Life in the catchment and lagoon
Waituna Lagoon represents an exceptional example of a largely unmodified coastal lake-type lagoon within a largely intact coastal wetland system.
The lagoon contains important habitat for resident and migratory birds including nationally critical and endangered species. The aquatic community includes a ruppia-dominated macrophyte community not well represented elsewhere and a number of native fish species, in addition to a valued recreational trout fishery. In surrounding areas the presence of several alpine and sub-alpine species at sea level is of botanical interest. Lagoon levels have traditionally been managed by opening the lagoon to the sea to increase access for sea-run trout and improve local drainage.
The lagoon and surrounding wetland form at the confluence of several small creeks, the three most substantial of which are Waituna Creek (catchment area 10,604 ha), Moffat Creek (1,733 ha) and Carran Creek (2,871 ha). Historically these waterways fed into the lagoon, which increased in depth until it overtopped the gravel barrier beach, breaching it and emptying the lagoon.
This natural regime would have involved the lagoon rising as much as 4m above sea level before emptying.