Ground and Surface Water Quality Issues Related to Ethanol Production and Use

New federal ethanol use mandates will lead to a rapid doubling of US corn ethanol production and use to almost 12 billion gallons in 2010 from the current (2007) use of 6.5 billion gallons. Non-point water quality impacts from >25 million acres of corn needed as feedstock have not yet been included in full life cycle evaluations of ethanol use, and potential point source impacts from ethanol releases during distribution and storage will also require assessment. About 60% of US gasoline was blended with ethanol in 2007, usually at 10% by volume. However initiatives and testing programs are ongoing which are assessing the emissions and material compatibility issues of the potential use of ethanol blends of 11-20% or higher, and there is very limited use of E85 (~81% ethanol). It is important to identify all known release scenarios (e.g., small chronic releases, sudden large releases, etc.) and receptors (e.g., surface and ground water, utilities) for these different fuel formulations, and assess the adequacy of current release investigation and management procedures. Existing conceptual models for spill response and corrective action require review to fully account for all important direct and indirect effects. While ethanol is readily biodegradable in water, transformation rates and overall water quality impacts will be site specific. Additionally, non-point source water quality impacts and sustainability issues related to this biofuels transition require EPA evaluation. The ecological impacts (pesticides, fertilizer, soil erosion, etc.) from this scale of feedstock production for corn or other ethanol feedstocks are yet to be assessed or compared to the environmental impacts of equivalent petroleum energy production. Metrics will need to be developed that will allow comparisons of relative environmental impacts.