Dam openings unnecessary

Photo: Margus Muld

The dam connecting the islands of Saaremaa and Muhumaa, known as Väinatamm, has had a positive effect on water quality in the strait, marine scientists find after discussing the matter following a request from the environment minister.

«The meeting led to a somewhat amusing situation,» said President of the Estonian Academy of Sciences Tarmo Soomere after the September 9 meeting. «Never in the past 25 years have I seen scientists from four institutions agree on every single talking point,» Soomere said.

Minister of the Environment Marko Pomerants called the meeting to establish whether cutting openings into the dam running across Väike Väin would help improve the ecological situation of the strait. Researchers were unanimous: openings are not necessary as they would produce no obvious improvement.

On the contrary, samples taken from the strait over the years suggest the situation has actually improved. There is no sense in disturbing a natural environment that is slowly improving, scientists agreed.

Yes, the sea level has dropped and reeds are gaining ground; however, these changes would have taken place without the dam, as the ground is rising everywhere in Northern Estonia and the western islands, whereas the strait growing over is an inevitable process in the long run. Cutting two tunnels, both spanning several dozen meters, in the dam would have no effect except the project's estimated 10 million euro price tag.

Plans from the 1980s

Because throughflow is minimal in the predominantly one-meter deep strait, openings would only have an effect within 100 meters of the dam. «Perhaps they could be used to let a boat pass under the dam every now and then; however, they would produce no changes in the marine environment,» said leading research fellow at the University of Tartu Estonian Maritime Institute Georg Martin.

Environmental activists blame dwindling fish populations in the strait on the dam. The conclusion of scientists is more down to earth: coastal fish populations are in decline everywhere in the Baltic Sea, making the strait no exception.

Martin has been dealing with the dam for the past 23 years. Plans to cut openings for the water in the dam were drawn up in the late 1980s. While work got as far as building temporary bypasses for vehicles crossing the dam, funds ran out before work on the tunnels could begin.

The 18-meters wide openings were not built, while the idea lingered. Local activist Heiki Hanso organized an event to draw attention to the strait growing over and the fish disappearing this summer.

While Minister Marko Pomerants did not take the trouble to discuss the matter with Hanso at length at the time, he eventually asked the opinion of scientists. «Surveys carried out in 1995 showed that openings for the water would not improve the situation in the strait to any notable degree,» said Martin.

Regular tests show satisfactory quality of water in the strait, which cannot be said for Pärnu, Tallinn, or Haapsalu straits.

Martin said that eight different indicators are measured in seawater, and the only one that comes up less than «good» in Väike Väin is algae proliferation.

«That is to say the Väinatamm poses no threat to marine environment,» Academy of Sciences President Soomere said. «Everything happening in that strait reflects general changes in the Baltic Sea. There is no problem these openings could fix.»

Human factor not a problem

Soomere said that the dam was built in the late 19th century in the lowest part of the strait where water moves very little. «Water mobility in the Väike Väin is just 1 percent of what it is in the Suur Väin. The problem is that the very shallow strait is also narrow – between two and four kilometers – but quite long at 20 kilometers.»

The water level in the strait has fallen by 25 centimeters since its opening in 1896; however, as a result of the ground rising in the northern and central part of the Baltic Sea as opposed to human activity.

Georg Martin said that the effect of human activity is next to nonexistent in the strait as there are no major industries in the area and the water purification equipment of the nearby town of Orissaare has been modernized. «So the human factor as a problem virtually doesn't exist there,» he said.

Martin added that cutting tunnels into the dam would produce no benefit and could cause harm instead. «Changing the water circulation of the strait to a considerable degree could affect the unique floating agar community in the Gulf of Kassari (also known as Hiiu strait, located between the southeastern coast of Hiiumaa, the northern coast of Saaremaa, and the northwestern coast of Muhumaa) which is being used commercially, leading to real economic damage.»