B2. Water



SURFACE WATER


ADMINISTRATION AND MONITORING OF SURFACE WATER

A basic artery of the river network in the capital city forms the lower reaches of the Vltava river. Near Lahovice, the most important tributary of the Vltava river on the Prague territory flows into it – the Berounka river. There are also several smaller water courses on the City territory, which flow into the Vltava River – the most important are creeks Litovicko-Šárecký, Dalejský and Radotínský on the left bank and Botič, Rokytka and Kunratický creek on the right bank.

The complete picture of surface water on the broken topography on the City territory is supplemented with numerous reservoirs and lakes. The total lenght of the minor water courses on the Capital City territory reaches almost 374 km, while about 226 km of which is administered by the City Prague. Waters in Prague are also formed by many larger and smaller ponds (e.g. Počernický pond, Lítožnické ponds as well as Šeberovské and Milíčovské ponds) and other types of water reservoirs with diverse features (the largest of them is Hostivařská Dam).

The care for small water courses and reservoirs on the City territory, which are administered by the Prague City Hall, is provided, for the Prague City Hall, by company “Lesy hl. m. Prahy“ (Forests of the Capital City of Prague). Monitoring water quality and the evaluation itself provides PCH.

Fig B2.1 : Yearly average flow rates at selected hydrometric profiles, 1986–2011

Source: ČHMÚ


WATER QUALITY

Enlistment of monitored profiles into classes according to CSN 75 7221 has been processed on the basis of data for two-year period 2010-2011. The evaluated indicators are classified into five groups (A, B, C, D and E). The indicator of the worst quality determines the entire group value. Then the group of the indicators of the worst classification value determines the overall classification of quality of water in a particular watercourse.

Fig B2.2 : Monitored profiles of surface water courses and resulting classes of quality

Source: RVP MHMP, Povodí Vltavy, s. p.

Note: Presentation of water quality in streams lines is only indicative.


DRINKING WATER


DRINKING WATER SUPPLY THROUGH THE PUBLIC WATER SUPPLY SYSTEM

The public water supply system in Prague and the drinking water treatment plants have been administered by Pražská vodohospodářská společnost, a. s. (PVS) since the beginning of year 1998. The joint stock company of Prague Water Mains and Sewerage Systems Co. (Pražské vodovody a kanalizace, a. s. = PVK) is the operator of the Prague’s water supply system.

Drinking water supplied for the public use is unobjectionable within the whole Prague territory and concerning the quality it fully meets the domestic and European standards in terms of physical, chemical, microbiological and biological.

In 2011 PVK, as in previous years, monitored the quality of the drinking water of nearly 6,000 samples. Of which over 75 % of samples were taken from the Prague‘s distribution network and the rest of the samples were taken from water treatment plants Želivka and Káraný which supply drinking water for Prague. 100 % of households got connected to the public water supply system on the Prague territory.

Water production: In 2011 there were produced 118 million m3 of drinking water in total. Out of this amount 16,1 million m3 went to parties purchasing out of the City territory. Compared to 2010, there were produced 3,5 million m3 of water less.

The most important share of the water produced for Prague supply comes from the Water Treatment Plant Želivka (73 % in 2011, resource is the water Reservoir Švihov), further the Water Treatment Plant Káraný (26 %, water resources are bank and artificial recharge filtration of water from the Jizera River). Both sources are located out of the City territory. The Water Treatment Plant Podolí (resource is the Vltava River on the City territory) has been used only as a back-up source and in 2011 it produced drinking water in August within the shutdown of a shaft conduit from Želivka (amount of less than 1 %, water source Vltava).

Loss of water due to leakages from the network in 2011 amounted to about 21 % (in 1996 46 %).

Water consumption: The specific consumption of drinking water in households has decreased by over 45 % since 1990. At present it is about 110 litres per capita and day.per capita and day.

Fig B2.3 : Development in the drinking water production

Source: PVK, a.s.


Fig B2.4 : Sources and distribution of drinking water in Prague

Source: PVK, a.s.


Fig B2.5 : Development of the specific consumption of drinking water in Prague

Source: PVK, a.s.


WASTE WATER


The downtown sewerage system in Prague was founded as an integrated sewerage system taking the mixed sewage and rainwater in the same pipes. The newly built housing estates at the Prague outskirts have separated sewerage systems, which do not mix together sewage and rainwater and take them away in separated systems. The housing estates sewerage systems are connected to main sewers of the Integrated Centralised Sewerage System. This system disposes waste water to the Central Waste Water Treatment Plant (CWWTP) on the Císařský Island in Bubeneč.

