OWML Science

Microbial Source Tracking

Identifying and mitigating the source of fecal contamination to a particular waterbody is complicated by the fact that traditional measures of fecal bacteria concentrations are not host-specific. Microbial source tracking (MST) is a term used for the process of identifying the source of fecal contamination in the environment.  MST techniques are based on the concept that various warm-blooded animal intestinal systems have different selective pressures caused by differences such as diet and physiology that select for specific gut microbial populations.  MST attempts to utilize the unique microbial populations by host animal through identifying some unique genetic (DNA or RNA sequence) or phenotypic (observable characteristic or expression, such as antibiotic resistance) trait.  Although no standard methods exist for MST, host-associated genetic markers, also known as MST markers, have been developed to detect and quantify fecal contamination from sources including human, canine, ruminant, cattle, horse, swine, chicken, and waterfowl. Contact – Christopher Kephart (ckephart@usgs.gov)

Cyanobacterial harmful algal blooms (cyanoHABs)

The increasing prevalence of cyanobacterial harmful algal blooms (cyanoHABs) and the toxins they produce are a global water-quality issue that threatens human and wildlife health and necessitates additional monitoring of recreational and drinking water source waters. Multiple strategies to address

cyanoHABs are ongoing and include reducing nutrient sources, monitoring and predicting concentrations of toxins, minimizing exposures to humans and animals, and treating waters to reduce or eliminate cyanoHAB toxins once they occur. In Lake Erie and inland lakes in Ohio, elevated microcystin concentrations have caused water-resource managers to issue recreational water-quality advisories, and detections of microcystin in source waters have caused drinking-water plant managers to increase monitoring and adjust treatment methods (Ohio Environmental Protection Agency, 2015). Contact – Erin Stelzer (eastelzer@usgs.gov)

Early warning system to estimate toxic cyanobacteria bloom accumulation in US Lakes and Reservoirs

The USGS began a sampling and monitoring effort at Caesar Creek Lake and Clarence J. Brown Reservoir (Buck Creek Lake), Ohio as part of the Cyanobacteria Assessment Network (CyAN). The CyAN (https://www.epa.gov/water-research/cyanobacteria-assessment-network-cyan) is a multi-agency project between EPA, NASA, NOAA, and USGS to develop an early warning system using satellite data to detect cyanoHABs in freshwater systems. Microcystins and other cyanotoxins, however, are not pigments and cannot be directly detected by remote sensing.

In situ hydrologic, water-quality, biologic, and meteorologic data are collected during satellite overflights at inland lakes. Data will be incorporated into site-specific statistical models and used in the development of a nationwide tool to detect cyanoHABs, which will help anticipate and respond to cyanoHAB-related water emergencies. This study advances the understanding of toxic cyanoHABs in lakes and reservoirs, the processes that determine cyanoHAB formation, helps predict changes caused by cyanoHABs regarding the quantity and quality of water resources, and delivers timely hydrologic data, analyses, and water-resource decision-support tools.  Contact – Jessica Cicale (jcicale@usgs.gov)

Predictive models and NowCasting

Disease-causing (pathogenic) organisms and cyanobacterial harmful algal blooms (cyanoHABs) that produce toxins are widespread human-health and environmental threats to our recreational and drinking waters. Escherichia coli (E. coli) is one type of bacteria used to indicate when pathogens may be present. Microcystin is the most frequently detected toxin in freshwaters produced by certain species of cyanobacteria (the bacteria that cause cyanoHABs). However, traditional laboratory methods for detection of E. coli or microcystin often take too long to be useful for prompt public health protection. To address this, the U.S. Geological Survey (USGS) is collaborating with state and local partners to develop models that provide real-time estimates of E. coli and (or) microcystin levels at inland and Great Lakes beaches and drinking-water intakes.  Real-time estimates based on mathematical models are currently provided for 25 beaches and one recreational site through the Great Lakes NowCast (usgs.gov). This multi-state effort provides a single source for public notification and for partners to compile and manage data.