All five lakes - Kagul, Kugurlui, Yalpug, Katlabugh and Kitai – are relatively shallow in relation to their area because they are actually limans (flooded river valleys) with one or more rivers flowing into them and comprising part of the natural Danube floodplain before it was embanked.
Lake Kagul is comma-shaped, with the tail end formed by the Kagul river valley. The lakes are connected directly to the Danube via the Viketa canal and to Lake Kartal by the Zarza and Luzarsa channels.

Lake Kartal is located on the Danube floodplain between the southern ends of Lakes Kagul and the western ends of Kugurlui. It is connected directly with the Danube via the Orlovsky and Prorva channels and is connected in the southern part with Lake Kugurlui by the Tobachello channel.. Lake Kartal is very shallow and flat.
Reeds and sedges cover the shores of Kugurlui. Three channels (Skunda, Canal km 105 and Repida) connect the lake with the Danube. Lake Yalpug is connected with Kugurlui by an open channel through a narrow artificial sand causeway constituting the Reni-Izmail road. In the upper part of Lake Yalpug the valley transforms into a floodplain.

Lake Katlabugh has shores comprised of exposed bedrock; in the south the shores are marshy and made up by the reedbeds. The Bolshoi Katlabugh and Maly Katlabugh rivers that flow into the lake are shallow and dry out in summer. Lake Safyani, part of the Katlabugh lake complex, has a length of 6.5 km and an average width of 500 m (maximum 1 km). The water surface area (at 2.5 m depth) is 4.2 km2. A thick layer of silt covers the bottom. Water transparency varies between 0.1-0.5 m. The southern shore is marshy and is connected with the Stara Nekrasovka reedbeds and lakes (called Lung). When the Danube water level increases by more than 2 m, the water penetrates into the lake directly through the Stara Nekrasovka reedbeds. The whole reedbed complex is embanked and managed (as all the other lakes) by a sluice at the Danube riverbanks, and there is a connection to the Katlabugh Lake. Two channels (Obshchestvenny and Zhelyavsky) connect Katlabugh with the Kislitsy arm of the Danube. The first channel is also connected to Lake Safyani.
Lake Kitai consists of a southern and a northern part, divided by a 600 m-long causeway. The shores are comparatively high. There are two rivers (the Aliyaga and Kirgizh-Kitai) flowing into the lake in the north. These rivers dry out in summer. The lake is connected with the Kislitsy arm of the Danube by the Kofa channel.

Lake Kartal was listed as a wetland of international importance under the Ramsar Convention on 23 November 1995. The area covers 500 ha and is important for breeding, moulting, migrating and wintering birds (up to 40,000 individuals). There are 32 bird species listed from the Ukrainian Red Data Book (RDB), such as glossy ibis Plegadis falcinellus, squacco heron Ardeola railloides, ferruginous duck Aythya nyroca, and black-winged stilt Himantopus himantopus. Furthermore, the site supports three globally threatened species: pygmy cormorant Phalacrocrax pygmeus (70 pairs, about 1% of the European population), spoonbill Platalea leucorodia (150 pairs, about 3% of the European population) and red-breasted goose Branta ruficolis.

Lake Kugurlui (6,500 ha) was also designated as a Ramsar Site on 23 November 1995. There are 57 bird species listed for the Ukrainian RDB, including five globally threatened species: pygmy cormorant Phalacrocorax pygmeus (about 80 breeding pairs, 1% of the European population), spoonbill Platalea leucorodia (150 pairs, about 3% of the European population), ferruginous duck Aythya nyroca, Dalmatian pelican Pelecanus crispus, and white pelican P. onocrotalus. During migration and winter, the site supports up to 30,000 birds, such as white stork Ciconia ciconia, and many geese and duck species including white-fronted goose Anser albifrons, Mallard Anas platyrhynchos and Pochard Aythya ferina.