Operating rules for an off-stream blending reservoir to control nitrate in a municipal water system

Jory S. Hecht, Ximing Cai, J. Wayland Eheart

Research output: Contribution to journalArticlepeer-review


Municipal water supply systems dependent on surface water sources that are susceptible to both low flows and contamination can use off-stream blending reservoirs (OSBR) both to increase their yield and avoid investments in expensive treatment technology. Three water quality operating rules (WQORs) are simulated from a retrospective planning perspective using the OSBR system that controls nitrate contamination for Pontiac, Illinois as an example case. These rules regulate pumped reservoir inflow based on (1) a maximum river concentration (Riv-CR), (2) a maximum reservoir concentration (Res-CR), and (3) a hybrid rule incorporating both maximum reservoir and river concentrations (Hyb-CR). The Hyb-CR rule typically registers the highest yield when nitrate is modeled as a conservative contaminant, while Res-CR tends to produce the highest yields when nitrate losses are considered. In general, reservoir concentration-based WQORs are effective for increasing the yield of OSBR systems that control the concentration of nonconservative contaminants, and often produce higher yields than a traditional Riv-CR, even with conservative contaminants. However, numerous circumstances are identified under which Riv-CR may outperform both Res-CR and Hyb-CR.

Original languageEnglish (US)
Article number04014015
JournalJournal of Water Resources Planning and Management
Issue number8
StatePublished - Aug 1 2014


  • Blending
  • Drinking water
  • Drought
  • Illinois
  • Nitrate
  • Off-stream reservoir
  • Simulation
  • Water quality
  • Water quality operating rules

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Geography, Planning and Development
  • Water Science and Technology
  • Management, Monitoring, Policy and Law


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