A stagnant 17-km long freshwater lake, located between Haringvliet (024) and Biesbosch (051), bordered by reedbeds and grassland polders. The water-level varies, depending on the river supply. This site, together with site 024, formed part of a single, larger site (former site NL047) in the previous international IBA inventory (Grimmett and Jones 1989).
The site is especially important for roosting geese from surrounding feeding areas, although there have been few counts of numbers. The average seasonal peak number of waterbirds during 1992-1996 exceeded 20,000.
Pressure/threats to key biodiversity
The main problems are heavily polluted sediments and nutrient pollution.
National Low International None235 ha of IBA covered by Natural Monument (Esscheplaat, Zeehondenplaat en Sasseplaat, 235 ha). 30 ha of IBA covered by Natural Monument (Esscheplaat, Zeehondenplaat en Sasseplaat II, 30 ha). 40 ha of IBA covered by Natural Monument (Hoogezandse Gorzen, 40 ha). 55 ha of IBA covered by Natural Monument (Oosterse Slobbegorzen, 55 ha). 97 ha of IBA covered by Nature Reserve (Esscheplaat, 97 ha).
BirdLife International (2020) Important Bird Areas factsheet: Hollands Diep. Downloaded from
http://www.birdlife.org on 21/09/2020.