Lake Wiritoa is a coastal lake with a maximum depth of around 20m. It is located in a 5ha parkland and has high recreational use. Horizons Regional Council monitors algal levels during the summer and undertakes quarterly water quality sampling (Trophic Level Index). The lake is usually safe for contact recreation in regards to E. coli, although due to elevated nutrient levels it can be susceptible to cyanbacterial blooms. The lake water quality has declined over the past decade due pastural farming releasing sediment and nutrients into the lake. The lake is classed as supertrophic (fertile and saturated in phosphorus and nitrogen) (www.lawa.org.nz).
Trout are released into the lake annually for recreational fishing. Perch and eels are also present (www.visitwhanganui.nz).