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Stormwater Management Division

Mark Richmond, Chief

6751 Columbia Gateway Drive, Suite 514

Columbia, MD 21046



Downtown Ellicott City Flood Study

A detailed floodplain analysis using both one-dimensional and two-dimensional hydraulic modeling is available for viewing. The floodplain study considered several standard rainfall events as well as the rainfall event that resulted from the remnants of Tropical Storm Lee on September 7, 2011. The study also included a conceptual assessment of potential flood mitigation options.

  • Floodplain Study Report  
  • Inflow Hydrograph Comparison 
  • Rainfall Intensity Distribution Comparison 
  • Cumulative Rainfall Distribution Comparison 
  • Flooding Depth and Limits – Multiple Storm Events  
  • Conceptual Mitigation Options 

    The Howard County Flood Mitigation Plan 2013 Progress report is available for viewing here.


    The Tiber-Hudson and Plumtree Branch Stream Corridor Assessment

    a visual survey of the stream corridor to document conditions that potentially affect flood conditions, is now available. Also see the supplemental Case Study: Valley Mede-Ellicott City Tropical Storm Lee Flood Event 


    Howard County and the Master Gardeners:

    are providing free rainbarrels to residents who attend their training workshops. Here is a workshop schedule.  

    Learn more about the Watershed Protection and Restoration Fund

    MS4 NPDES Permit Annual Update Number 19

    In accordance with Howard County’s Municipal Separate Storm Sewer System (MS4) National Pollutant Discharge Elimination System (NPDES) Permit (Number MD0068322, 00-DP-3318), the County must prepare Annual Updates to report on the progress made during the preceding permit year. Progress is reported on compliance with pollutant source identification in stormwater runoff; water quality impacts; discharge characterization; management programs; watershed assessment and planning; watershed restoration; assessment of controls; program funding; Total Maximum Daily Loads (TMDLs); and special programmatic conditions. The County submitted the Annual Update for its 19th permit year to the Maryland Department of the Environment (MDE) on September 15, 2014. To view the County’s Annual Update Number 19 and the supporting databases, click here. 


    Mission Statement

    The mission of the Stormwater Management (SWM) division is to advance the quality of life for the citizens of Howard County through the improvement and management of the quality and quantity of water that originates in, falls onto, or passes through the county on its way to the Chesapeake Bay.

    The SWM division will accomplish this by:

    • communicating to the public the value of clean water and the ways they can personally improve water quality, 
    • monitoring and maintaining our public and private storm water facilities, 
    • planning, implementing, and maintaining a program for good water resource management, 
    • partnering with individuals, citizen volunteers, local environmental groups, businesses, schools, and other government agencies in an effort to promote beneficial water quality management,
    • responding to public inquiries and complaints in a courteous and timely manner, and 
    • evaluating and implementing technologies consistent with stormwater best management practices (BMP's). 


    Howard County Code


    Click on the topics below for more information