**2. Measured parameters and sampling points**

**1. Introduction**

378 Water Quality

is equal to 1600 m3

characterized by a capacity of over 1 million m3

**Figure 1.** Localization of the Turawa reservoir in Poland (Terra/Modis NASA).

reservoirs is about 4000 million m3

strongly decrease water pollution.

systems, and also for recreation.

(Opole Plain) (**Figure 1**).

respectively.

area, 20.9 km2

The resources of surface waters in Poland are relatively low, not equally distributed and

data). In order to improve the availability of water, quite a number of storage water reservoirs have been built in different parts of the country. Generally, water storage behind large dams is applied whereby the water is used for power generation, municipal water supply and flood control. Large storage reservoirs with controlled discharge provide larger amounts of water for periods of drought or low flow in the streams. In Poland, there are about 100 reservoirs

data). Unfortunately, this storage capacity has not been sufficient up to now. Moreover, the strong anthropopressure still observed makes that the water quality is not satisfactory in many cases. So, the efforts are being undertaken to increase waterretention and eliminate or, at least,

One of the larger water reservoirs in Poland is the Turawa reservoir, operated since 1948. It is used to drive a hydroelectric power plant, as a source of water for municipal water supply

The Turawa reservoir is situated between 50°42′27″ and 50°44′32″ north latitude and 18°04′51″ and 18°10′59″ east longitude in Mała Panew Valley, which is the part of Równina Opolska

It is situated on the Mała Panew river 16 km away from where it flows into the Odra river. The two other smaller rivers supplying the reservoir with water are the Libawa and the Rosa. The participation of these rivers in the surface water inflow to the Turawa reservoir is 87, 9 and 4%,

; length, 7.4 km; maximum width, 3.45 km; average width, 2.26 km; length of the

Morphometrical parameters of the Turawa reservoir are as follows: capacity, 95.5 hm3

/person—this is a third of the European average runoff per person (statistic

each. The total storage capacity of the Polish

, which constitutes about 6% of the annual runoff (statistic

of water, which

; surface

characterized by seasonal variability. The total annual runoff is about 57 km3

All typical parameters generally used to classify surface waters were measured, mostly in the recognized laboratories of water analysis by means of recommended procedures and some onsite using specialized measuring instrumentation. Laboratory-measured parameters are given in **Table 1** (parameters typical for water purity classification).

The measurements were made for 20 sampling points situated in the selected sites of the reservoir, the rivers flowing into the reservoir, namely the Mała Panew, the Libawa and the Rosa, the river flowing out of the reservoir, that is, the Mała Panew, and the small lakes in the neighbourhood of the reservoir. The points for on-site measurements and for collecting samples for laboratory analysis are presented in **Figure 2**.

Specific conductance was measured on-site using conductance metre whose accuracy was 0.1 μS cm−1. For oxygen content in water, the oxygen metre, enabling to carry out measurements up to the depth of 20 m, was used. Temperature was measured with the use of a mercury thermometer and also thermometers being integral parts of pH, oxygen and conductance metres. To determine water transparency, Secchi disk was applied. Bathymetric measurements were performed by means of a Lowrance sonar and an acoustic Doppler current profiler.


**Table 1.** Laboratory-measured parameters.

**Figure 2.** Location of the points for collecting samples for physico-chemical measurements: Geographical features: 1, water reservoirs: Jez. - lake and Zbiornik Turawski—the Turawa reservoir; 2, forests; 3, rivers; 4, roads; 5, dam.

Bathymetric measurements have shown that the reservoir is the deepest in the vicinity of the dam and the shallowest at the inflows of the rivers into the reservoir: the Mała Panew, the Libawa and the Rosa (**Figure 3**).

**Figure 3.** Bathymetric chart of the Turawa reservoir.

**Parameter Parameter (AAS)** Chemical oxygen demand (CODMn) Magnesium (Mg) Biochemical oxygen (BOD5) Manganese (Mn)

) Copper (Cu)

3−) Cadmium (Cd)

3−) Lead (Pb)

) **Parameter**

) Cyanides

**Figure 2.** Location of the points for collecting samples for physico-chemical measurements: Geographical features: 1, water reservoirs: Jez. - lake and Zbiornik Turawski—the Turawa reservoir; 2, forests; 3, rivers; 4, roads; 5, dam.

Total organic carbon Total Phosphorous Ammonia nitrogen Total dissolved matter

*Escherichia coli* PAH (total)

Nitrogen by Kjeldahl Phenol index Total nitrogen Anionic surfactants Fluorides Mineral oil index

) Zinc (Zn)

Total hardness (TH) Iron (Fe) Calcium (Ca2+) Cobalt (Co) Magnesium (Mg2+) Nickel (Ni)

Alkalinity (HCO3

Chloride (Cl−

380 Water Quality

Sulphate (SO4

Phosphate (PO4

− )

Nitrate (NO3

Sodium (Na+

Potassium (K+

Total alkalinity

**Table 1.** Laboratory-measured parameters.

−
