| Water |
 |
Navigation | Sector indicators in this report | Global indicators | Issue links | SoE Homepage |
Water State page
|
Surface water quality If comparing the quality of small streams in Prague a short distance upstream of the confluence with the Vltava River between 1993 and 1997, it is possible to conclude that the water quality remains basically the same, and any improvement or deterioration is essentially insignificant. All monitored small streams in Prague fall into the 5th, i.e. the worst water quality class. The Vltava River maintained Class 4 in the Vrané and Podolí profiles, but the Vltava - Libeice and Berounka - Lahovice profiles continue to be Class 5. As to Group A criteria (oxygen regimen), the Vltava River (at Vrané Monitoring Profile) dropped to Class 2 in the following criteria: DO2 (dissolved oxygen) and COD(Cr) (chemical oxygen demand - dichromate). The DO2 value showed some improvement at one profile on the Botie Creek and another on the Dalejský Creek. On the other hand, twelve monitoring profiles on small streams showed a deterioration in this respect. As to BOD (biological oxygen demand), the Dalejský, árecký, and Rokytka Creeks dropped one class down, the Motolský Creek (Motol profile) by two classes. The Dalejský, Stodulecký and Botie Creeks improved to Class 4 in the COD(Cr) parameter. See map of monitored sites and water quality parameters in 1996-97
There have been no changes in Group B (chemical criteria - basic). The overall classification is practically consistent with the classification based on the NO2 (nitrites) parameter; as this is the least favourable classification, it also determines the overall classification of monitoring profiles. Some of the monitoring profiles fall into the worst class as well because of other criteria, for example ammonia (KU00, SP06 profiles), total phosphorus (DL04, KU00, SP06 profiles). However, it is necessary to mention a two-class improvement in the NDS (non-dissolved solids) parameter of Profile SP01. As to Group C criteria (chemical criteria - supplementary), non-polar extractable substances (NES) were monitored once again at monitoring profiles on the Vltava and Berounka Rivers. The substances indicate a pollution of oil hydrocarbons, and for the most part are washed off road and street surfaces. There is not enough information for an evaluation of the Vltava and Berounka Rivers; as to creeks, there was a deterioration in the NES parameter on Profiles BO02 and RO01. On the other hand, Profile SP01 showed an improvement by one class in this respect. As to Group D (heavy metals), two of the monitoring profiles exhibit an improvement. Particularly worth mentioning is the improvement shown by the Vltava - Vrané monitoring profile insofar as the concentration of mercury is concerned; judged by heavy metals alone, the monitoring profile would even comply with Class 1 requirements. The Vltava and Berounka Rivers are also monitored for chromium and nickel (which are not monitored in small streams). The árecký Creek showed a higher content of arsenic in two of its monitoring profiles (SP06 and SP07), bringing its classification to Class 2, which also affected the overall classification of the two profiles in Group D. Group E (biological and micro-biological
criteria) did not show any changes insofar as the FEC (fecal
colliform bacteria) parameter in the Vltava and Berounka Rivers are
concerned. Analyses of small streams in Prague use a different
criterion, COL, (colliform bacteria) which includes fecal bacteria.
There were changes in the parameter on the árecký Creek
(improvement to Class 4 on Profile SP03, deterioration to Class 5 on
Profile SP07). The Vltava - Podolí monitoring profile is also a place
where raw water is pumped into the water treatment plant in Podolí.
