Stormwater Beyond NPDES with Caleb Rennaker from IDEM
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Key Topics
Caleb Rennaker’s role as Watershed Planning and Restoration Section Chief with IDEM, and his introduction as the podcast’s first guest from a state regulatory agency.
Why public communication matters for non-point source pollution, since roughly 70 to 80 percent of impacted water bodies stem from non-point sources rather than a single regulated pipe.
The challenge of translating acronym heavy regulatory language into messaging the public can understand and act on.
How urbanization creates both challenges and opportunities, since converting agricultural or undeveloped land into an MS4 regulated area brings new water quality controls into play.
MS4 programs as a practical framework connecting local planning, public education, infrastructure partnerships, and measurable water quality outcomes, beyond simple permit compliance.
The Clean Water Act Section 319 grant program, which funds non-point source management through watershed planning and implementation, typically covering most project costs through a cost share model.
How Indiana builds watershed management plans that meet EPA’s nine key elements before becoming eligible for implementation funding.
EPA’s Nonpoint Source Success Stories database, where Indiana submitted thirteen stories in 2025, the most of any state that year, documenting improvements tracked over 10 to 20 year periods.
Total Maximum Daily Load basics, including how pollutant load allocations are calculated for a watershed and how MS4 stormwater contributions are estimated using land based area rather than direct outfall measurement.
The TMDL program’s consent decree era, when states focused on hitting numerical quotas, and how Indiana now prioritizes watersheds where a TMDL can lead directly into implementation work.
The importance of data sharing between regulated entities, watershed groups, and IDEM, including Indiana’s growing use of externally submitted data that meets state QA and QC standards.
Quote
“We’re not gonna solve the challenges that we have today by just attacking the problems in our little micro programs that are often understaffed and under-resourced. We really need the buy-in from the public.” ~Caleb Rennaker
In this episode, host Ty Garmon sits down with Caleb Rennaker, Watershed Planning and Restoration Section Chief at IDEM, for the podcast’s first conversation with a state regulator. Caleb explains why public education on non-point source pollution is difficult, walks through how the Clean Water Act Section 319 program funds watershed planning and implementation, and unpacks Total Maximum Daily Loads and their overlap with MS4 permits. The conversation covers Indiana’s push to document success stories, the value of sharing environmental data, and why partnerships beat going it alone.
The views expressed are that of the individual and do not represent the opinions of any companies past, present or future.
Connect with Caleb Rennaker:
LinkedIn: https://www.linkedin.com/in/caleb-rennaker-2a321191
IDEM Nonpoint Source Program: https://www.in.gov/idem/nps/
Email: crennake@idem.in.gov
Connect with Ty Garmon, LEED AP:
Connect with Ty on LinkedIn: https://www.linkedin.com/in/tygarmon/
Sign up to be a guest: https://forms.gle/whijSz9Tio3iZda57
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