Environmental Monitoring: Lithuania Has Rich Resources of Quality Groundwater2014-04-03
Environmental monitoring conducted by the Lithuanian Geological Survey is a key tool that allows assessing changes in the condition of the waters. A recent research shows that the groundwater resources are abundant, and only a small part of them is being used. The quality is good.
Lithuania Has 20 Freshwater Basins
Lithuanian climatic and geological-hydrogeological conditions are favourable for the formation of fresh groundwater resources. Fresh groundwater accumulates in multi-sedimentary heavy layers consisting of various composition and filtration permeability layers. There are 20 separate groundwater basins that are used for managing groundwater resources in Lithuania.
The quantitative and chemical condition of most of the groundwater basins' (15) is good; they are subject to surveillance monitoring. Five groundwater basins have been identified as being at risk, they have water bodies where chloride and sulphate concentrations in the groundwater are in excess of the drinking water standard due to natural causes. Monitoring of the problematic quality indicators was launched in these basins in 2013.
In 2010-2012, ~ 380,000 cu. m of fresh water per day was extracted in Lithuania from the 1,794 registered water bodies. The amount of groundwater that can be extracted from aquifers without draining the resources and harming the surface ecosystems is called the available resources.
The Biggest Reserves of Groundwater Are Located in the Eastern Part of the Country
The groundwater resources in Lithuania are unevenly distributed: the biggest reserves of groundwater are in the eastern and southeastern parts of the country, as well as along the Neris and Nemunas valleys. The smallest reserves are in Central Lithuania. If we compare the amount of water extracted and the available resources, we can see that only a small part of the resources is currently being extracted in the majority of the groundwater basin. If the groundwater exploitation is reduced and there are quite substantial water resources, negative effects of groundwater exploitation do not occur on a regional scale.
Buffer Strips To Ensure Water Quality
In 2013, nitrogen concentration in the regions did not exceed drinking water standards. Only in local areas -- mostly in urban areas -- the nitrate concentration is approaching the maximum permissible concentration, which is 50 mg / l, and the ammonium concentration is reaching ~ 2.4 mg / l, which exceeds the maximum permissible concentration several times.
To protect water body resources, buffer strips are established where economic activities are restricted. In the Lithuanian Geological Survey's Register of Underground Resources 1,776 operating water bodies of fresh drinking water were registered in 2013, out of which the sanitary protection zone has been evaluated hidrogeologically in accordance with the applicable procedures for 885 water bodies. In the remaining water bodies only a strict regime zone protection still applies.
Water Quality Is Often Determined by Natural Conditions
The chemical status of groundwater basins that are used for drinking water supply, as measured by the state and water body monitoring results in 2010-2013, is good. In many cases, the quality of water that does not meet the drinking water requirements is determined by natural conditions. The available monitoring data from major water bodies, when they are operated at maximum flow, indicates that groundwater exploitation is likely to have an impact on the increase of sulphate and chloride concentrations. The fluoride and ammonium ions concentration does not depend directly on exploitation.
The most difficult situation is in the Joniškis groundwater basin. Sulphate concentrations are higher than 250 mg / l in 84 percent of the water body; moreover, a trend of sulphates increase is being observed. There is no sufficient data to link the increase of sulphate concentration to groundwater exploitation.
In the Stipiniai groundwater basins of the upper Devonian layer, sulphate concentration remains stable.
In the Suvalkija basin chalk aquifers are being exploited. The fresh groundwater in the focus anomalies, which cover 76 percent of water bodies there, is deteriorating because of the chloride ion concentration. Currently, we can observe a trend of chloride concentrations decrease in the groundwater basin.
Public Information Division