Central Valley Wastewater Data
Four communities in Yolo County – Davis, Esparto, Winters, and Woodland – take part in Healthy Central Valley Together and results are updated as data becomes available, one to two times per week.
The chart for each city shows trends in three genes of SARS-CoV-2, the virus that causes COVID-19, that are detected in wastewater.
In this example showing results from one month of monitoring, the incidence of COVID-19 has been climbing steadily, with incidence of the targeted variant rising as well.
(Please be patient to allow the data to appear)
What We Measure
The N and S genes show the total incidence of COVID-19 because these two genes generally are present in any form of the virus. The third gene shown tracks a specific variant of the virus that public health officials are watching closely. We currently measure a mutation (called LPPA24S) found in the BA.2, BA.4 and BA.5 variants.
We also measure a generally harmless virus called pepper mild mottle virus or PMMoV, which is one of the most abundant viruses in human waste. We use PMMoV as an indicator of the “fecal strength” of each sample, which can change for different population sizes and factors like rain or water usage. Dividing (or normalizing) the SARS-CoV-2 concentration by PMMoV lets us compare results over time and from place to place.
Interpreting the Charts
The lines show if the overall presence of the virus and the variant being tracked are rising, falling or staying about the same. The dotted lines allow you to compare the most recent levels of virus with the level two weeks earlier (labeled 2w ago) and half the level two weeks earlier (labeled half 2w ago). Results are updated as new data become available, usually one-to-two times each week.