Zoning Practice — December 2006

Ask the Author

Here are reader questions answered by Lisa Nisenson, author of the the November 2006 Zoning Practice article "Stormwater Regulation and Urban Design."

Question from Pauline High, Franklin County, North Carolina:

I am in the process of developing a stormwater plan for a rural county. Currently, stormwater is being handled by another agency. What steps and advice do you have in trying to establish a management plan in regards to stormwater?

Answer from author Lisa Nisenson:

There are two main starting points: One deals with content and the other with administration.


North Carolina has well-established water rules that will influence how you write your stormwater management plan.

First, note that there are several areas to be included in a stormwater management plan: construction, post-construction and industrial. For land-use planning, the post-construction rules are likely to be closely aligned. Post-construction refers to stormwater management that is related to the site. The requirements typically look at the stormwater profile of a site before and after development, and designing practices to capture runoff on site. However, in areas with priority water concerns, other factors may influence management practices, such as pollutant loadings or contributions by a developer to large-scale stormwater projects. However, there are also rules other than stormwater regulations that may have requirements related to development and redevelopment. These can include watershed management requirements, Total Maximum Daily Load (TMDL requirements where urban runoff is considered one of the "loads" into impaired waterways), and habitat or fisheries requirements.

For your situation, as with anyone, this string of questions can help get you started:

1. Is my county or city covered under the stormwater rules?

There is a general answer and one specific to your state.

General: To find this out, you will need to find the state maps of areas covered under Phase II. You may either be automatically designated (i.e., your city or county met the threshold population and density criteria), or designated by the state. The best way to find out is to plug in the name of your state, "MS4" "NPDES." This will take you to the state home page, which will list both large MS4s (covered under Phase I) and medium and small MS4s. The state should identify which cities are covered under Phase II, as well as links to the general permit. Note that rural areas are more likely to be covered under Phase II, but may not be included in the regulations. However, it is helpful to get out ahead of the requirements, since fast-growing rural areas may be brought under regulation in the future.

North Carolina: North Carolina's road to Phase II has been a bit tumultuous, and as such, determining the county-level requirements can be complicated. North Carolina was one of the first states to tie land and water resources, in particular with the Neuse River rules (which may also affect Franklin County). However, the Phase II rules were challenged, which led to a special legislative session and rules in 2006. I would engage the county attorney, the public works department, and, if possible, someone from the state (EMC) or the University of North Carolina Environmental Finance Center. However, here are some pointers.

First, North Carolina's home page for Phase II is http://h2o.enr.state.nc.us/su/NPDES_Phase_II_Stormwater_Program.htm. Also see www.ncphase2sw.org/Post_Construction.htm.

The map of Phase II communities (http://h2o.enr.state.nc.us/su/documents/phase2_statewide.pdf) shows that a small portion of Franklin County is covered under Phase II, but that Franklin County as a whole is a "Phase II Tipped County" for post-construction requirements. See http://h2o.enr.state.nc.us/su/documents/PhaseII_Update_Map.pdf.

Power Point on new rules. A good over view and summary: www.efc.unc.edu/publications/Presentations/PhaseII2006Update.pdf

Model Ordinances. The state has two model ordinances (one applying to pre-2006 permits, and a second for post-2006 permits). It is worth going through these with the county attorney. The ordinance was written to allow communities to tie in several other stormwater-related aspects of environmental protection, including watershed planning and prevention of pollution via septic failure. The ordinance is posted on the water home page above.

Details. Sensitive Receiving Waters: The 2006 rules specify requirements for sensitive receiving waters, such as shellfish beds, trout stream, and nutrient-sensitive waters. Check to see if any apply. You may need to sit down and track where land development activity in the planning department may be a primary aspect of protecting or improving water quality. For example, in trout-sensitive waters, the elimination of shade near streams and the increase in dark pavement impact the temperature of stormwater runoff. Thus, your department may target land clearing rules or the configuration of parking to mitigate the risk of temperature inputs to streams.

Other Rules. See if you are covered under the Neuse River rules (www.unrba.org/aunrb.htm), and if the Watershed Water Supply rules apply (http://h2o.enr.state.nc.us/wswp/). If so, focus on those requirements. Also refer to the state's 303(d) list. It appears that Shelly Branch of Shelly Creek is listed. See if someone from the Tar River Conservancy can help identify the areas. You may also want to work with them if Franklin County wants to include offsets or land conservation in its stormwater program. It looks like a lot of easements are being made. You might as well see if you can credit them within your compliance program for NPDES.

