2. Lake Ülemiste
Largest of the lakes surrounding Tallinn
Main part of the Tallinn water supply system
The Tallinn Water Company, AS Tallinna Vesi, has a treatment
plant on the North shore of the lake which supplies 90% of the
water to the city
Other 10% from ground water wells
On 18 March 2010 a DHL Antonov An-26 aircraft made an
emergency landing on the ice of Lake Ülemiste and 1,5 tons of
fuel leaked into the water
3. Lake Ülemiste
Max. length 4.1 km
Max. width 3.2 km
Surface area 9.436 km2
Average depth 2.5 m
Max. depth 4.2 m
Shore length 15.219 km
Surface elevation 35.7 m
4.
5.
6. Macroflora of lake Ülemiste in 2000
Macrophyte vegetation covered 5.4% of the lake, 6% in 2004
The mean width of the zone of macrophytes was 48.4 m and
the mean depth 1.4 m.
Widest belt was in south-west part of the lake – 286 m
The list of the macrophytes found over the entire lake contains
41 species of vascular plants, 1 moss species, and 5 species of
macroalgae.
10. Species Number of findings Frequency, % Depth limits, m
Common reed /
pilliroog
133 57.3 0.2-2.5
Common club-rush /
järvkaisel
97 41.8 0.2-1.9
Water knotweed /
vesi-kirburohi
62 26.7 0.3-2.0
Common rivergrass /
rooghein
36 15.5 0.2-2.0
Shining pondweed /
läik-penikeel
35 15.1 0.5-2.5
Clasping-leaf
pondweed/
kaelus-penikeel
25 10.8 0.7-1.3
Sago pondweed /
kamm-penikeel
8 3.4 0.5-1.5
Grassy pondweed /
hein-penikeel
7 3.0 0.4-1.4
11. Affective environmental factors
Water-level fluctuations throughout 4 periods
8 dry periods during 20th century
CaHCO3 on the leaves of submerged macrophytes
Renovations on shorelines
Fish like bream
NB! Submerged macrophytes are a very important structural
element in lakes and may markedly affect environmental
conditions of a lake by their ability to stabilize the clear-water
state.
12. ÜlemisteWater Treatment Plant
.. has been treating water since 1927
.. produces an average of 60,000 m3 of water per day
Average water consumption in 2013 was 93 litres per inhabitant
.. treats water by a treatment scheme often used world-wide
Ozone is used in the treatment process to improve the quality, odour,
colour and taste
Small amounts of chlorine is added in the drinking water, which is
effective protecton against bacteria as it travels through the network
Ülemiste WTP constantly develop new technologies and proceed to
improve our water drinking experience
13. Water treatment process
Surface water is gathered to Lake Ülemiste and directed to Water Treatment
Plant.
Raw water passes through screens and microfilters, which remove algae and
plankton from the water.
Water is led into reservoirs, where a mixture of ozone in air is injected into
the water to oxidize organic substances.
A water treatment chemical coagulant is added to clarify the water.
During the clarification phase particulate matter, chemical flocks and
precipitates are removed from the water.
Water passes through filters. In summer, dependent on the quality of raw
water coming into the plant, activated carbon may be added in order to
remove any remaining particles and to improve the taste of the drinking
water.
Chlorine is added to the water for disinfection purposes.
The water is directed to drinking water reservoirs, from which it is pumped
to the city water network in accordance with demand.
14. Drinking water quality
Drinking water quality is required to comply with “Quality and Control
Requirements and Analysis Methods for Drinking Water”
The water quality is monitored following the Drinking Water Quality
Monitoring Programme approved by the Health Board.
Drinking tap water is a growing trend
Raw water quality indicators are analysed once a day at the intake to the
treatment system
