The State Forest Management Center (RMK) has been working to make the Varangu dam on the Selja River in Lääne-Viru County, more fish-friendly. The dam, which is on the migration route of salmon and other fish, had previously proved challenging for weaker swimmers to negotiate. The new reconstruction work aims to rectify that, ensuring that all fish can pass through, irrespective of their swimming ability.
For many years, the Varangu dam on the Selja River in Haljala Municipality, Lääne-Viru County, provided a major obstacle for migratory fish. While the weir and bridge structures had decayed over the years, the concrete floor of the bridge pillars continued to cause problems, particularly for those species of fish, which are not such strong swimmers. In particular, issues arose each year during periods of low tide, when water levels above the concrete floor were minimal (often around 5 cm). This also meant that fish attempting to move upstream were unable to do so unless they could first jump over a 70cm-high step.
"Now, Wildlife Estonia (Eesti Loodushoiu Keskus) has installed special equipment on the rapids downstream from the former dam. The aim is to find out, this year and over the coming years, whether the European river lamprey (lampetra fluviatilis), which was previously unable to get over the dam, will (now) manage to migrate further up the Selja River. We have already seen that salmon and trout can successfully cross the barrier and use it as a spawning ground," said Sander Sandberg, aquatic wildlife specialist in RMK's Nature Conservation Department.
"The Varangu water mill dam has a weir downstream, and because the landowner wanted to retain the bridge pillars and restore the bridge itself for crossing the river, the concrete floor, which caused problems in periods when water levels were low, had to be retained during the works. While restoring the bridge pillars, a solution was found whereby the bridge deck would remain passable for fish during periods when water levels are low. It involves diverting most of the water between the bridge's central pillars," explained Sandberg.
"In order to enable the salmon to spawn upstream, a natural-looking artificial rapids has been created, with a low-flow channel in the middle, so that the fish have a place to swim when water levels are low," said Henri Gostsõllo, construction manager at Nordpont, the company responsible for the renovations.
"The rocks are positioned in such a way, that if the fish want to rest when moving uphill from here, they can go behind the rocks to do that and make plans," said Gostsõllo.
The reconstruction work, which was funded by the European Union's Cohesion Fund, cost in excess of €360,000.
Editor: Michael Cole