Rainfall Data Review for Stormwater Standards

Calvert County is reviewing updated rainfall data to determine whether current stormwater design standards should be revised.

This review is based on a recent local scientific study that suggests rainfall intensity in our area may be higher than what is reflected in the data currently used for stormwater system design.

No decisions have been made. We are seeking community input before determining next steps.

Why Is This Being Reviewed?

The University of Maryland Center for Environmental Science at the Chesapeake Biological Laboratory in Solomons conducted a study examining localized rainfall patterns in Calvert County.

The findings indicate that:

Rainfall intensity may be greater than previously recorded
Current stormwater design standards may not reflect updated local data
Because stormwater systems are designed using rainfall data, it is important to evaluate whether standards should be updated to reflect current science.

What Is Being Considered?

The County is evaluating whether to update the rainfall values used in stormwater calculations.

We are asking residents, property owners, developers and other stakeholders:
Do you support or oppose updating the rainfall data used for stormwater design in Calvert County?

What Would This Mean?

If the updated rainfall data is adopted, it would apply to:
Projects that do not yet have an approved Site Development Plan.

Potential impacts could include:

Projects currently in design may need to revisit stormwater calculations
Some development plans may require redesign to meet updated standards
Developers could experience changes to project timelines or costs

These potential impacts are part of what we are evaluating — and why your feedback matters.

Why Your Input Is Important

Stormwater standards affect:

Flood prevention
Infrastructure resilience
Environmental protection
Development planning
Project costs and timelines

Your perspective will help the County better understand potential benefits, concerns, and community priorities before making any decisions.

Questions?

For more information, please contact:
Calvert County Department of Public Works Engineering Division
📞 410-535-1600

"This is a science-based review process. Before making any decisions, we want to hear from our residents. Their feedback is critical to ensuring that any future changes are carefully considered and reflect the needs of our community."

John Cosgrove

Department of Public Works Director