Successful bioremediation of oil-contaminated beaches requires maintenance of a sufficient quantity of growth-limiting nutrients in contact with the oiled beach material. A conservative tracer study was conducted on a moderate-energy, sandy beach on Delaware Bay to estimate the washout rate for dissolved nutrients from the bioremediation zone at different stages during the lunar tidal cycle. When an aqueous solution of the conservative tracer (LiNO3) was applied to the beach surface in the upper intertidal zone at the full moon spring tide, it was completely removed within one day. When it was applied at neap tide, however, the tracer persisted in the bioremediation zone for several days. The amount of nutrient remaining in the bioremediation zone was highly correlated with the maximum extent to which the treated area had previously been submerged by water at high tide: submergence resulted in nearly complete removal of dissolved compounds from the bioremediation zone. This high rate of nutrient washout was confirmed by daily monitoring of nutrient concentrations in the bioremediation zone during an oil-spill bioremediation field study that was conducted on a nearby beach.