This water-reservoir has been built between years 1925 and 1934. The pier is 42 metres high, 165 metres high and lies between rocks of the castle Oheb and the castle Vichtejn (often called “Vildstejn). The pent water makes a lake 7 kilometres long and 220ha large, the water capacity is 22, 1 millions of square metres. On its shore the largest recreation area in Chrudimsko has created. During summer as much as 50 000 holidaymaker rotate here. The lake is beside its water service and recreation function a place of fishery as well. The Oheb castle located on a point over the water level was firstly mentioned in 1315 and already in 1553 uninhabited. The name is derived from the Chrudimka river, formerly called Ohebka, from the west direction to the east. The slopes around the ruin are part of natural reservation with a wood and varied herbal scrub and a big appearance of shellfish. A duck-hawk nested here even in 1945. The foot-wall has created the rocks along the river, the slope under the castle ruin as well as “Markova” rock and surrounding rubble fields. The nearby town Sec is the starting point of Vlastivedna trail through the Iron mountains (Zelezne hory) region, which goes from Sec to Ronov nad Doubravou.