Human activity in the bay's watershed produces a complicated array of toxic compounds, many of which are routinely discharged, spilled, or washed into the estuary in a water solution or suspension. Water and sediment-dwelling species can accumulate toxic compounds, affecting the composition and health of living estuarine communities.
Toxicants can cycle back and fourth among the water, sediment, and tissues of living organisms.
Measurement technologies, which are complex and expensive, impose another layer of uncertainty on our state of understanding. In addition some water quality limits are set below analytical detection limits, further complicating the issues. Typically, levels of toxic contaminants in open bay waters are below detection limits. In sediments , Ward and Armstrong also showed elevated contaminant concentrations in regions of runoff, inflow, and waste discharges. In tissue , various studies have measured contaminants in a variety of species.