Impact of Septic System Disposal on Surface Water Quality

EPA Grant Number: MA916978
Title: Impact of Septic System Disposal on Surface Water Quality
Investigators: Seiber, Kathy L.
Institution: California State University East Bay
EPA Project Officer: Lee, Sonja
Project Period: September 1, 2008 through August 31, 2010
RFA: GRO Fellowships for Graduate Environmental Study (2008) RFA Text |  Recipients Lists
Research Category: Academic Fellowships


There are approximately 1.2 million onsite wastewater treatment systems in California. However without regular maintenance septic systems may fail and leak untreated or improperly treated sewage into the environment, contaminating adjacent groundwater and surface waters. This study will investigate the connection between septic systems and the impact on surface water quality.

The overarching goal of this study is to improve public health by understanding the factors that lead to microbial contamination associated with private sewage disposal (cesspools and septic systems) adjacent to surface waters in Northern California and work with local government and residents to prevent pollution of these waters. The research objectives are to: (I) determine the connectivity between domestic sewage disposal systems and adjacent surface waters; (II) evaluate the relationship between the presence of fecal indicator organisms and the presence of pathogens in surface waters impacted by septic sewage contamination; (III) determine the environmental factors affecting distribution and persistence of fecal indicator organisms and pathogens in surface waters impacted by septic sewage contamination


A pilot study will be performed to identify locations of surface waters in Northern California that are likely impacted by septic tank seepage and to develop a targeted event-based sampling strategy. Surface waters impacted by septic seepage will be monitored for microbial water quality and environmental parameters such as temperature, salinity and turbidity. Water will be tested for a suite of fecal indicator organisms, including E. coli, Enterococci, Clostridium perfringens and bacteriophage, as well as for waterborne pathogens, such as enteric viruses. Intensive sampling will be conducted to assess relationships between water quality and environmental factors likely to affect water quality and to assess the presence of pathogens and their relationship to indicator organisms.

Expected Results:

This study will increase the understanding of the ecology and persistence of fecal pollution indicators and pathogens in surface waters that are influenced by anthropogenic activities. This project will generate valuable data sets of fecal pollution indicator and waterborne pathogen occurrence in surface waters affected by septic tank wastewater disposal, and the relationship these have to environmental conditions. Data generated will be shared with local regulatory agencies in order to determine best waste and surface water management practices for the area. Improved wastewater management and increased public awareness will protect surface water quality and reduce the risk to human health for users of these waters.

Supplemental Keywords:

Septic system, surface water, water quality, fecal indicator bacteria, wastewater, pathogen, survival,

Progress and Final Reports:

  • 2009
  • Final