Muddy Waters: Virginia's Proposed Numeric Turbidity Criteria and Potential Compliance Challenges

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On April 12, 2021, the Virginia Department of Environmental Quality (DEQ) issued a Notice of Intended Regulatory Action (NOIRA) to establish first-time numeric turbidity criteria for Commonwealth surface waters in response to a directive by the State Water Control Board.  The establishment and potential enforcement of numeric turbidity criteria would impact a wide range of potential regulated industries, including construction, mining, infrastructure projects, and municipal stormwater discharges.

Currently, Virginia regulates turbidity through general narrative criteria.  Specifically, Virginia's Administrative Code lists turbidity as a substance requiring control when turbidity contravenes established standards, interferes directly or indirectly with designated uses of such water, or which are harmful to human, animal, plant, or aquatic life. (9VAC25-260-20).  As opposed to numeric criteria, which establish quantitative pollution concentration limits, narrative criteria use qualitative considerations to help identify unacceptable conditions of that waterbody.  Narrative criteria often supplement numeric criteria or are used when the regulated pollutant is difficult to measure.

The NOIRA's scope was far-reaching and sought public comment on a broad range of considerations on how to develop and implement numeric criteria.  This includes comments on ways to measure costs and benefits of numeric criteria, alternatives to the use of numeric criteria, and the potential impacts on the regulated community, including impacts on small businesses.

The breadth of the NOIRA was likely due to the difficulty in regulating turbidity.  Turbidity itself is not a pollutant, but a measure of a waterbody's clarity.  In other words, turbidity is a measurement of how much light is scattered by material in the water.  Turbidity makes water opaque, which in turn can affect the waterbody's ecological productivity, and can present health concerns.  The difficulty is that turbidity has numerous natural causes.  This can include the concentrated presence of organisms such as phytoplankton, natural erosion, storms, and discoloration of the water from natural minerals or decomposing vegetation.  In addition, turbidity may fluctuate significantly depending on seasonal factors, temperature variations, and storm activity.  There are certainly human causes of turbidity, such as construction site or agricultural runoff, dredging projects, and local boat traffic, but it may be difficult to identify the cause or causes of turbidity, whether natural or man-made, at any one time. Nor are we aware of a comprehensive repository of historical turbidity for the Commonwealth's waterbodies, so there may not be good baselines against which to measure an activity's impact on the waterbody.

It is also unclear what additional value a numeric turbidity standard would have over existing numeric standards for conventional pollutants.  The most likely contributor to turbidity from land-based human activity is sedimentation.  This, however, is already regulated through a network of general and activity-specific permits that regulate the suite of conventional pollutants, such as Total Suspended Solids (TSS), and through enforcement of erosion and sediment control (ESC) requirements.  The NOIRA does not specify that current permit limits are insufficient or otherwise what new concerns are driving this undertaking.

Media reports, however, have attributed this regulatory effort to frustrations with sedimentation of local waters allegedly caused by the Mountain Valley Pipeline.   If true, this raises additional concerns that one local project is driving regulatory activity that will impact a wide array of industries throughout the Commonwealth that have no commonality.  In other words, as noted by some public comments to the NOIRA, this turns the regulatory process on its head by seeking a state-wide solution to an issue that has not been identified as a state-wide problem.  The costs associated with a new regulatory regime, however, could be substantial considering the number and variety of businesses and municipalities that could be affected by new regulations.  Further, the difficulty in identifying a source of turbidity could result in downstream activities bearing a disproportionate burden of compliance costs.

The NOIRA was the first step in DEQ's assessment of numeric turbidity standards.  After consideration of public comments, we expect DEQ will convene an advisory committee comprised of representatives from interested parties, such as environmental and trade groups, state agencies, and localities.

Permitted activities in Virginia should follow this rulemaking as it has the potential to significantly alter their compliance requirements if numeric standards are incorporated into general or activity-specific permits.  This could include new requirements for turbidity field testing, more stringent ESC plans, and even the potential for temporary project shutdowns during periods of high turbidity.

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