Fecal coliform bacteria continue to be the most common pollutant in Louisiana s rivers and streams, followed by low dissolved oxygen concentrations and nutrients. Sources of bacteria include sewage discharges from municipal treatment plants, subdivisions, trailer parks, and apartment complexes. Agricultural runoff generates oxygen-depleting substances and nutrients. In estuaries, oil and grease, nutrients, and bacteria are the most common pollutants.
Hydrologic modification impacts one surveyed wetland.
The quality of water in the State s major aquifer systems remains excellent. Of special concern, however, are the shallow aquifers and the water-bearing zones that are not used as major sources of water. These strata contribute significantly to the water balance of the deeper aquifers, but the shallow aquifers are increasingly threatened. Currently, most reductions in nonpoint source pollution result from cooperative demonstration projects due to a lack of regulatory authority in Louisiana to control nonpoint source pollution. These projects have demonstrated alternative rice farming management practices to reduce sediment and nutrients in the Mermentau River Basin, advocated lawn care management to reduce erosion and runoff in the Bayou Vermilion watershed, and reduced fecal coliform concentrations in the Tangipahoa River by implementing septic tank and dairy waste lagoon education programs and upgrading municipal waste-water treatment systems.