To Dose, or Not to Dose? The Orthophosphate Paradox

By Emily Remmel, Director of Regulatory Affairs, NACWA

Emily Remmel headshot

In the wake of the public health crisis that unfolded (and continues to unfold) in Flint, Michigan, EPA is critically thinking about how to modernize the Lead and Copper Rule (LCR) framework both in terms of protecting public exposure to lead in drinking water as well as the manner of replacing the thousands of lead service lines buried across the country. The U.S. Environmental Protection Agency’s (EPA) continues to slog through the process of revising and updating the three-decade-old LCR.

Under the previous Administration, EPA penned a final rule and published it in the Federal Register on January 15, 2021 that established effective dates and future compliance dates for drinking water systems. This updated LCR seemed to be a done deal; however, the Biden-Harris Administration—through a “regulatory freeze”—pulled the rule back for a closer review and to potentially revise the rule yet again.

The current quasi political-regulatory review mainly involves the concerns of drinking water systems and the Safe Drinking Water Act. However, a lesser-known issue—the mandating of orthophosphorus as a standardized, national optimal corrosion control treatment (OCCT) method—has unearthed serious Clean Water Act concerns within the clean water community.

Traditionally, public water systems have been granted inherent flexibility under the Safe Drinking Water Act to select the corrosion control technology that would be most effective at mitigating lead leaching from aging pipes based on local water quality parameters. In a true one-water framework, upstream drinking water utilities should be able to consider and make flexible management decisions that are protective of public health as well as protective of downstream water quality.

The Agency, in its 2020 proposed rule, stated “the use of orthophosphate for corrosion control can increase phosphorus loading to wastewater treatment facilities… (which) may be a concern for wastewater systems with phosphorus discharge limits or for systems that discharge into water bodies where phosphorus is a limiting nutrient” (84 Fed. Reg. 61693). Yet, EPA also restricts drinking water systems from considering their downstream wastewater treatment neighbors’ potential increased cost impacts or water quality degradation, stating, “water systems conducting corrosion control studies would not be able to rule out orthophosphate simply based on the increase in loading to wastewater treatment facilities.”

The required use of orthophosphate will undoubtedly require downstream wastewater treatment plants to treat effluent to greater levels at greater costs in order to comply with stringent Clean Water Act nutrient requirements. This will be particularly true of those wastewater treatment plants in arid and semi-arid areas where clean water utilities discharge into low flow or effluent dominated streams.

Upon review, EPA should address this nutrient paradox. Nutrient pollution is a known driver for surface water quality degradation, and many communities are witnessing an increase in eutrophication, algal blooms, and subsequent hypoxic zones due to excess phosphorus and nitrogen from point and nonpoint sources contributions.

Now that EPA is taking a harder look at the LCR, the clean water community urges the Agency to recognize this critical regulatory issue through the lens of a holistic, one water approach that transects both the Safe Drinking Water Act and the Clean Water Act.

EPA could reinstate the inherent flexibilities traditionally granted to drinking water utilities to determine through best professional judgment the right OCCT on a case by case basis. Alternatively, it could encourage state regulatory authorities to provide downstream clean water utilities with Clean Water Act regulatory flexibility. For example, it could encourage them to consider the development of a variance or conducting a use attainability analysis (UAA) to account for increased phosphorus concentrations associated with the LCR, where necessary to enable utilities to meet Clean Water Act permitting requirements.

It is possible to provide critical public health protections through drinking water treatment without sacrificing downstream environmental and water quality. EPA has a unique opportunity as it reviews the LCR in closer detail to acknowledge and promote a one-water framework for both drinking water and clean water utilities in their efforts as public health protectors and environmental stewards.

Opinions expressed here do not necessarily reflect those of the Sustainable Phosphorus Alliance.


National Association of Clean Water Agencies (NACWA) is the nation’s recognized leader in legislative, regulatory, legal and communications advocacy on the full spectrum of clean water issues. NACWA represents public wastewater and stormwater agencies of all sizes nationwide. Our vision is to advance sustainable and responsible policy initiatives that help to shape a strong and sustainable clean water future.