Unit 6

Advanced Master Gardener – Water Program Manager

Unit 6: Stormwater and Watersheds


Many land practices impact surfacewater.  Water that runs off the land – “runoff” – during storms is called stormwater.  The amount, speed of the runoff, and quality of the water that runs off impacts surfacewater, and are all of these factors are impacted by various land practices.  Advanced Master Gardeners as Water Program Managers therefore have many opportunities to impact storm water quantity and quality themselves. More importantly, they are in a position to help their neighbors and their communities make correct decisions with respect to land care practices that could impact stormwater quantity and quality in their watershed.

Several concepts are important to understanding the impact of land care practices on stormwater and surfacewater quantity and quality.  Watersheds allow for the development of specific strategies unique to the inputs and land uses within a drainage basin.  The specific strategies are selected for use in fulfilling requirements of the Clean Water Act, the Virginia Stormwater Management Act and the Virginia Stormwater Management Program Permit Regulations, Total Maximum Daily Loads and Municipal Separate Storm Sewer Systems permits.


Watershed / tributary strategies and Total Maximum Daily Loads (TMDLs)


When waters of the United States do not meet the Clean Water Act goals of “fishable” and “swimmable,” jurisdictions develop EPA-approved lists of waterways impaired by pollutants that prevent them from meeting water quality standards.  A maximum amount of a pollutant is established.  The amount is what can enter the waterway and the waterway still meet water quality standards.

The watershed then becomes the land area that potentially contributes to pollutants in the impaired waterway.  The Chesapeake Bay Agreement of 2000 proposed necessary reductions in nutrients and sediments.  In response, watershed-wide plans were developed for the five major rivers and their tributaries within the drainage basin.  The “tributary strategies” were replaced after the establishment of TMDLs when goals for nutrient and sediment reduction had not been met by the agreement date of 2010.

Virginia Department of Environmental Quality. No date. “VEGIS” (Virginia Environmental Geographic Information Systems). Accessed September 3, 2014. http://www.deq.virginia.gov/ConnectWithDEQ/VEGIS.aspx.

U.S. Environmental Protection Agency. 2013. “Chesapeake Bay Total Maximum Daily Load (TMDL): Driving Actions to Clean Local Waters and the Chesapeake Bay.” Public domain. Accessed September 8, 2016. https://www.epa.gov/chesapeake-bay-tmdl/chesapeake-bay-tmdl-fact-sheet.

U.S. Environmental Protection Agency. No date. “Chesapeake Bay TMDL.” Accessed December 29, 2014. http://www.epa.gov/chesapeakebaytmdl/.

U.S. Environmental Protection Agency. 2013. “Total Maximum Daily Loads (TMDLs) at Work: Virginia – Restoring the legendary Lynnhaven Oysters.” Accessed September 8, 2016. https://nepis.epa.gov/Exe/ZyPDF.cgi/P1007N7Y.PDF?Dockey=P1007N7Y.PDF.

Center for TMDL and Watershed Studies. No date. “TMDL Studies.” Biological Systems Engineering, Virginia Tech. Accessed December 29, 2014. http://www.tmdl.bse.vt.edu/outreach/C68/.


Virginia Stormwater Management Program


The Virginia Stormwater Management Program (VSMP) is responsible for permitting and enforcement activities required by the Clean Water Act and the State Water Control Law.  Permits issued by the VSMP are the equivalent to a NPDES permit.

Code of Virginia. § 62.1-44.2 et seq. State Water Control Law. Accessed September 8, 2016. http://law.lis.virginia.gov/vacode/62.1-44.2/.

Virginia Department of Conservation and Recreation. 1999. Virginia Stormwater Management Handbook, Vol 1. Richmond VA: Department of Conservation and Recreation. Accessed November 11, 2014. http://www.deq.virginia.gov/Portals/0/DEQ/Water/Publications/HndbkVolumeI.pdf.

Virginia Department of Conservation and Recreation. 1999. Virginia Stormwater Management Handbook, Vol II. Richmond VA: Department of Conservation and Recreation. Accessed November 11, 2014. http://www.deq.virginia.gov/Portals/0/DEQ/Water/StormwaterManagement/SWMHandbookVolume%20II.pdf.


