The site contains the channel and valley of the Bug river between the Krzna river tributary and the Zegrzyñski reservoir (260 km), with adjacent extensive dry pastures. The whole area floods in spring. There are some swamps and mires at the mouths of tributaries entering the Bug. The river channel is generally natural, not too modified by man, so there are numerous bare sand islands and others overgrown with ruderal herbs or willow Salix scrub. Elsewhere there are also local remnants of willow or poplar Populus scrub. On the lowest river terrace there are numerous oxbow lakes, differing in size, depth and extent of aquatic vegetation (Potamogeton, Lemna).
The site supports more breeding Charadrius hiaticula than any other inland site in Europe.
Pressure/threats to key biodiversity
Threats include dam-building, conversion of meadows to arable land, building of infrastructure for recreation, and reduced numbers of cattle with consequent reductions in extent of pasture.
National Partial International None133 ha of IBA covered by Nature Reserve (£êg Dêbowy, 133 ha). 2 ha of IBA covered by Nature Reserve (Skarpa Mo³o¿ewska, 2 ha). 64 ha of IBA covered by Nature Reserve (Wydma Mo³o¿ewska, 64 ha). 33,000 ha of IBA covered by Landscape Park (Nadbu¿añski, 53,680 ha). 15,000 ha of IBA covered by Landscape Park (Podlaski Prze³om Bugu, 30,904 ha). 17,500 ha of IBA covered by Protected Landscape Area (Nadbu¿añski, 55,300 ha).