Besides this Central WWTP, there are other auxiliary (local) waste water treatment plants (hereinafter as the WWTPs) under operation on the City territory, which mostly serve for wastewater treatment of water from territories, which are located in the City outskirts and are not connected to the Prague Central Sewerage System.

At present roughly 99 % of the whole Prague population of approximately 1.24 million inhabitants is connected to the sewerage system. The operator of the greatest part of the sewerage system for public needs including the wastewater treatment plants in the City of Prague is the joint stock company PVK.

Fig B2.6 : Amounts of waste water treated in the CWWTP and in local WWTPs

Source: PVS, a.s.

Table B2.1 : Average concentrations
of pollutionin the CWWTP in 2011

Central WWTP Permitted Discharged
BSK5 [mg.l-1] 2 838,2 700
CHSKcr [mg.l-1] 13 245,1 4 184
NL [mg.l-1] 3 784,3 969
N-NH4+ [mg.l-1] 1 892,2 340
Pcelk [mg.l-1] 238,8 105
Nanorg [mg.l-1] 3 784,3 2 067

Source: PVS, a.s.


In 2011 the average daily inflow of waste water to the CWWTP was 327,585 m3. day-1, that is 3.79 m3.sec-1. In comparison with previous years, it proves the trend of moderate permanent suspension of decline. Slight increase in wastewater compared to 2010 was recorded rather in the connection with torrential rains, which flow into the integrated sewage system and is discharged to the CWWTP.


Fig B2.7 : Average flow rate of waste water in the CWWTP, 1996-2011

Source: PVS, a.s.


ACCIDENTAL CONTAMINANT SPILLS


In 2011 the Department of the Environment of the Prague City Hall (hereinafter as OOP MHMP) was active at 20 accidental spills and subsequently issued 26 administrative decisions. When the contamination originator was not known, then the OOP MHMP eliminated the emergency at the expenses of the Prague City Hall using professionally and technically capable legal or natural entities making business according to special regulations. In 2011 the contamination originator was not determined in 11 cases. In 2011 the Department of Water Protection of the Czech Environmental Inspection (CEI), Regional Inspectorate Prague dealt with 16 accidental contaminant spills on the City territory. In 9 cases the spill originator was not found.


FLOOD CONTROL MEASURES


Since 2005, flood protection of the internal city has been provided and consequently, works within other sub-stages are being done. In 2011 the works within stage 0007 – Troja were in progress, which, however, since the end of 2010 has already satisfied the criteria of the desired level of protection. There are still remaining parts of 22 Velká Chuchle within stage 0006 Zbraslav – Radotín to complete the entire system. After the completion (expected by the end of 2013), the capital will be protected against high water overflows of the Vltava river and the Berounka river at the level of the great flood in August 2002 with a reserve of +30 cm (with the exception of Zbraslav where the protection is designed for hundred-year water with a reserve of +30 cm).


CREEKS AND WATER WORKS ON THE TERRITORY OF PRAGUE

As at 31st December 2011 Prague’s territory as home to approx. 290 hectares of water bodies, out of that there were 182 lakes, 3 dam lakes and 37 retention reservoirs. The City of Prague, represented by the Department of the Environment of the Prague City Hall, managed 48 lakes, 4 water works and 32 retention reservoirs as at 31st December 2010. The most important basins are Dam Hostivař, Dam Džbán, Dam Jiviny and Počernický Pond. Prague’s territory is, besides the Vltava River and Berounka River, flown through by 360 km of smaller watercourses, out of them 249 km were managed by the City of Prague. The City of Prague also administered approximately 120 hectares of greenery along these watercourses. Among the most important and the longest creeks in Prague are Rokytka and Botič Creeks, other important creeks are Litovicko-Šárecký Creek, Dalejský Creek and Kunratický Creek.


RENEWAL AND REVITALISATION OF PRAGUE’S RESERVOIRS AND CREEKS


Fig B2.8 : Revitalization of Šárecký Creek (Prague 6, in front of Ruzyně Prison)

Source: RVP MHMP

Reservoirs and ponds in the possession of Prague are gradually being repaired, renovated and dredged (mud-removed) within the project Renewal and revitalization of Prague’s reservoirs, launched as early as 2003. Within this project in 2011 were realized: dredging (mud-removed) of retention reservoir Údolní in Braník, revitalization of Koztoprtský Pond in Čimice, dredging (mud-removed) and rehabilitation of banks of Hostivařská Dam and reconstruction and dredging (mud-removed) of Dolnomlýnský Pond in Kunratice as well as other projects began. A long-term project Revitalisation of Prague’s creeks has been in progress since 2007. Within this project in 2011 were initiated these activities: revitalization of Litovicko-Šárecký Creek in front of Ruzyně Prison and revitalization of Chodovecký Creek, other projects were under preparation.