The medium depth aquifer is located in the altered and karstified Sarmatian limestones, locally covered by bentonitic clay. The aquifer is locally unconfined, in the zones where it is covered by loess deposits, or locally confined, in zones where it is covered by clayey loess deposits . The aquifer is supplied from the Bulgarian territory, where the whole structure is at higher elevations, and by recharge from precipitation. The aquifer discharges to the east to the Black Sea, and to the Danube - Black Sea canal (Fig. 28.3).
The water table in the abstraction wells from the Sarmatian aquifer is, usually, mainly ascending. The pumping rates at the installation are between 3.33 and 6.25 l/s, the estimated average hydraulic conductivities being between 3.48 and 6.90 m/day, corresponding to 16-30 m thick total screened intervals.
Groundwater from the Sarmatian aquifer exceeds the standard for nitrate content (80 mg/l) and for filtrate residual (over 2,000 mg/l), and the standard for total coliforms and fecal coliforms as well.
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