Lake Kerkini is a wetland located north of the city of Serres.
More than 300 species of birds have been listed in the lake and the surrounding mountains. Two of them, the silver pelican and the pygmy cormorant, are globally endangered. The most important colonies of the southern Balkan peninsula of cormorants, grebes, and coots can be observed alongside various species of herons, while in recent years new species have been observed for the area such as the dwarf goose, the palm hawk, the harrier, the golden eagle, the peregrine falcon, the spotted eagle and others. However, some species, such as the sea eagle and the golden eagle, the savi’s warbler and the western marsh harrier no longer nest here, due to the changes in their nesting sites.
Nowadays, the diversity of vegetation, the presence of hundreds of species of birds, the rich fish fauna and the many species of mammals, reptiles and amphibians that exist in the area are the natural continuation of the life that existed before the construction of the dam.
The construction of the artificial lake tamed the waters of Strymonas river, contributed to the fight against the nightmare of malaria, gave life to the fields and helped the economic development of the prefecture and the rehabilitation of the 85,000 refugees from the Asia Minor disaster. In 1982, the constant reduction of the lake’s capacity, due to the materials carried by the Strymonas river, led to the construction of a new dam that raised the lake’s level.
Lake Kerkini has rich vegetation with plants that float on the surface of the water, plants rooted in the bottom that grow under or on the surface (water lilies) and plants of reed beds and wet meadows. The nutrients that Strymonas river brings into the lake favored the growth of vegetation.
Extensive reed beds with wetland species, such as rushes, are almost disappearing. Hydrological conditions favored the development of a colorful carpet of water lilies at the northern ends of the lake. Unfortunately, the large fluctuation of the water level each year threatens to wipe them out and turn the lake into a mere water reservoir.
In the north-eastern part of the lake, at the mouth of the Strymonas river, there is the riverside forest which is the main feeding and nesting place for many rare birds, as well as a breeding and growing place for fish. Until a few years ago, many types of trees that gave a special color to the landscape were encountered. Due to continuous erosion, today mostly willows remain. The area of the forest has been reduced from 7000 hectares in 1980 to almost half, and if it continues to flood at this rate, it is in danger of disappearing completely.
The surrounding mountains of Kerkini (surrounded by mount Beles) and Mavrovouni (surrouded by mount Krousia) are covered with forest vegetation, mainly beech in the higher parts and many species of oak mixed with linden, hazel, anchovies and other deciduous and evergreen shrub species in the lower areas. Also, there are many wild flowers decorating the mountain slopes with their colors.
In the wider area of Lake Kerkini, there are mammal species, several of which are endangered, such as the otter, the deer, the jackal, the wolf and the wild cat, while there are also several common species such as the fox, the weasel, the wild boar, the hare, the hedgehog and the badger. Also, in the forest, as well as in the surrounding areas, 10 species of amphibians and more than 20 species of reptiles can be found.
The fish fauna of the lake is great too. In the most part of Kerkini Lake – Strymonas River system, more than 30 species of fish of commercial interest have been listed, such as carp (grivadi) and butterflyfish, and it represents a highly productive fishing area. After the construction of the new dam in 1982, the Eel and the catfish (Goulianos) disappeared from the lake, while the number of Carps was greatly reduced.
Lake Kerkini is a precious ecosystem with a multitude of values. The best of them are:
1) Anti-flooding: It plays a key anti-flooding role by holding back the waters of Strymonas river and preventing the risk of flooding in the lower part of the flatland of Serres.
2) Irrigation: Provides water for irrigation in a large part of the prefecture of Serres, which has a strong agricultural character and is one of the most productive in the country.
3) Fishing: Lake Kerkini is one of the richest lakes in Greece and many of the residents of the lakeside communities are engaged in fishing.
4) Biodiversity: The existence of the lake and wetland vegetation provides food and shelter to many species of wildlife. For this reason it was included in the list of Wetlands of International Importance and is protected by international treaties.
5) Educational: It is offered for environmental education training both for the students of the prefecture of Serres, and for students from the rest of Greece or from all over the world.
6) Recreational: The visitor can rest and the lake can be the development center of mild ecological tourism activities, thus contributing to the strengthening of the residents’ income.
7) Scientific: It is an important area for scientific research on wetlands, their management and the anthropogenic effects on their functions, due to the diversity of its biological wealth and the activities that develop in the area.
The main problems of the wetland are related to the uses of the water. The protection of Lake Kerkini directly depends on the judicious use of water, in order to ensure to the maximum extent possible all the functions and values of the wetland. The one-sided view of Kerkini as a simple water container, existing only to satisfy irrigation needs, is surely outdated. The same applies to the view of the “absolute protection” of the lake, which does not take into account the social and economic needs of the inhabitants. Depending on the supply of the river and the opening and closing of the sluice gates, there is a strong fluctuation of the water level that reaches 5.5 meters. Corresponding is the fluctuation of the area of the lake, which ranges from approximately 55,000 to 75,000 acres. The lake level reaches its maximum height in May in order to save sufficient amounts of water for irrigating the fields during the summer.
The entrained materials that continue to flow into the lake are constantly reducing its capacity. Also, the mediocre condition of the irrigation networks causes large water losses. So if we want to continue satisfying the same irrigation needs, we are led to a continuous annual rise in the water level. But the rise of the water level has a negative effect on the ecosystems of the lake because it reduces or eliminates the shallow areas and mudflats that are essential places for feeding, reproduction and nesting of many birds, amphibians and fish.
Also, the high water level naturally causes serious problems for the lakeside settlements that are lower than the lake surface, increasing the risk of flooding from overflow and from raising the underground water level.
The problem is compounded by the fact that water cannot validly escape by opening the dam gates, as the dimensions of the Strymonas river bed below Kerkini lake can only accept small amounts of water. Larger amounts of water will cause flooding in areas lower than the dam. The effort to ensure that the amount of water leaving the lake is as much as the existing bed can drain, has the consequence that for some periods of time, more water remains in the lake than is required for irrigation. As a result, the lake level rises, sometimes above the maximum irrigation level.
Efforts to conserve water by retaining alluvium, reconstructing and improving irrigation networks, recycling water and implementing new irrigation techniques (such as better leveling of fields) will improve irrigation efficiency, without the need for a higher water level. Along with the correct instructions from the competent services, farmers must be informed and encouraged about the correct use of irrigation water.
Through coordinated management efforts and with the cooperation of the competent services and organizations, it is possible to satisfy all water needs, with the lake continuing to fulfill its multiple role. Future actions must also take into consideration the economic value of Lake Kerkini. Raising the dikes can likely be disastrous for the lake, as it does not ensure that the waters will not rise to the height of the new dikes. A possible rise of the water level will result in the destruction of the rare riverside forest, which is the most important breeding and feeding place for wild animals, while it will contribute to the substantial degradation of all the features that make Kerkini lake stand out today as an area of global interest and special natural beauty.