Municipal Separate Storm Sewer System Permits (MS4s)


Polluted stormwater runoff is often discharged without treatment into surfacewaters.  To regulate this and help prevent harmful pollutants, the U.S. Environmental Protection Agency (EPA) began requiring a National Pollutant Discharge Elimination System (NPDES) permit for operators (local jurisdictions, communities or businesses).  In 1990 Phase I was invoked which required medium and large cities (generally those with populations greater than 100,000) and certain counties to obtain NPDES permits for stormwater.  In 1999, Phase II required urbanized areas and smaller municipalities to obtain NPDES permits.  In general, Phase I permits are required to file and obtain individual NPDES permits, while the Phase II participants are covered by general permits.

Stormwater runoff does not routinely enter the sanitary sewer system.  The stormwater that is collected at curbside, etc., is generally piped separately than sewerage, and generally flows directly to stormwater features such as stormwater ponds or directly to a surfacewater stream or river.  The system to handle stormwater is known as a Municipal Separate Storm Sewer System (MS4).  Each MS4 permit requires the development and implementation of a stormwater management program (SWMP) to reduce the contamination of stormwater runoff and prohibit illegal discharges into stormwater systems.  The EPA provides information pertaining to MS4s and permitting, along with fact sheets and a national menu of Best Management Practices (BMPs).

Virginia Department of Environmental Quality. No date. “Virginia Pollutant Discharge Elimination System Permit Program.” Accessed December 29, 2014. http://www.deq.virginia.gov/Programs/Water/PermittingCompliance/PollutionDischargeElimination.aspx.

U.S. Environmental Protection Agency. 2014. “Stormwater Discharges from Municipal Sources.” Accessed September 8, 2016. https://www.epa.gov/npdes/stormwater-discharges-municipal-sources#overview.

Virginia Department of Environmental Quality. No date. “Municipal Separate Storm Sewer Systems (MS4) Permits.” Accessed December 28, 2014. http://www.deq.virginia.gov/Programs/Water/StormwaterManagement/VSMPPermits/MS4Permits.aspx.

U.S. Environmental Protection Agency. 2014. “National Menu of Stormwater Best Management Practices.” Accessed September 8, 2016. https://www.epa.gov/npdes/national-menu-best-management-practices-bmps-stormwater#edu.

Watershed Utility Fees


As development produces more impervious surface, the amount of stormwater increasingly challenges the ability of municipal stormwater systems to meet water quality requirements.  In contrast to water and wastewater infrastructure which is traditionally funded through municipal bonds and U.S. Environmental Protection Agency (EPA) State Revolving Loan funds, stormwater systems are typically funded through a limited share of local general funds (as a part of a proffer during new development) or through stormwater utilities.  However, building new stormwater infrastructure, retrofitting aging stormwater infrastructure, meeting new stormwater quality requirements, and increasing expenses for engineering and construction can challenge the ability of community general funds to provide adequate funding.  As a result, a more comprehensive approach that uses new financing mechanisms may be required to fund stormwater infrastructure.

One approach takes the form of a Stormwater Utility Fee.  Sometimes disparagingly referred to as “rain tax,” they are not generally taxes but fees based on usage of the infrastructure.  In Virginia this usage is often calculated based on the amount of impervious surfaces such as parking areas and structures.  Sometimes the fee can be offset by employing onsite stormwater techniques such as Low Impact Development, or traditional stormwater structures such as retention ponds.  The Code of Virginia allows any locality that establishes a watershed stormwater management program to establish a utility fee or enact a system of service charges.  The charges must be a dedicated special revenue, and may not exceed the actual costs of the utility.

Code of Virginia. § 15.2 – 2114. Regulation of stormwater. Accessed September 8, 2016. http://law.lis.virginia.gov/vacode/15.2-2114/.

Advanced Master Gardeners opportunities


There are many opportunities for MGs to contribute to community needs regarding MS4 permits.  The “six minimum control measures” enumerated by the EPA are elements that should result in a significant reduction in pollutants discharged to receiving waters.  These six minimum control measures are required to be a part of a program for all MS4s.  The minimum measures include:

  • Public Education/Outreach
  • Participation/Involvement
  • Illicit Discharge Detection and Elimination (IDDE)
  • Construction Site Runoff Control
  • Post-Construction Runoff Control
  • Pollution Prevention/Good Housekeeping

Of these, education and outreach are primary MG program activities, and are ways for local governments to achieve goals with minimal expense of revenues from fees or service charges.  Many communities already employ MGs to help with public outreach and education.  The Advanced Master Gardener – Water Program Manager should be familiar with Virginia’s approach to MS4 permits in order to impact local needs.  Examples are provided to stimulate ideas of possible programs for the Water Manager to consider.

U.S. Environmental Protection Agency. 2014. “Public Education & Outreach: Minimum Control Measure.” Accessed September 8, 2016. https://www.epa.gov/sites/production/files/2015-11/documents/fact2-3.pdf.

