Instability in a small hypereutrophic urban lake

Two summer intensive monitoring programs were conducted on a small Louisiana urban lake following restoration. Monitoring objectives were directed towards providing high resolution data needed to examine lake temporal and spatial variability. During the first year of post-restoration (1983), anaerobic conditions developed in the lake and a major fish kill (Ictalurus sp.) was observed. Total phosphorus concentrations at stations nearest the lake bottom were exceedingly high (>0.400 mg L^–1), suggesting the source of phosphorus was sediment release. Monitoring conducted in 1984 indicated the re-establishment of high benthic demand and internal nutrient recycling patterns. Mean phosphorus levels increased by more than 50% over the observed 1983 values, while dissolved oxygen concentrations demonstrated gradients from surface to bottom and were consistently below 2.0 mg L^–1 in the bottom waters.