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:
Howard County Department of Public Works completed stormwater retrofit studies in the Plumtree Branch Watershed and Tiber Branch Watershed in the Ellicott City area. The studies included drainage assessments and improvement studies of:
Watersheds were divided into assessment areas and categorized for improved stormwater infrastructure and management and water quality opportunities:
Potential work in these areas depends upon further analysis, future funding, and each project’s prioritization relative to each other and to additional priorities throughout the County. Homeowners can also reduce runoff on their own properties by installing rain gardens and rain barrels, taking advantage of existing County cost-sharing, credit and reimbursement programs. See CleanWaterHoward.com for more information on water quality programs for residential properties.
The final studies are available for viewing. Comments and questions can be sent to
A comprehensive hydrologic and hydraulic analysis of the July 30, 2016 flooding event in the Valley Mede, Chatham and Nob Hill areas of the Plumtree Branch and Little Plumtree Branch watersheds of Ellicott City was completed in 2017. This analysis also modeled how certain water retention controls, stream channel enhancements and local drainage improvements may reduce the amount of flooding for various storm conditions. A formal presentation explaining the results of the drainage study took place at a public meeting on Wednesday November 15, 2017 starting at 7:00 PM in the George Howard Building’s Banneker Room at 3430 Court House Drive in Ellicott City. Presentation materials can be downloaded below.
The final hydrologic and hydraulic analysis report is available for viewing. Comments and questions can be sent to firstname.lastname@example.org.
An inspection of the storm drain system that serves as a conduit for Little Plumtree Branch drainage under MD Route 40 in the vicinity of St. John's Plaza in Ellicott City was completed in March 2018. The inspection report can be found here.
Howard County performs watershed restoration projects to help in meeting its National Pollutant Discharge Elimination System (NPDES) permit conditions and Total Maximum Daily Load (TMDL) goals and has selected the Font Hill Tributary Stream Restoration Project as part of its watershed restoration efforts. This tributary was identified in the Little Patuxent Watershed Study completed in February 2016. The project limits consist of the existing stream starting approximately 6,000 linear feet upstream from Centennial Lane to the downstream limit at Centennial Lane. The proposed project limits are completely contained within Howard County owned open space. This project is being completed by a design/build team comprised of Johnson, Mirmiran and Thompson, Inc. and Environmental Quality Resources, LLC. The document links below were presented at the initial project public meeting on November 30, 2017. The Font Hill Tributary Stream Restoration Project Construction Phase is anticipated to begin Fall 2018 and continue through to the beginning of Fall 2020.
Font Hill Presentation
Meeting Agenda and Stream Restoration FAQ
The Howard County Design Manual - Volume I has been revised and is available for viewing. Of particular note is the revision to the 24-hour rainfall rates for all design storms used in stormwater management computations and their effective date. Other minor revisions and clarifications have also been made.
Check out the many great options below! What shouldn’t you do? Do not dump leaves, grass clippings or other landscaping waste into a storm drain inlet or a stream. Why? This is bad for water quality and is considered an illicit discharge and a violation of County Code. Discarding landscape waste into a storm drain inlet can clog pipes and lead to flooding (even in your own yard). The decaying process of yard trim can also lead to depleted oxygen levels in our stream and water bodies.
What are my options for leaves/grass clippings?
For more details about these options, Visit www.howardcountymd.gov/yardtrim or call 410-313-6444.
Under Howard County’s National Pollutant Discharge Elimination System (NPDES) municipal separate storm sewer system (MS4) permit, the Maryland Department of the Environment (MDE) requires the County to annually submit all storm sewer system data and all stormwater best management practice (BMP) data, including delineated drainage areas, in geographic information system (GIS) format. To comply with this permit condition, the County has been requiring that digital design information related to BMPs and storm sewer systems be submitted with development plans as of July 1, 2017. These data will be incorporated into the County’s inventory for submittal to MDE.
