At many places in the Polders, in the Oder foreland but also beyond the Hohensaaten-Friedrichsthaler Wasserstraße there are oxbow lakes of the Oder, which has been regulated for 100 years. The Oder River, which once meandered freely through the lower Oder valley, was brought together at the eastern edge of the valley at the beginning of the 20th century, the loops and loops of the river separated by summer dykes and degraded to oxbow lakes and oxbow lakes. During the winter months, the Wet polders (Criewener and Schwedter Polder and Fiddichower Polder) these oxbow lakes and oxbow lakes are flooded, and the water can exchange. With the drainage of the water in the spring and unfortunately also with the artificial pumping out of the water that does not drain away by itself, the oxbow lakes become bodies of water again without connection to the neighboring rivers after the inlet and outlet structures are closed.
In the Dry polder (Lunow-Stolper Trockenpolder, Friedrichsthaler Polder) these winter floods do not exist and therefore no contact of the oxbow lakes and oxbow lakes with the Oder river water. Fresh water comes into the oxbow lakes only through seepage water through the dike feet or through rainwater. Incidentally, this leads to different aquatic fauna, especially fish fauna, in the oxbow lakes of the dry and flooded polders, which scientists are continuously investigating.
At the edge of these waters, the high inflorescences of the marsh milkweed fall as early as the end of April (Euphorbia palustris) with their intensely yellow colored bracts. In mid-May, the white flower spots of the water crowfoot (Ranunculus aquatilis) adorn the scour (natural depression of the watercourse), soon accompanied by the very inconspicuous inflorescences of the spawning weeds growing submerged in the water. In early summer, the pink-red inflorescences of the magnificent swan flower are on the edges of the water (Butomus umbellatus) to admire. Some pools are in the summer with dense stocks of the white water lily (Nymphaea alba) covered, occasionally by the yellow flowers of the pond rose (Nuphar lutea) interspersed. The yellow flower groups of the meadow alant provide a colorful picture (Inula britannica), the blue flower spikes of the long-leaved blue loosestrife (Pseudolysimachion longifolium) who have favourited cat’s tail tiny pink flowers (Leonurus marrubiastrum) and the white inflorescences of the willow-leaf yarrow (Achillea salicifolia) mixed with lots of grasses and sedges.