The mouth of the Isar river is one of Germany's last major near-natural river-mouth areas. With its riparian woodlands, numerous oxbows and gravel banks reflecting the typical character of a near-natural river mouth, the area represents a largely intact, seasonally flooded alluvial plain in an Alpine river mouth. It ranks as a great rarity in Central Europe from a conservation perspective and is classified as a biogenetic reserve. The core area comprises the course of the river Isar from Plattling to its mouth into the Danube, the Isar headland in this area, parts of the Danube headland and parts of the former floodplain with damp meadows, former riparian upland woodlands, peatland in silted-up meanders and 'Heißländ' (gravel beds formerly in the floodplain but now dry). Around 100 endangered plant species have been identified in this river valley. These include wildflower species such as lady bells (Adenophora liliifolia), blue flax (Linum perenne), shining spurge (Euphorbia lucida) and Gladiolus palustris. Besides various duck species, the birds that breed here include marsh harriers (Circus aeruginosus), black kites (Milvus migrans) kingfishers (Alcedo atthis) and bluethroats (Luscina svecica).

The objective of the project is the conservation and restoration of a largely intact and near-natural alluvial floodplain, the regeneration of alluvial plain ecosystems with near-natural riparian woodlands, floodplain scrub vegetation, forb stands, water plants and reed communities, with open gravel- and sandbanks. Following restoration measures, the parts of the project area within the flooding zone are to be left to evolve naturally as far as possible. Away from the flooded areas, the plans are to conserve and develop the semi-natural anthropogenic habitats which have emerged in this cultural landscape characterized by farming and extensive land use.