In the aftermath of hurricane Katrina, when the levies broke around New Orleans, the Louisiana Department of Environmental Quality (LADEQ) was pressed into service. The agency relied on its inventory of water quality monitoring instruments to track where water was, and what areas were contaminated.

The department owns as many as 80 separate Hydrolab water quality monitoring instruments between all of its divisions, and they have typically been able to use Hydrolab instruments for 8 to 10 years. The instruments in the department's inventory include Minisonde 4a and Series 5 instruments with Hach LDO.

Under normal circumstances, this equipment is deployed as part of the state's ambient water quality monitoring network. This program is used for continuous monitoring to meet Clean Water Act requirements for monitoring surface water. Each year, monitoring stations are set up at approximately 130 sites statewide.

After the levies were breached, the ambient network was put on hold, and the program was adapted to handle post-hurricane impact assessment, with the department's focus turned to the areas impacted by the flooding. The instruments were deployed in a massive effort to take readings at between 40 and 50 sites along the Gulf Coast impact zone. Some existing sites were used, and new sites were established to characterize the direct and indirect effects the hurricane had, particularly to the Lake Pontchartrain area.

For the Series 5, in particular, department staff for the Water Quality Surveys Section appreciate that the instruments can be quickly calibrated, and that they hold their calibration well. They prefer the Series 5 with Hach LDO because they can be quickly redeployed, and the lack of a membrane means they require less maintenance than instruments using a Clark cell. In addition, deployment in a challenging environment such as a flooded city could also pose fouling problems with older technology, while Hach LDO is not affected.

The data gathered was necessary to profile the situation and assess the effects on surface water bodies. All these sites were visited at least twice, and some were decommissioned as the floodwater receded. Some sites are still active, and have been visited a dozen times or more. In all, department staffers have made up to 600 site visits, and counting.

"Obviously, our workload went way up," notes Chris Piehler of the Louisiana Department of Environmental Quality's Surveillance Division. "And there has never been a storm where the aftereffects have been monitored this closely."

Despite the impressive number of site visits, in uniquely challenging conditions, all Hydrolab instruments performed exactly as the LADEQ has come to expect - there have been no reports of any failures in the field. As a result of the quality of data provided by the Hydrolab sondes, plus the staff's efforts to ensure that data is accurate and verifiable when it is collected, there has been a very low rate of rejection of field data.

For more information about Hydrolab water quality measuring instruments, including the Hydrolab Series 5 with Hach LDO, visit the Hydrolab Water Quality Sensors page, or contact your sales rep today.