U.S. Environmental Protection Agency. 2016. “EPA Key Internet Tools for Watershed Groups.” Accessed September 8, 2016. https://www.epa.gov/urbanwaterspartners/epa-key-internet-tools-watershed-groups.

Virginia Department of Environmental Quality. No date. “Stroubles Creek: Water Quality Improvement Project.” Public domain. Accessed December 29, 2014. http://www.deq.virginia.gov/Portals/0/DEQ/Water/TMDL/strbinfo.pdf.

Virginia Department of Environmental Quality. No date. “A Landowner’s Guide to Spout Run.” Public domain. Accessed December 29, 2014. http://www.deq.virginia.gov/Portals/0/DEQ/Water/TMDL/ImplementationPlans/spoutguide.pdf.

Virginia Citizen Water Quality Monitoring Program Methods Manual. 2007. Virginia Department of Environmental Quality. Accessed December 29, 2014. http://www.deq.state.va.us/Portals/0/DEQ/Water/WaterQualityMonitoring/CitizenMonitoring/Citmon_Manual.pdf.


Virginia’s Runoff Reduction Method


Some states in the Chesapeake Bay watershed have required that developments implement low impact development practices.  Virginia’s approach is slightly different.  The Virginia Stormwater Management Program (VSMP) Permit Regulations include requirements for water quality and quantity based on post-development treatment volume.  This Runoff Reduction Method (VRRM) figures the runoff volume reduced by various stormwater BMPs and combines that with the ability of the BMP to remove pollutants.  By doing so, it takes into account the intensity of rain.  The VRRM relies on a three-step compliance procedure:

  • Apply site design practices to minimize impervious cover, grading, and loss of forest cover;
  • Apply runoff reduction (RR) practices; and
  • Compute pollutant removal (PR) by selected BMPs.

DEQ has developed a compliance spreadsheet for use by developers in selecting appropriate BMPs for either new development or retrofits.

Virginia Department of Environmental Quality. 2013. “Virginia Runoff Reduction Method.” Accessed September 3, 2014. http://www.vwrrc.vt.edu/swc/Virginia%20Runoff%20Reduction%20Method.html.

Hirshman, David, Kelly Collins and Tom Schueler. 2008. “Runoff Reduction Practices: A brief explanation of the research basis for assigning pollutant removal rates to BMPs.” In Technical Memorandum: The Runoff Reduction Method, 17. Ellicott City, MD: Center for Watershed Protection. Accessed December 28, 2014. http://www.vwrrc.vt.edu/swc/documents/pdf/CWP%20Technical%20Memo%20RRMethod_041808%20w_Apps.pdf.


Low Impact Development (LID)

Since the early 1980’s, land developers, particularly in fast-growing regions of the United States, have been required by states and municipalities to manage the stormwater runoff from the sites they develop.  Stormwater management has aimed at several specific goals:  protecting the biological and physical integrity of stream channels downstream from development sites; protection from frequent, localized flooding resulting from increased runoff volumes from the new impervious surfaces; and removing pollutants from the site runoff.  Other goals that have been added over the years are mimicking the rate of groundwater recharge that existed prior to development, and protecting streams and properties from extreme flood damage.

An array of BMPs have been developed and used over that period of time.  Probably the most-used practices have been filtering practices such as grass filter strips and channels, infiltration practices such as dry wells and infiltration trenches, permeable pavement, and impoundment practices such as wet and dry ponds and constructed wetlands.  These earlier practices were largely aimed at controlling the volume and discharge of runoff from the site, as well as providing treatment for the pollutants in the runoff.

In the last decade, a new type of BMP evolved, aimed at reducing the volume of stormwater runoff leaving the development site and, therefore, mimicking the hydrologic patterns that existed at a site before it was developed.  This is a way to minimize our “human footprint” or interference in natural processes.  These new kinds of practices have been labeled “low impact development” (LID) BMPs and include green roofs, bioretention or rain gardens, rooftop disconnection, dry swales and wet swales.  LID practices can be linked with Environmental Site Design (ESD) techniques, such as conserving open space and natural areas.   On lots, in residential streets and in parking areas, these significantly reduce imperviousness and overall development costs while providing greater protection of natural systems and processes.  Evaluations of various LID BMPs have been conducted to assist in the selection of appropriate BMPs.

While some of these BMPs are clearly aimed at site planning during the development phase, a good number of them are available as retrofit landscaping projects.  MGs are contacted regarding such BMPs as rooftop disconnection, swales, and of course, rain gardens; resources are provided to increase the effectiveness of educational outreach.

