Phase 2 Monitoring for LT2 Enhanced Surface Water Treatment Rule (LT2)
Surface water-using Public Water System (PWS) required to monitor for Cryptosporidium under Phase 2 of LT2 need to understand the importance of knowing that both Cryptosporidium and Giardia are present in their source water. The concentrations at which they are present determines the risk, whether high, low, or somewhere in between. Phase 1 LT2 monitoring results were more than 93% zeros thus failing to show the relative risk or to provide useful information for watershed or treatment system management. Reasons for this failure were that sample volumes were too small in most cases to allow detection, and that recovery efficiency was not measured for each sample to permit calculation of concentration...essential for any quantitative use of the data, in particular, comparisons between sampling times or between different sites. The failure to analyze samples for both Cryptosporidium and Giardia also greatly limited the value of the Phase 1 LT2 data.
All water supply agencies and regulatory agencies must understand the clear evidence that human and animal sources of both Cryptosporidium and Giardia are present in watersheds everywhere. Published data on the universal distribution of organism sources, the consistency of their presence, and the occurrence of outbreaks dictate that concentrations of both organisms would be clearly defined by use of larger samples and by measuring and accounting for recovery efficiency for each sample.
The underlying goal of LT2 Phase 2 monitoring is to collect reliable data to define the true spectrum of risk corresponding to Cryptosporidium & Giardia concentrations in PWS surface water sources. Data to achieve this goal can be produced by straight-forward, practical, and modest-cost adjustments in monitoring as follows: 1) increase sample volumes appropriate to each sampling site; 2) require internal recovery measurement to be included for every sample analysis; and 3) calculate and use concentrations to establish risk characteristics for each source. These data would provide for ranking risk and as appropriate for catchment and treatment system management.
Clearly, the approach to monitoring needs to be site specific taking into account background watershed and water quality characteristics. For more specific information or answers to any questions, contact the author at (510) 545-3645 or by email.
Ref. 1: Environ Sci Technol 47(9): 4029–4038 (http://dx.doi.org/10.1021/es4006509)
Ref. 2: http://www.water.epa.gov/lawsregs/rulesregs/sdwa/lt2/upload/cryptodatacleaned1.csv
Ref. 3: Environ Sci Technol 47(18):10145–10154 (http://dx.doi.org/10.1021/es4027503)
All water supply agencies and regulatory agencies must understand the clear evidence that human and animal sources of both Cryptosporidium and Giardia are present in watersheds everywhere. Published data on the universal distribution of organism sources, the consistency of their presence, and the occurrence of outbreaks dictate that concentrations of both organisms would be clearly defined by use of larger samples and by measuring and accounting for recovery efficiency for each sample.
The underlying goal of LT2 Phase 2 monitoring is to collect reliable data to define the true spectrum of risk corresponding to Cryptosporidium & Giardia concentrations in PWS surface water sources. Data to achieve this goal can be produced by straight-forward, practical, and modest-cost adjustments in monitoring as follows: 1) increase sample volumes appropriate to each sampling site; 2) require internal recovery measurement to be included for every sample analysis; and 3) calculate and use concentrations to establish risk characteristics for each source. These data would provide for ranking risk and as appropriate for catchment and treatment system management.
Clearly, the approach to monitoring needs to be site specific taking into account background watershed and water quality characteristics. For more specific information or answers to any questions, contact the author at (510) 545-3645 or by email.
Ref. 1: Environ Sci Technol 47(9): 4029–4038 (http://dx.doi.org/10.1021/es4006509)
Ref. 2: http://www.water.epa.gov/lawsregs/rulesregs/sdwa/lt2/upload/cryptodatacleaned1.csv
Ref. 3: Environ Sci Technol 47(18):10145–10154 (http://dx.doi.org/10.1021/es4027503)