During 1992 the environment agency used large amounts of clay from this area to strengthen and improve the flood defenses along the River Hull. After the clay had been removed islands were formed for breeding birds and a deep predator channel was excavated to prevent foxes and other mammals from reaching the islands. Some of the islands were graveled to attract breeding Little Ringed Plovers.

>> Species
Spring/Summer - As with the lagoons the marshes are attractive to waders
with most of the species seen on the lagoons also using the marsh.
The gravel islands attract breeding Little Ringed Plover but due to predation
the chance of any young surviving is generally poor.

Similar species of wildfowl also use the marshes with upto five pairs of nationally important breeding Pochards. Canada Geese and Ruddy Duck are usually present along with breeding Sedge and Reed Warblers.

Summer/Autumn - During this period as mud starts to become exposed around the islands the marshes become attractive to migrating waders. The same species as the lagoons are present and there may be much interchange between the lagoons and marshes depending on disturbance. The Ruff particularly likes to roost on the marshes and roosting birds can number over 100. In most years at least one Spotted Crake is attracted to the site but generally remains very elusive.

Winter - During the winter the marshes can be very attractive to wildfowl, especially Teal, however there is again much interchange between the different site locations and it is possible for the marshes to be almost birdless. The marshes are also a good place to find the scarce Jack Snipe, possibly the best time to connect with this species is when the edges of the marshes are frozen forcing the Jack Snipe to feed in the open, this is also the same for Water Rail which can be seen on the marshes but not as regularly as on the lagoons.