Location
The area of Special Protection Area (36568,6 ha) lies in Kurpiowska plain and is situated south-west of Ostroleka to Chorzel and Wielbarka The site includes the valley of the Omulew River which flows into Narew River with its main tributary Plodownica.

Geological History and Landscape
The landscape of the area was formed during Scandinavian glacier that had been melting 15-10 thousands years ago. Flowing waters also formed sandar from the sand. Higher situated clusters which remained after the moraine are older. The bottom of the valley was filled with material brought by Omulew and Plodownica rivers in last thousands of years. The valley of both rivers is flat and separated by small dunes. The rivers are flowing slowly and they are strongly meandering. Along the riverbed (no more than 15 m width) you can admire natural flooded areas surrounded by mires. The valley covered by forest had been changed by agriculture in open landscape of well -preserved meadows and pastures five hundreds years ago. It remains till present.

Ecosystem
Ecosystem is strongly connected with small rivers and depends of yearly fluctuation of water level. The nature of the valley preserved its natural values compare to Mazowsze region. The rivers have never been regulated so they still are naturally active and variable. Their flooded surroundings and low peatbogs areas had been deforested last century and partly drained in 20th century. Remarkable part of the valley is extensively used as meadows and pastures (44%). Other agricultural areas cover 31%, forests (mostly coniferous) 24% of the area.

Flora
The area is mostly covered by water vegetation connected with mires and riverside water meadows flooded during spring. You can meet here rather poor pine forests overgrowing part of sandy soils in the valley. On the lower part of the Omulew river there are partially preserved old riverside riparian forests.

Fauna
Animal and vegetation world of this area is not documented well. You can find at least 19 species of breeding birds from Annex I Birds' Directive and 6 other migrating species mentioned in this annex. 12 birds' species are listed in Polish Red Book of Animals. The valley is an important habitat of Black Grouse, European Roller and Corn Crake. You can admire Common Cranes here in autumn (achieving number of 1320 individuals). During the migration the area is wonderful place for feeding ground for water-mud birds.

Threats

• discontinuance of using meadows and pastures;
• drainage of the area;
• rebuilding of the banks of the river which destroy natural habitat,
• cutting the riverside vegetation.

Nature conservation
The area is covered by following forms of nature conservation: 1st Protected Landscape Area of warminsko-mazurskie voivodeship.