High-density and low-density options. This language for looking at ordinances arose long ago for regulating water/land resources. For the stormwater rules, the important factor is that for the low-density option, natural treatment for stormwater is required, while for the high-density option, structural bumps are required. The word "density" often provokes a reaction among stakeholders, which may pose one challenge to planners. Another is that site impervious cover triggers the density rules. As such, the stormwater rules may be more about lot size than impervious cover. In addition, the wording may seem to preclude the use of natural stormwater systems in older, developed areas, even as many natural options are adopted in urban areas across the country. Finally, many of the natural systems are cheaper than structural practices, so keep an eye on whether the low/high-density rules begin to favor development further out where there is lots of land.

Clustering. The new North Carolina rules specifically allow "clustering." This term refers to new subdivision design that clusters development while leaving a portion of the subdivision undeveloped for purposes of ecoservices (i.e., infiltration). For planners, this is a great option where the county has mapped out future residential housing. However, if housing gets ahead of commercial development and services, the chain reaction of growth may not give intended results.

Design manuals. North Carolina's permit refers to design manuals. These manuals specify engineering requirements, design storms, and "menus" of practices that can be used. Because they are referenced in the permit, they are part of the regulatory structure. For planners, make sure that the design requirements match the desired planning and development goals. The design manual may include several chapters: one for rural, one for downtown redevelopment, another for subdivisions, etc. This may be a new concept for stormwater manual design (where the designs are often based solely on new greenfields development), but one worth pursuing.


General. While post-construction affects content, a stormwater management program involves development, implementation and enforcement. A good introductory article on gaining support can be found in the archives of Stormwater magazine. www.forester.net/sw_0103_plan.html

Some of the top challenges in developing a stormwater management program are:

  1. Financing the Program. Phase II was an unfunded mandate. As such, many localities are creating stormwater utilities to fund development and on-going operations for stormwater programs. Planning departments may be called in to help develop credits for on-site or innovative programs.
  2. Sharing Responsibility (especially when a new program is created by merging older programs). Part of the exercise may be evaluating existing programs to reduce rework. Because planning and development departments have a great deal of influence of the extent and placement of impervious surface – should be fully integrated into any stormwater management program.
  3. Synchronizing Planning and Compliance Efforts. Many planning efforts will parallel or overlap with stormwater program development. However, these efforts often have planning horizons, annual reporting, or permit renewal cycles that are not in sync. For planners, lining up comprehensive planning elements (especially visioning and outreach) with stormwater program development can save an enormous amount of work, but only if conducted jointly.
  4. Enforcement. Even in fully funded programs, maintenance of BMPs continues to be a top issue; once a BMP fails, receiving streams begin to suffer.
  5. Prioritizing Stormwater Problems. The list of stormwater impacts is likely to be much larger than resources or time can address in the short term. Thus, a small community may find the first step is gathering stakeholders to address high priority flooding, monitoring, water quality or "hotspot" locations.

The State of New York developed a "Stormwater for Local Officials" manual (www.dec.state.ny.us/website/dow/toolbox/ms4toolbox/local.html). It is specific to New York, though the structure is worth noting. See if your state (or state chapter of APA) has developed similar materials.

North Carolina-specific. Greensboro has a top-notch stormwater program worth copying. See www.stormwatersmart.org. For rural areas, the local NCSU Extension office may also be a resource.

The Land of Sky Regional Council and RiverLink developed a Fact Sheet on local program development:

As was mentioned above, the state included information on septic (or on-site) systems for waste disposal. Franklin County is likely to have a high percentage of on-site systems, plus the potential for more as the demand for hobby farms and retirement homes continues to grow. NCSU's Department of Biological and Agricultural Engineering may have resources (www.bae.ncsu.edu/).

Finally, the link to watershed planning should be exploited. Contacts include: the North Carolina Department of Biological and Agricultural Engineering's watershed effort: www.bae.ncsu.edu/programs/extension/wqg/ncwsheds.

Question from Charnelle Hicks, AICP, President, CH Planning Ltd.:

I am so happy that stormwater management is getting more recognition these days ... How can we as planners get the message to our elected officials that stormwater management is a planning issue as well as an engineering issue?

Answer from author Lisa Nisenson:

Getting elected officials to understand the planning implications requires an understanding of what motivates (or scares) them most. The good thing about stormwater is that it is so intertwined with other issues that the opportunities for framing an attention-grabbing message are abundant.

