Guam EPA keeps interim action levels in place while staff and GWA discuss implementation details

The Guam Environmental Protection Agency Board of Directors confirmed that its prior action adopting interim action levels remains in effect while staff and water utilities work through implementation questions, board members said Thursday.

Board members said they will not undo last month’s vote immediately but asked agency staff to meet with the Guam Waterworks Authority and other providers to clarify how monitoring, entry-point sampling and public-notification timelines will be implemented.

Board legal counsel cautioned the board that any change to the adopted rules must be supported in the administrative record and that substantive amendments could require restarting portions of the rulemaking process. “Anything that you guys do, it has to be supported in your in your record,” counsel told the board during the discussion.

The board discussion focused on several operational issues raised by GWA staff during public comment. GWA representatives said they provided voluntary monitoring data going back years and are concerned that because they already have test results the agency will require them to begin required notifications and other compliance steps sooner than providers that did not previously sample. GWA staff said that raised questions of fairness and consistency across all public water systems.

GWA also raised concerns about where samples will be collected. The proposed interim action-level rules call for measuring concentrations at an entry point to the distribution system; GWA staff said several of their wells blend into reservoirs and that sampling at the well does not always reflect the concentration delivered to customers. Agency staff responded that the rule’s entry-point requirement remains in effect, and that where water is treated or blended, the entry point (for example the reservoir outlet after treatment) will be used for the required samples and the running annual average calculations.

Agency staff described the monitoring calculation process: previous monitoring data (including samples from the past four quarters where available) can be used to calculate a running annual average for each well or entry point. If the running annual average exceeds the interim action level, a water system would be subject to the rule’s tiered notification requirements.

Board members and GWA also discussed the numeric interim action levels that appear in the proposed rule: a lower threshold (0.2) that triggers longer-term actions and a short-term threshold (0.5) that prompts rapid public-notification steps. Agency staff said the thresholds were set after risk assessment guidance and peer state examples were considered. One board member noted that implementing testing and treatment (for example installing granular activated carbon systems) will be costly and may require multi-year planning; GWA estimated work on affected wells could take about one year in at least some cases.

Rather than rescind the prior vote, the board said it will keep the adopted interim action levels in place and direct agency staff to continue discussions with GWA and other water providers to recommend implementation dates, clarify sample point definitions, and consider whether targeted amendments are warranted. The board did not take a new formal vote on changing the adopted levels during the meeting.

Board members said the follow-up work should occur at staff level and return to the board with recommendations rather than reopening full rulemaking immediately. Several members emphasized the goal of protecting public health while avoiding sudden, inequitable burdens on individual providers.