The city of Cleveland Water Department (CWD) provides drinking water to approximately 1.5 million people in 72 communities in Northeast Ohio. The water system’s source is the Lake Erie Central Basin. A system of four water intakes, covering approximately 27 miles of shoreline in the greater Cleveland area, draw water into the CWD’s water treatment plants, which can be exposed to hypoxic (i.e. low oxygen) waters from Lake Erie, compromising water quality in the system. When upwelling events cause hypolimnetic waters to reach CWD intakes, pre-treatment operations are disrupted and corrosion control strategies are impacted by decreases in water temperature and pH. As a result, reduced and dissolved forms of iron and manganese from the hypolimnion enter the distribution system resulting in numerous customer water quality complaints about discolored water (Ruberg, Guasp (CWD Operations Manager), et al ).
Real-time information about the environmental conditions leading to the development of hypoxia can give drinking water managers time to prepare alternate processing methods in the event that low temperature and low pH hypolimnetic waters with increased levels of iron and manganese are transported to water intakes. Beginning in 2007, GLERL initiated a public-private partnership with the CWD to provide Lake Erie central basin environmental information through a hypoxia observation buoy system developed under GLERL’s Real-time Coastal Observation Network (ReCON). The hypoxia observation buoy system is a combination of instrumentation that is capable of providing real-time dissolved oxygen levels on the lake bottom, the vertical temperature gradient of the water column, and surface meteorological conditions. Information from the system is served to central basin drinking water processing managers from a GLERL website , providing hourly updates of decreasing dissolved oxygen, lake temperature stratification, and potential upwelling status using buoy surface meteorological conditions and the GLERL lake circulation model.
In 2014, NOAA/GLERL partnered with the CWD and the non-profit Great Lakes Observing System (GLOS) Regional Association to transition the real-time hypoxia observation buoy component of the Hypoxia Warning System into operations. A request for proposals was written based on the hypoxia observation system specifications provided by GLERL; the specifications for the system were obtained from years of GLERL central Lake Erie hypoxia observations research and development. GLOS secured funding from the CWD to purchase data from buoys providing physical, atmospheric, and water quality conditions needed to adequately characterize the conditions of the hypoxic zone in Lake Erie. Industry partner Limnotech was selected under a competitive award for buoy deployment, maintenance, and retrieval. The transition of this project into operations is the culmination of GLERL technology research and development under ReCON that goes back to 2004. This project was initially funded by GLERL through base funding and was funded under the Great Lakes Restoration Initiative from 2012 to 2014.
The customers of the Hypoxia Warning System attest to its value. Scott Moegling, Water Quality Manager with CWD stated, “Our first priority is the health of our customers. We receive valuable and complex information in real time with these buoys. That data is an important addition to our treatment tool kit.”
1.RUBERG, S.A., E. Guasp, N. HAWLEY, R.W. MUZZI, S.B. BRANDT, H.A. VANDERPLOEG, J.C. LANE, T.C. MILLER, and S.A. CONSTANT. Societal benefits of the real-time coastal observation network (ReCON): Implications for municipal drinking water quality. Marine Technology Society Journal 42(3):103-109 (2008).
GLERL hypoxia observations website 2007-2014: https://www.glerl.noaa.gov//res/recon/station-clv.html. Hypoxia Warning System, 2014-present: https://www.glerl.noaa.gov/res/HABs_and_Hypoxia/hypoxiaWarningSystem.html