Long White Lagoon is located near the river mouth of the Waimatuku River and is the last in a small series of coastal lagoons and lakes situated along the coast between Invercargill and Riverton in the Southland region of the South Island of New Zealand. Long White Lagoon consists of a series of semiephemeral freshwater lakes which have been historically modified and drained for agricultural land reclamation. Long White Lagoon waters are in a hypertrophic condition with algal blooms commonplace. There are high fecal coliform levels. The lagoon is an important habitat for common bullies (Gobiomorphous cotidianus).