The Accotink Creek TMDL: Focusing on the Real Issue of Using TMDLs to Restore Degraded Urban Waters

When the Federal District Court in Alexandria ruled that stormwater flow cannot be regulated as a pollutant simply by developing a TMDL in which it is a surrogate, it did much more than stop an attempt at expanding EPA’s Clean Water Act (CWA) regulatory authority.   It put the spotlight on the illogical attempt to use TMDLs as the main tool to restore waters in highly urbanized areas.

The winning argument was simple.  The Federal CWA defines the term ‘pollutant’ that is regulated under Section 402 of the CWA.  Section 402 is the section where the National Pollutant Discharge Elimination System (NPDES) permitting program is located.   EPA argued that they had the ability to use surrogates to control pollutant discharge when a TMDL found that using a surrogate was a better approach to ensuring that water quality standards would be met.  In the case of Accotink, the surrogate chosen was stormwater flow.   The judge ruled that the CWA clearly defines what a pollutant is, and a surrogate that substitutes for a pollutant in a TMDL does not qualify as a pollutant.

Although the ruling stopped an ‘illegal’ approach to address urban stream impairments, it did not eliminate the seemingly myopic approach of using TMDLs as the keystone mechanism being considered by some to address these impairments.  There is complete agreement, as there was in the Accotink Creek case, that uncontrolled urbanization in a creek’s watershed can cause downstream channels to become unstable and flows to become flashy during rainfall events.  The disagreement comes as to how to address the issue.  Local governments and property owners see eroding channels and associated flooding causing property damage.  Water quality regulatory agencies see impaired waters based on the aquatic bug populations living in the stream.   Based on how one looks at the issue, different endpoints are likely and these endpoints can have widely different associated costs.

This brings us back to the problem of using TMDLs as the sole source to determine the endpoint of restoration efforts in urban streams.  Pollutant load reduction simply cannot guarantee water quality standards will be met if the reductions are met.  In the case of the Accotink Creek TMDL, discussion regarding reasonable assurance included language encouraging the use of a “comprehensive implementation approach that could include BMPs that directly restore/improve aquatic habitat (such as streambank restoration and reconnection of the floodplain to the stream), as well as BMPs that directly address the existing hydrologic alteration.”  It doesn’t matter if pollutant load discharges are eliminated altogether if aquatic habitat is not restored as well.  Habitat restoration is outside of the purview of any discharge permit.

So what is the solution to restoring impaired urban waters?  In many cases, identifying the cause of the impairment is simple – uncontrolled urbanization of the watershed.  However, that is where simplicity ends.  Altered stormwater discharge is just one of the impacts urbanization has on local streams.  Encroachment into historic floodplains, modified flow patterns, stream encapsulation and riparian zone destruction also combine with the altered stormwater discharge to impact the stream.  As such, there are usually no simple solutions.  On top of that, there are considerations outside of science and engineering such as private property rights and economics that must be taken into account.

In recent years, efforts such as riparian buffer protection and stormwater quantity design criteria have been put in place to minimize impacts of urbanization on local streams.  Continued effort must be taken to minimize impacts of future urbanization.  However, protecting from future impact does not remedy the past.  Urbanization in Virginia began over 400 hundred years ago.   Commitments by stakeholders must be made to address these past ‘sins’ as part of a comprehensive effort.   As redevelopment occurs, corrections must be required. Drainage and flood control projects should be designed and implemented to also address water quality issues.  Renewed efforts to protect and restore floodplains and riparian zones should be made.  Designs more sensitive to stream impacts should be used when replacing road crossings and rebuilding bridges.

There is a need for a comprehensive planning effort to identify what can be done in these urbanized streams, but that planning effort is not the same as a TMDL.  We can bring urbanized streams back to an endpoint; it may just not be an endpoint that satisfies everyone.  Development and implementation of watershed management plans for urbanized waters may require that we look at either different water quality standards or perform use attainability analyses.  In any case, only by working together while recognizing that complex problems require complex and flexible solutions will we restore water quality in our local urban streams.