Lake Garancsi

Garancsi Lake is located between Piliscsaba and Tinnye, in the latter's outskirts, in a beautiful setting.

It is the only lake in the region that has existed for centuries and is a popular excursion spot. The lake and its surroundings are a locally protected nature reserve. It is a favourite outing place for residents of the capital and was formerly a fishing lake as well.

The "scenic" lake was formed in a valley enclosed by gentle hills; it was long considered to be of natural origin, but recent research indicates that it was created by anthropogenic influence sometime in the Middle Ages, displaced by road construction, in a clayey valley. Several legends and folk tales have developed in the surrounding settlements about the lake and its area.

Location

Garancsi Lake formed at the meeting point of the Zsámbék-Bajnai hill region, which makes up the eastern part of the Buda Mountains and Gerecse, along a northwest‑southeast fault line, at an altitude of 240 metres above sea level. It is surrounded on three sides by rolling hills, while to the northwest it is bounded by the country road between Tinnye and Piliscsaba, beyond which a narrow, intermittently water‑flowing valley lies. At average water level its deepest point is 240‑260 cm, and the total area of its catchment is approximately 60 hectares.

Hydrography, water quality

The lake's first known cartographic depiction appears on a military map from the reign of Emperor Joseph II; at that time the lake's area was about 39 000 square metres, and unlike its present state it still had an outflow, with a surface watercourse leading toward Meleg Valley. Later, however, due to lack of water replenishment, its area decreased and it became endorheic.

The chemical nature of the water is weakly alkaline, magnesium‑hydrogen carbonate‑sulfate type; according to 2001 measurements the water contains 152 mg of magnesium per litre, 387 mg of bicarbonate, and 501 mg of sulfate.

Based on pollen and heavy metal water analyses, it appears that the area has undergone several major changes over the past centuries: initially, despite the large extent of water coverage, it was an extremely shallow, swamp-like lake with strongly alkaline water; over time the depth increased for a while, then probably began to shallow again due to reduced precipitation, while its salt content increased. From the mid‑1980s onward, massive proliferation of species favoring extreme nutrient enrichment became characteristic.

From the beginning to 1970

According to the latest research, the lake was not formed naturally but by back‑flooding of groundwater, already in the Middle Ages, after the construction of a transport route, and its water supply is not provided by springs as previously assumed; its water volume depends solely on precipitation.

There are records of the lake’s fishery use already from the Turkish period; in a 1546 inventory its fishery value was estimated at 100 forints; the utilization of the reed growing here (its harvesting and its use for covering serf houses) is also known from data dating back to the 18th century. In addition, the water was used for hemp soaking and for cutting ice in winter; the ice extracted here was sold by the locals to nearby inns and butchers.

When it became a tin‑owner’s estate in 1842, it also attracted the attention of Lajos Kossuth, who wanted to make the beautifully situated lake suitable for bathing, and therefore asked Pál Vásárhelyi to explore the lake’s sources. Unfortunately this did not happen, most likely because the renowned water‑improving engineer died unexpectedly in the spring of 1846.

In later decades the clay found in the valley was tried to be utilized more: primarily the clay extracted here was used for building the peasant houses of Tinnye, but at one time a brick factory also operated near the lake. In the 1950s a duck farm operated on the lakeshore for a while, and in the surrounding areas corn and grain were also cultivated, all of which apparently contributed significantly to the nutrient load of the lake water.

Since 1970

Between 1970 and 1973 the Hungarian News Agency rented from the Töki Egyetértés Agricultural Producer Cooperative. The lake was then very algae‑laden, therefore several pike perch (a plant‑eating fish) were introduced here. The cooperative’s workers, together with anglers from Töki, Perbál, Tinnye and Piliscsaba, founded the Töki Egyetértés Fishing Association in 1973, whose name was changed after the regime change to Garancs‑tó Fishing Association; the association’s membership fluctuated between 160 and 250 persons.

The water surface originally was 4 hectares, but already in the mid‑1980s it began to silt, and the thickness of the mud also increased considerably. The cooperative and the then Piliscsaba council commissioned a plan in 1987 for dredging the lake basin. According to the plans completed by the end of 1988, the dredging together with shoreline arrangement would have cost about seven million forints, but since after the regime change the Töki Producer Cooperative was dissolved and the ownership of the lake passed from Piliscsaba to the municipality of Tinnye, the dredging did not take place.

Since the 1990s the lake’s water surface began to shrink rapidly, and in parallel – due to the decline in fishing opportunities – the association’s membership also started to decline sharply. The association’s leaders and members continuously tried to care for and manage the lake: in addition to regular fish stocking, they conducted water tests every year and maintained the shore, but because they could not reach an agreement with the lake’s new owner, the municipality of Tinnye, and could not conclude an acceptable lease or usage contract, they were also unable to apply for further development. The fishing association, among other things, tried to seek assistance from the Hungarian National Fishing Federation, the Ministry of Agriculture, and the environmental and water authorities, but unfortunately could not obtain financial support from any source, so despite several newspaper articles and television publicity on the subject, the rehabilitation of the lake and its environment was not achieved.