Practically all water quality parameters are adversely affected by
the Berounka River (the Vltava - Berounka confluence is just a short
distance upstream). Between Vrané and Podolí, the yearly average
number of fecal colliform bacteria in one milliliter of water climbs
from 14.3 to 41.4. The deterioration is not due solely to the
Berounka River the yearly average value of which is 22.4; the
biological contamination also results from the municipal sewage
collection system. According to the CSN 757214 Czech National
Standard, the Vltava water in Podolí is characterized as raw water
unsuitable for drinking and usable in exceptional and justified
cases only. The water supply network of Prague makes use of three principal sources - Káraný, Podolí, and Zelivka. Tapped to the water system are roughly 99 % of people living in Prague. Since the beginning of 1998, the public water supply system of the City of Prague, including drinking water treatment plants, is currently operated by Prazská vodohospodárská spolecnost, a.s. (Prague Water Management Authority). The water pipeline system is operated by Prazské vodovody a kanalizace, a.s. (Prague Water Supply and Sewerage Company). The
Praha - Podolí drinking water treatment plant draws raw
water from the Vltava River, which has not hitherto been declared a
drinking water source adversely affecting the raw water quality.
Shares
of the different water treatment plants in the aggregate drinking
water production
Source: Prazské vodovody a kanalizace a.s. In addition to the three major facilities mentioned above Prazské vodovody a kanalizace also operates the so-called Industrial Water Supply Pipeline, which draws water from the Vltava River (Libenský ostrov) and delivers supply water to industrial plants in the northeastern part of the city. Due to a complex terrain configuration of Prague, the distribution of water in the city is a very demanding task. The total length of the water supply system operated by Prazské vodárny is 3,099 km with water supply connections accounting for a further 642 kilometers. There are also 40 pumping stations and 65 water reservoirs with an aggregate capacity of 840,000 m3. Owing to its age, corrosion, conditions under which the piping is buried in the ground, materials used in the piping and other factors, the water distribution network shows a high failure rate. Of the whole length of the water supply system in Prague 26.1 per cent, i.e. 810 km is more than 60 years old. In 1997 the company produced a total of 200 Mm3 of treated water of which drinking water accounted for 198 Mm3. Customers outside the city limits account for approx. 14.5 Mm3. Drinking water quality Drinking water quality is assessed using the CSN 75 7111 Czech National Standard (Drinking Water). The standard is based on a WHO (World Health Organization) directive and is fully compatible with other European standards. It is the Káraný plant which in the opinion of both experts and laymen supplies the best water to Prague. This is due partly to the raw water quality, partly to the environmentally friendly treatment process being used. The drinking water produced in Káraný consists partly of naturally filtered water, partly of artificially filtered water, partly artesian water free of iron, and partly water from springs located along the Lower Labe River. The artesian water is a deep-seated groundwater, and some of it is bottled as table water. Artificial or natural infiltration allows to obtain water the quality of which is virtually the same as that of groundwater. There are, however, some difficulties being encountered in connection with the artificial filtration. Microbes and nutrients find their way into filtering tanks especially during the vegetation season. This is why a pre-treatment process consisting in optimization tests was tried on the raw water drawn from the Jizera River. In 1997 the project reached a pilot phase. In terms of its capacity the Podolí Treatment Plant is the second most important source of drinking water for Prague. However, its importance lies mainly in its location (almost in the centre of consumption) and in its inexhaustible raw water supply. In terms of its capacity the Zelivka drinking water treatment plant is the most important drinking water source for Prague and a part of Central Bohemia. Between 1991 and 1995 an extraordinary proliferation of phytoplankton was observed in the raw water reservoir during spring months when the water level in the reservoir was lower. Whilst the phytoplankton affected the drinking water quality it never caused the limit of applicable parameter (biology - dead organisms) set forth in the CSN 75 7111 Czech National Standard (Drinking Water) to be exceeded. In March 1997 an increased content of iron was discovered in three samples. Prazské vodárny immediately took remedial measures. The increased content of iron is attributable mainly to corrosion of metallic water pipes without any inner lining combined with a very low flow rate caused by an ever-decreasing water consumption. All the other samples taken during 1997 were in compliance with the CSN 75 7111 Czech National Standard (Drinking Water) insofar as relevant chemical, bacteriological, or biological parameters monitored by the Municipal Hygienic Institute of the City of Prague are concerned.Comparison of water treatment plants and water supply
network from the viewpoint of selected parameters
|
What is
the general situation with the ISSUE ? 
| There is also information related to this issue in the following sections of the report | ||
|
||