Monthly Data

Twice monthly, the Storm Drain Detectives monitor the Mokelumne River using five different water quality tests at nine sites along the River and Lake. The measurements are recorded and posted by month on this page. Along, with these measurements, comments are also included. Each measured value is assigned a grade of A, B, C, D, or F. These grades are based on the San Joaquin River Basin Plan ambient water quality. 

These grades help to indicate the condition of the river or storm drains at the individual site locations. Try comparing a site’s grade from one month to the next, or compare one site to another to see if that part of the river is declining or improving. Definitions for terms that are used on the monthly charts can easily be defined in the Glossary link. Explanations of the five water quality tests can also be found in the What Do We Do? page. The river sites are listed by numbers on the monthly charts that correspond to their location and description in the Lodi Storm System Map page.

Compare Results

Have fun watching developments in the river’s checkup from month to month. Is the site nearest your house receiving good or bad grades? Using our measurements and the other resources available on the Storm Drain Detective’s website, hopefully you can learn more about the impact you make on storm drains and the river.

View monthly testing results for City of Lodi

Secchi Disk Dip-In

On, Monday, July 13, 2020, just after noon, Storm Drain Detective leaders dropped a Secchi disc into Lodi Lake and the Mokelumne River to measure water clarity, adding their findings to the 2020 Annual Secchi Dip-In, a volunteer waterbody monitoring event. This is the twentieth year Lodi has participated. Click the following link for more information and the results of this testing: Press Release- 2020 Secchi Disk Dip-In