Real-Time Assessments of Water Quality—A Nowcast for Escherichia coli and Cyanobacterial Toxins

Fact Sheet 2019-3061
Prepared in cooperation with U.S. Environmental Protection Agency, Great Lakes Restoration Initiative
By: , and 



Threats to our recreational and drinking waters include disease-causing (pathogenic) organisms from fecal contamination and toxins produced by some species of cyanobacteria (cyanotoxins) that can cause acute and (or) chronic illnesses. Because traditional laboratory methods for detecting these threats take too long for prompt public health protection, tools for real-time assessments are needed to protect public health. To address this need, the U.S. Geological Survey is collaborating with State and local partners to develop models that provide real-time estimates of Escherichia coli (E. coli) (for pathogens) and (or) microcystin (for freshwater cyanotoxins) levels at inland and Great Lakes beaches and drinking-water intakes. Model results are then used to inform the public of water-quality conditions in near-real time through the Great Lakes NowCast ( Behind the scenes, the NowCast provides speed and efficiency for managers by automating data management and standardizing methods among agencies.

Suggested Citation

Francy, D.S., Brady, A.M., and Zimmerman, T.M., 2019, Real-time assessments of water quality—A nowcast for Escherichia coli and cyanobacterial toxins: U.S. Geological Survey Fact Sheet 2019–3061, 4 p.,

ISSN: 2327-6932 (online)

ISSN: 2327-6916 (print)

Table of Contents

  • Why Do We Need a Nowcast?
  • What Is a Nowcast and How Does It Work?
  • What Are the Data Requirements to Develop a Nowcast Model?
  • What Are the Steps for Nowcast Model Development, Testing, and Implementation?
  • What Are the Benefits of a Nowcast?
  • Operational Nowcast—The Great Lakes NowCast
  • What Is Next for the Great Lakes NowCast?
  • What Training Is Available to Develop a Nowcast?
  • How Well Does a Nowcast Perform as Compared to the Traditional Method for Determining Water-Quality Conditions?
  • References
Publication type Report
Publication Subtype USGS Numbered Series
Title Real-time assessments of water quality—A nowcast for Escherichia coli and cyanobacterial toxins
Series title Fact Sheet
Series number 2019-3061
DOI 10.3133/fs20193061
Year Published 2019
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Pennsylvania Water Science Center, Ohio-Kentucky-Indiana Water Science Center
Description 4 p.
Online Only (Y/N) N
Google Analytic Metrics Metrics page
Additional publication details