A Screening Assessment of the Potential Impacts of Climate Change on the Costs of Implementing Water Quality-Based Effluent Limits at Publicly-Owned Treatment Works (Potws) in the Great Lakes Region (External Review Draft)
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Abstract
EPA has released this draft document solely for the purpose of pre-dissemination peer review under applicable information quality guidelines. This document has not been formally disseminated by EPA. It does not represent and should not be construed to represent any Agency policy or determination. EPA will consider any public comments submitted in accordance with this notice when revising the document.
This report describes the potential scope and magnitude of climate change impacts on the cost of meeting water quality based effluent limits at publicly owned treatment works (POTWs) discharging to rivers and streams in the Great Lakes Region (GLR). The report is a screening level analysis focusing on costs of meeting water quality based effluent limits for a single pollutant, biochemical oxygen demand, at all POTWs in the region discharging to currently impaired stream reaches. POTWs discharge billions of gallons of effluent daily to receiving water bodies throughout the U.S. One of the principal pollutants associated with POTW effluent is organic matter. Naturally occurring microbial populations in receiving waters consume dissolved oxygen (DO) as they decompose organic matter. Low DO is a significant source of water quality impairment.
Climate change in many parts of the country is expected to increase the proportion of rainfall occurring in high intensity events, resulting in increased stormwater runoff. At the same time, a shift towards more intense storms is expected to decrease infiltration and groundwater recharge, resulting in reduced low flow periods between events. Increased air temperatures and evapotranspiration could also result in reduced streamflow between rainfall events. Reduced low flow events in receiving waters could result in increased water quality impairment below POTWs due to reduced dilution of effluent.
This report describes the potential scope and magnitude of climate change impacts on the cost of meeting water quality based effluent limits at publicly owned treatment works (POTWs) discharging to rivers and streams in the Great Lakes Region (GLR). The report is a screening level analysis focusing on costs of meeting water quality based effluent limits for a single pollutant, biochemical oxygen demand, at all POTWs in the region discharging to currently impaired stream reaches. POTWs discharge billions of gallons of effluent daily to receiving water bodies throughout the U.S. One of the principal pollutants associated with POTW effluent is organic matter. Naturally occurring microbial populations in receiving waters consume dissolved oxygen (DO) as they decompose organic matter. Low DO is a significant source of water quality impairment.
Climate change in many parts of the country is expected to increase the proportion of rainfall occurring in high intensity events, resulting in increased stormwater runoff. At the same time, a shift towards more intense storms is expected to decrease infiltration and groundwater recharge, resulting in reduced low flow periods between events. Increased air temperatures and evapotranspiration could also result in reduced streamflow between rainfall events. Reduced low flow events in receiving waters could result in increased water quality impairment below POTWs due to reduced dilution of effluent.
Impact/Purpose
This report describes the potential scope and magnitude of climate change impacts on the cost of meeting water quality based effluent limits at publicly owned treatment works (POTWs) discharging to rivers and streams in the Great Lakes Region (GLR).
Status
Following the public comment period, the report will undergo an external peer review. The report will then be revised to address comments and posted on the NCEA web page. EPA will consider any public comments submitted in accordance with this notice when revising the document.
Citation
U.S. EPA. A Screening Assessment of the Potential Impacts of Climate Change on the Costs of Implementing Water Quality-Based Effluent Limits at Publicly-Owned Treatment Works (Potws) in the Great Lakes Region (External Review Draft). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-07/034A.
History/Chronology
| Date | Description |
|---|---|
| Sep 2006 | External review draft completed. |
Additional Information
Comments on this report may be submitted and reviewed using the e-Government Regulations.gov Web site. From the site, select Environmental Protection Agency and the keyword EPA-HQ-ORD-2007-0240 (for the docket ID) to comment on this report.