The refuge covers a long part of natural Bug valley, between Polesie Wołyńskie and Polesie Podlaskie, which is at the same time the border between two countries between Gołębie (where Bug river crosses the border) and Terespol.
The river in the refuge part is located in a deep riverbed, with many meanders and oxbowlakes, as well as few meters’ tall embankments. Significant part of the valley is made of meadows and degraded forests and willows. There are also farmlands. In the refuge, there can be found at least 22 species of birds mentioned in the 1st attachment to Birds Directive, including 9 from Polish Red List of Endangered Species. At least 1% of the population of following species spend their nesting period and produce their clutch here: Montagu’s harrier (Circus pygargus), white stork (Ciconia ciconia), corn crakes (Crex crex), white-backed woodpecker (Dendrocopos leucotos), whiskered tern (Chlidonias hybrida), black tern (Chlidonias niger), white-winged tern (Chlidonias leucoptera), kingfisher (Alcedo atthis), common sandpiper (Actitis hypoleucos), common redshank (Tringa totanus), black-tailed godwit (Limosa limosa). The refuge is also inhabited by 5% of country’s population of sand martins (Riparia riparia), which makes up around 10 thousand pairs. In addition, 8 species of migratory birds were spotted in the refuge, which are also listed in 1st attachment to Birds Directive. There are also numerous examples of botaruses, western marsh harrier (Circus aeruginosus), bluethroats (Luscinia svecica) and barred warbler (Sylvia nisoria). Apart from rare bird species, numerous animals and plants can be found here, including one type of vascular plant, mentioned in 2nd attachment to Habitats Directive.