Design information required to be submitted digitally includes:
Data can be submitted in a GIS geodatabase, as GIS shapefiles, or as AutoCAD dxf files with an associated completed Excel file. GIS format is preferred. Links to the GIS and Excel templates can be found here:
Maryland Department of the Environment (MDE) requires a permit for the discharge of any quantity of wastewater to ground and surface waters. Vehicle wash water is considered to be wastewater and therefore onsite vehicle washing requires a permit. Companies that perform outdoor vehicle washing have three options for managing the wastewater they generate:
1) Discharge wastewater to the sanitary sewer (please contact the Bureau of Utilities at 410-313-4943 for more information),
2) Contain, collect and transport wash water off-site for appropriate treatment and disposal, or
3) Obtain an MDE discharge permit to discharge to the ground and surface waters (Call the MDE Wastewater Permits Program at 410-537-3778).
Please go to the following links below for more information:
The Howard County Department of Public Works has undertaken a comprehensive watershed assessment within the Middle Patuxent River and the Little Patuxent River watersheds. The watershed assessment was performed to create an inventory of the natural resources as well as existing problems (erosion, trash, lack of wooded stream buffers, etc.) within these watersheds. Another result of the assessment is a list of potential projects that can be done to protect and restore these resources, address the problems, and ultimately improve water quality in our County streams and water bodies.
This assessment measured current environmental conditions and identified opportunities for restoration projects to be included in the capital budget. These projects will improve water quality in the County’s streams and rivers as well as the Chesapeake Bay. Potential projects investigated include stream restoration, adding water quality treatment to existing stormwater management ponds, constructing new stormwater management facilities, performing reforestation, and stabilizing existing storm drain pipe outfalls.
Due to the large overall study area, the field work was conducted in four distinct areas -- Northern Little Patuxent, Southern Little Patuxent, Northern Middle Patuxent, and Southern Middle Patuxent watersheds as depicted on the Little and Middle Patuxent Watershed Map. The County conducted a public meeting in each of the four study areas to report on the findings of field work results, to describe the next steps in the assessment study, to review possible restoration techniques, and to discuss the status of its countywide plan for meeting Chesapeake Bay Total Maximum Daily Load (TMDL) goals. Crews of two or three County employees or consultants conducted the field assessments, which entailed performing visual observations, taking photos, preparing sketches, and entering the data into handheld field tablets.
The results of the field assessments were used to score and rank the potential project sites, and concept plans were developed for the highest rated 148 sites. A report was generated for both the Little Patuxent and Middle Patuxent watersheds, which includes the study methodology, results, and the concept plans. Some concept plans are on private properties; however, these potential projects will only move forward with the permission of the property owners. These reports are available through the following links:
Little Patuxent Watershed Report
Middle Patuxent Watershed Report
If you have any specific questions or concerns or would like additional information regarding the watershed assessment, please contact the County by emailing Christine Lowe at email@example.com or calling 410-313-6444.
Past meeting presentations:
June 17, 2015 - Southerm Middle Patuxent Watershed
June 22, 2015 - Northern Little Patuxent Watershed
June 24, 2015 - Southern Little Patuxent Watershed
June 30, 2015 - Northern Middle Patuxent Watershed
December 2, 2015 - Northern Middle Patuxent Watershed
December 3, 2015 - Southern Little Patuxent Watershed
December 9, 2015 - Southern Middle Patuxent Watershed
December 10, 2015 - Northern Little Patuxent Watershed
Having completed the Little Patuxent and Middle Patuxent Watershed Assessment as noted above, the County has begun another watershed study for the remainder of the County. This study includes the Patapsco River and Mainstem of the Patuxent River watersheds. The study purpose and methodology are the same as the Little Patuxent and Middle Patuxent watershed assessment. Due to the large overall study area, the field work is being conducted in five distinct areas – South Branch Patapsco River, Lower North Branch Patapsco River, Brighton Dam/Triadelphia Reservoir, Rocky Gorge Reservoir, and Patuxent River Upper watersheds. Field assessments for this study were completed in April through May 2016.
(Click on the map for a larger image)
The County welcomes public participation in the development of the watershed study. The County conducted public meetings in Summer 2016 and January 2017 to report on the findings of field work results, to describe the next steps in the assessment study, to review possible restoration techniques, and to discuss its countywide plan for meeting local and Chesapeake Bay Total Maximum Daily Load (TMDL) goals.