The movement toward use of LID practices has led to recognition that optimal protection of natural systems is achieved in land development projects by reducing runoff volume and mimicking the pre-development site hydrology.  This is a change from the previous concept of just focusing on treating pollution in the runoff and controlling its release from the site.

U.S. Environmental Protection Agency. 2016. “Urban Runoff: Low Impact Development.” Accessed September 8, 2016. https://www.epa.gov/polluted-runoff-nonpoint-source-pollution/urban-runoff-low-impact-development.

U.S. Environmental Protection Agency. 2016. “What is Green Infrastructure?” Accessed September 8, 2016. https://www.epa.gov/green-infrastructure/what-green-infrastructure.

U.S. Environmental Protection Agency. 2012. “Terminology of Low Impact Development.” Public domain. Accessed September 8, 2016. https://www.epa.gov/sites/production/files/2015-09/documents/bbfs2terms.pdf.

Low Impact Development Center, Inc. 2016. “Low Impact Development Center.” Accessed September 8, 2016. http://lowimpactdevelopment.org.

U.S. Environmental Protection Agency. 2014. “Encouraging Low Impact Development: Incentives Can Encourage Adoption of LID Practices in Your Community. Public domain. Accessed September 8, 2016. https://www.epa.gov/sites/production/files/2015-09/documents/bbfs7encouraging.pdf.

U.S. Environmental Protection Agency. 2014. “Soil Constraints and Low Impact Development: Careful Planning Helps LID Work in Clay Soils.” Public domain. Accessed September 8, 2016. https://www.epa.gov/sites/production/files/2015-09/documents/bbfs8clay_0.pdf.

Environmental Site Design


Environmental Site Design is an approach where a site is evaluated to determine the best layout of planned construction, or the best retrofits to an existing site for environmental considerations.  The goal is to arrange for a site plan that most closely resembles pre-development condition.  Techniques to enable a site to achieve the amount of runoff typical prior to development include low impact development (LID) for stormwater management; natural landscapes; minimizing impervious surfaces and increasing vegetated areas.  Sites are assessed for hydrology, soils and vegetation with the goal of capturing and treating runoff from land under development.  Environmental Site Design has overlapping goals and strategies with “green infrastructure,” sustainable design and LEEDâ and “better site design.”


Environmental Site Design (ESD) is usually considered at the outset of development plans.  However, understanding the principles and practices of ESD will allow the Advanced Master Gardener to educate the public on its benefits and/or assist homeowners and public land managers with implementing practices on their properties.


U.S. Environmental Protection Agency. 2014. “Green Infrastructure.” Accessed September 2, 2014. http://water.epa.gov/infrastructure/greeninfrastructure/index.cfm.


U.S. General Services Administration. 2014. “Sustainable Design.” Accessed December 28, 2014. http://www.gsa.gov/portal/content/104462.



Riparian buffers


Riparian buffers are strips of land along banks of rivers, streams and other waterways.  Among many benefits, their value lies in their ability to filter polluted runoff, slow and absorb water and as complex ecosystems that enhance the waterway communities.  Vegetation causes sediment and any potential pollutants adsorbed to the particle to be ‘caught’ and settle before reaching the waterway.  The buffers also stabilize banks, minimizing erosion.

The characteristics of the buffer – width, vegetation, soils, topography and hydrology – make a difference in the effectiveness of the buffer.  Found in such places as at the stream borders of agricultural fields and in Resource Protection Areas between development and streams, they can be enhanced or created on homeowners’ or communities’ land to lessen the amount of water leaving properties and improving water quality.

Gilliam, J.W., D.L. Osmond, and R.O. Evans. 1997. “Riparian Buffers: What are They and How Do They Work?” In Selected Agricultural Best Management Practices to Control Nitrogen in the Neuse River Basin. North Carolina Agricultural Research Service Technical Bulletin 311, North Carolina State University, Raleigh, NC. Accessed December 30, 2014. http://www.soil.ncsu.edu/publications/BMPs/buffers.html.

Klapproth, Julia C. and James E. Johnson. 2009. “Understanding the Science Behind Riparian Forest Buffers: Effects on Water Quality.” Virginia Cooperative Extension 420-151. Accessed December 30, 2014. https://pubs.ext.vt.edu/420/420-151/420-151.html.

Alliance for the Chesapeake Bay. 2014. “Riparian Buffers.” Accessed December 30, 2014. http://stormwater.allianceforthebay.org/take-action/structural-bmps/riparian-buffers/.