years later it has permission to send 35.<\/p>\n
We’ve been watching a lot of dams do a version of this lately. A Green River dam in Utah is letting up to a million acre-feet go<\/a> to keep Lake Powell’s turbines turning, and an Arizona dam is standing in a lake pulled down 54 feet on purpose<\/a> so its gates can be serviced.<\/p>\n The Oker is the opposite case. Nobody drained it. It just didn’t rain.<\/p>\n You may be wondering if a dam at 16 percent is a dam in trouble. It isn’t, and here’s why in two sentences.<\/p>\n The Okertalsperre is an arch-gravity dam, which means the concrete wall is curved so it leans part of the water’s push into the rock on either side of the valley, and it’s also fat enough at the base to hold the rest with its own weight. Harzwasserwerke lists it at 246 feet from the foundation and 220 feet above the valley floor, 853 feet along the top, 26 feet wide at the crest, with about 183,000 cubic yards of concrete in it.<\/p>\n A wall like that is designed for the day the lake is full and pushing on it with everything it has. A lake at 16 percent is the easiest day of its life.<\/p>\n The problem’s upstream of the wall. Harzwasserwerke’s drinking-water reservoirs as a group were 45 percent full on October 22 against a long-term average of 67 percent for that date, and the company supplies about 2 million people in Lower Saxony and Bremen from them.<\/p>\n NDR says the S\u00f6se reservoir, another one in the company’s system, is largely dry too. The company insists the taps are safe, and I think it’s right, for a plain reason: it runs a grid, not a single lake.<\/p>\n Water moves between reservoirs through tunnels, and the groundwater wells have been pumping harder to take the load off the mountains. Hendrik R\u00f6sch, the company’s technical managing director, put it in the release as proof that spreading your supply across a lot of sources is what gets you through a long dry stretch.<\/p>\n What would fix it is a wet winter, ideally a snowy one, because snowmelt is what fills these lakes in the spring. The company said as much on October 22 and added that if the dry spell drags on, it has further measures ready to protect drinking water.<\/p>\n It hasn’t said what they are. As of 8 a.m. on October 24, the NLWKN gauge at the Okertalsperre read 16.22 percent, and the walls of Alt-Schulenberg were still out of the water.<\/p>\n","protected":false},"excerpt":{"rendered":" Every big reservoir has a ghost town story. The valley floods, a village goes under, and a couple of generations … <\/p>\nThe wall itself is fine. It’s the lake that’s gone<\/h2>\n