The results of the field assessments were used to score and rank the potential project sites, and concept plans were developed for the highest rated 180 sites. A report was generated for both the Patuxent River and the Patapsco River watersheds, which includes the study methodology, results, and the concept plans. Some concept plans are on private properties; however, these potential projects will only move forward with the permission of the property owners. These reports are available through the following links:
Patuxent River Watershed Assessment Report
Patapsco River Watershed Assessment Report
A public review period for the watershed assessment reports is available until March 1, 2017. If you have any comments on the reports, any specific questions or concerns, or would like additional information regarding the watershed assessment, please contact the County by emailing Christine Lowe at firstname.lastname@example.org or by calling 410-313-6444.
Past Meeting Presentations:
June 21, 2016 – Rocky Gorge Reservoir and Upper Patuxent River Watersheds
June 23, 2016 - Lower North Branch Patapsco River Watershed
June 28, 2016 – South Branch Patapsco River and Brighton Dam/Triadelphia Reservoir Watersheds
January 23, 2017 – Brighton Dam/Triadelphia Reservoir, Rocky Gorge Reservoir and Upper Patuxent River Watersheds
January 26, 2017 – South Branch Patapsco River and Lower North Branch Patapsco River Watersheds
Small-Scale Programs – How You Can Help
South Branch Patapsco River
Concept Plan Sites
Patapsco River Lower North Branch – Upstream
Patapsco River Lower North Branch – Midstream
Patapsco River Lower North Branch – Downstream
Brighton Dam/Triadelphia Reservoir
Rocky Gorge Reservoir
Patuxent River Upper
Stormwater management facilities help remove pollutants from water and prevent flooding in our community. In order to do so, some of these facilities must temporarily or permanently retain water. If stormwater facilities are designed and maintained correctly, mosquito populations should not be a concern. Learn more on Stormwater Facilities and Mosquitoes webpage.
The Howard County Health Department has posted information regarding the Zika Virus. Please visit www.howardcountymd.gov/Departments/Health/Zika.
On December 18, 2014, Howard County received a new National Pollutant Discharge Elimination System (NPDES) Municipal Separate Storm Sewer System (MS4) Discharge Permit from the Maryland Department of the Environment (MDE). The County's MS4 permit includes requirements for watershed restoration activities, specifically preparation of a restoration plan within the first year of the permit term. To address this requirement, Howard County developed a Countywide Implementation Strategy (CIS) in 2015. A revised CIS was developed in 2017.
NOTE: The costs shown to implement the Financial Assurance Plan to meet the stated goals of the plan have been estimated. The cost estimates provided in the CIS will likely adjust as the County progresses with implementation of its program. Learn more about CIS.
A detailed floodplain analysis using both one-dimensional and two-dimensional hydraulic modeling is available for viewing. The floodplain study, which was completed in July 2013, 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.
The Howard County Flood Mitigation Plan 2013 Progress report is available for viewing here.
The Tiber-Hudson and Plumtree Branch Stream Corridor Assessment is a visual survey of the stream corridor to document conditions that potentially affect flood conditions. Also see the supplemental Case Study: Valley Mede-Ellicott City Tropical Storm Lee Flood Event
An above-water visual condition inspection of all the retaining walls located along the Hudson Branch and Tiber Branch in Old Ellicott City, MD was conducted in Spring of 2016. The purpose of this inspection was to assess the current condition of the walls and provide a tool for prioritizing the repair of the inspected walls.
Ellicott City Retaining Walls Inspection Report – Stream Walls
The University of Maryland Extension Master Gardeners and Howard County work together to offer residents free barrels to turn into rain barrels. Howard County residents are eligible to receive a free 55-gallon plastic barrel with cut-outs for fittings, to be used for a rain barrel (one free barrel per address, please). Residents must buy fittings and assemble the rain barrels. Rain barrels will only be offered to Howard County residents (ID required) and must be used in Howard County.
Recipients of the barrels must fill out pledge a form and take part in a short volunteer-led workshop at the Alpha Ridge Landfill.
Learn more here
In accordance with Howard County's National Pollutant Discharge Elimination System (NPDES) Municipal Separate Storm Sewer System (MS4) Permit (Number MD0068322, 11-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; management programs including stormwater management, erosion and sediment control and illicit discharge detection and elimination; restoration plans, watershed assessments, and Total Maximum Daily Loads (TMDLs); assessment of controls and monitoring; program funding; and special programmatic conditions. The County submitted the Annual Update for its 23rd permit year to the Maryland Department of the Environment (MDE) on December 17, 2018. To view the County’s Annual Update Number 23, click here.
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