A study that tests for parts of the coronavirus in sewage is giving public health workers advance notice of virus surges.

The Lawrence Journal-World reports that the City of Lawrence has been taking weekly sewage samples at both of its wastewater treatment plants to test for components of the virus as part of a study contracted through the University of Kansas School of Engineering.

The city has also been sharing that data with local and state health departments.

A Lawrence-Douglas County Public Health spokesman said that the presence of the virus in wastewater has served as an early predictor of surges in positive cases, providing about a week’s notice and giving the health department valuable lead time.

Research has shown that COVID-19 concentrations in wastewater rise about a week before a surge in new cases, and that both symptomatic and asymptomatic people with the virus shed components of it.