Copper toxicity in marine environments has been shown to be influenced by a variety of water parameters which can affect the ratio of ionic to complexed copper species in the water column. Dissolved organic carbon (DOC) concentration has been previously shown to correlate negatively with observed copper toxicity in marine and estuarine environments. This is presumably due to increased complexation of ionic copper to DOC complexes under higher DOC concentrations, thereby decreasing the degree to which the toxic (ionic) form of copper is found in the water column. A previously described DOC-based model for estimating copper toxicity in marine environments was applied to samples collected from a copper-impaired marine environment (Shelter Island Yacht Basin (SIYB), San Diego, CA). Site-specific objectives (SSOs) derived from the model were 7.5 _g/L and 4.8 _g/L for acute and chronic copper concentrations, respectively. The resultant estimation of copper toxicity showed good agreement with observed copper toxicity from a previous study conducted in SIYB (DOC-based WER=1.55 compared with WER=1.36 in previous studies). The results of this study show that the DOC-based model may be applied to estimate copper toxicity in SIYB, as well as to derive site-specific water quality objectives for dissolved copper in the basin.