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Water Quality Catchment Management Plan, Lake Ülemiste, Estonia

Drinking water for the capital city of Tallinn, Estonia (pop. 0.5 M) is supplied from nearby Lake Ülemiste, which is recharged by a major regional system of linked rivers and canals from a 1700 km² catchment.

The lake is eutrophic in summer, with occurrences of Cyano-bacteria. The quality of the water delivered into the reservoir is a function of the natural characteristics of various sub-catchments, (with sources of point and diffuse pollution from agriculture and urban areas).

This makes for a complex variation of water quality, showing strong seasonal and geographical patterns, with consequent problems in managing efficiently the water treatment process, especially the costs associated with the major ozonation plant recently installed.

As the Water Resources specialist, Brian Faulkner undertook detailed investigations into the sources and variation of nutrients reaching the lake, especially nitrates and phosphates.

A MapInfo™ GIS was implemented, and combined with the client's Access™ chemistry database holding many years of sampling records from 20 key sites throughout the region.  SPOT satellite imagery was locally obtained and used in the GIS to provide new insights into geographic sources of pollution.

Analysis of data, water quality modelling and a review of current operating practices showed that more active control of the canal system at key runoff periods - spring and autumn - might improve water quality in the lake and yield a noticeable reduction in operating costs with relatively little capital investment.

A catchment management plan was prepared, which emphasised the cost advantages of dealing with water quality problems at source rather than at the treatment works which can be energy intensive and costly.

Client - Tallinn Water Ltd. / Parkman International
Date - May to July 1997, April to May 1998
Funding - ODA / Foreign Office 'Know How' Fund
Scheme value - £1.5M
Support tools - SPOT™, Excel™, Access™, MapInfo™, Lowrance GPS