Lead in the Bolsa wetland of southern California, USA: Effect of flood control channelization

The distribution of lead in sediments of an estuary receiving flood control discharge has been examined. Relatively high concentrations of lead with a mean value of 64 ppm were found within the outer portion of Bolsa Bay which receives flood control runoff. Significantly lower concentrations of lead with a mean value of 9 ppm were found within the impounded inner portion of the bay which does not receive flood control discharge. On the basis of our findings we recommend that flood control runoff no longer be discharged directly into estuaries but that discharge be either rerouted to ocean outfalls or reclaimed and used for agricultural and industrial purposes.