Potential legislation may require Wastewater Treatment Plants to limit phosphorous concentration levels


Wastewater treatment plant

Recent action taken by the Ohio Environmental Protection Agency (Ohio EPA) could lead to more restrictive legislation governing phosphorous levels from Wastewater Treatment Plants (WWTPs) around Ohio.

In late 2017, the Ohio EPA submitted a Domestic Action Plan (DAP) to the U.S. Environmental Protection Agency (U.S. EPA) for its review. The primary goal of the DAP is to reduce the amount of total and dissolved reactive phosphorous entering Lake Erie each year, culminating in a 40 percent total spring load reduction in phosphorous levels by 2025. Heightened phosphorous levels have contributed to an increasing number of algal blooms since the mid-1990s, leading to detrimental effects on the Lake Erie watershed and surrounding areas.

The majority of phosphorous runoff comes from non-point sources (shown in the chart below). Approximately 9 percent of the phosphorous entering the Maumee River watershed originates from various treatment or industrial plants with a National Pollution Discharge  Elimination System (NPDES) permit. Phosphorous from NPDES sources is further broken up, with major WWTPs contributing a sizable portion of the total phosphorous levels from NPDES sources.

One of the ways in which the Ohio EPA plans to lower phosphorous levels entering the Lake Erie watershed is to strictly regulate WWTPs discharging phosphorous throughout Ohio. Currently, Ohio does not have any existing laws regulating WWTP phosphorous levels. However, the Ohio EPA has stated in its DAP that it “will evaluate possible legislation that will limit all treatment works discharging wastewater containing phosphorous to achieve at least a monthly average effluent concentration of 1 mg/L phosphorous unless alternative limits or conditions are deemed appropriate by the Director.”

If the U.S. EPA approves the Ohio EPA’s action plan, and the Ohio EPA decides to pursue legislation further limiting phosphorous discharges, WWTPs throughout the state may need to implement additional phosphorous treatment measures to meet the proposed stricter discharge guidelines. Such measures would likely result in significant costs to the WWTPs affected, and WWTPs would be wise to begin researching options sooner rather than later.

It is important to note that since the Ohio EPA does not currently have the statutory authority to require such phosphorous limits, the Ohio legislature must pass legislation to statutorily mandate the proposed phosphorous limits.  Any subsequent change in Ohio law will take time to achieve, and any WWTPs or other entities that may be affected by the DAP will have additional warnings of potential changes in the law before any stricter guidelines are implemented.

The Ohio EPA expects the U.S. EPA to respond to the DAP within the next few months. (A response was originally expected in February 2018, but that now appears to be unlikely. It is important to note that the U.S. EPA will not be “approving” the DAP per se but will just be offering comments. Each state has a DAP, and the U.S. EPA is preparing a nationwide DAP for the entire country. The U.S. EPA will be interested in how Ohio shows progress in meeting its 40 percent phosphorus reduction goal, either through actual monitoring or modeling. However, nothing is currently set in stone; the DAP is admittedly a work in process and will be tweaked along the way. In fact, the process has been described as “building the airplane while it is going down the runway.”

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