1. It always helps to have a federal mandate. The new stormwater regulations essentially forged planning a prominent place within the discipline of stormwater management. The professionals within EPA's Office of Water recognized two important, interlinking shifts in runoff control: one at the site level and the other at the suprasite level. At the site level, the new rules recognize that the public infrastructure cannot efficiently or effectively handle the cumulative runoff from each and every development site. The suprasite level, which might be thought of as the subwatershed, the neighborhood, a small city, or a district, is a new way of looking at a runoff profile for development. Note that these terms jumble together watershed planning and conventional land-use planning. A community will need ultimately to use the locally appropriate terms that fit the middle development layer between the site and the watershed or region. This level is discussed in more detail below.

2. The new rules are not only a federal mandate, but also a federal unfunded mandate. This means anyone (consultant, staff, or citizen activist) who can craft a response in terms of cost savings will get the most attention. Diverting 100 percent of the rainfall from every property into the public system is incredibly costly in the near and longer terms as watersheds build out. Thus, retaining water on-site means less burden on the public system they have been elected to safeguard.

In my opinion, the best financial argument goes to those local government officials pursuing growth management. An overall smaller development footprint is good for the watershed, and accommodating more growth on a smaller footprint lessens total runoff. Get to the officials pursuing smart growth, walkability, growth management, redevelopment, or quality growth (whatever the local phrase is), and you will hand them the stormwater issue. (The article listed several resources — contact me if you need copies).

3.  Some localities are unfortunately playing catch-up, so extra investment is needed in infrastructure since handling all stormwater on individual sites is impossible. Local officials must endure criticism of the "rain tax" or how the locality wants to tax a "Gift from God." Planners may need to help local officials develop responses on why the investment is needed. For instance, in areas prone to flooding, you may want to point out that rain is a gift until the soil is saturated. I used to live in Arlington, Virginia, where the clay soils and heavy rainfall would conspire to deliver about 2 inches of the "Gift" to my basement, not all of which fell within the boundaries of my property. Thus, one of the more eye-catching ways to frame stormwater management is "flood control." Actually, the better phrase may be "property protection." These examples are intended to stoke creative responses based on the local condition. In some areas trout streams, water-dependent industries, or scenery may be big issues. All of these can be threatened by the impacts of runoff.

4. Finally, grabbing the attention of any elected official requires framing the issue in terms of control. While the new mandates may be a pain in the neck, they also represent a new angle on their responsibility, and hence control. The new rules are to be implemented "by ordinance or other regulatory means," which translates in most places into land development regulations. Zoning, street dimensions, use mix, job location, school siting decisions, and density all dictate the ultimate degree of dispersal and coverage. These "middle level" decisions are made at the city, county, township and regional levels and are among the most difficult decisions that grace the agenda of planning and zoning sessions. Difficult decisions to deny sprawl zoning or add density now have additional support in the overall stormwater and flooding picture. (E.g., if we don't capture development demand on the existing footprint, where will development spread and how much more will the water flow?). The greatest unexplored control issue is across boundaries. Can dispersed development encouraged by outlying counties undermine the ability of cities to meet regulatory obligations? This is an age-old regulatory problem within water laws, now entwined with land development decisions.

As for the engineering question, if a locality looks to managing stormwater only as an engineering exercise, it is up to planners to explain why the locality will lose. The old way of site planning, as well as half-hearted implementation of the new rules, are exposing a gigantic myth in how we analyze the impacts of land development. I tend to call it the "False Science of the Site Plan."

For example, take a conventional subdivision. An engineer will be called in to estimate runoff and back-fit the site with Best Management Practices, such as a pond. The new green trend looks at the same site plan, but clusters the development to preserve a greater portion of the site as undeveloped. The job of the engineer now includes a comparison of the environmental "savings" of clustered over conventional design.

Now, let's scope up and look at this site in a different way. For many subdivisions, the main impact is not just runoff-related, but the chain reaction of impacts that arise when unplanned housing fuels growth in schools, services, transportation, and the like. Now, we are not only talking about on-site development cover, but a proliferation of development that has its roots not in engineering studies, but in retail feasibility studies, classroom crowding statistics, and level of service assessments for intersections. Whether the subdivision is conventional or clustered matters little; these impacts can overwhelm the environment. Thus, while the clustered subdivision scores an "A+" in site plan review with swales, open space, and a measure of trees saved, on the regional or watershed basis, it fails. Of course, there are many localities that have scoped out housing needs and how new single-family homes fit into the picture. This is usually in the comprehensive plan, where potential residents' needs, such as jobs, daily trip making, and services have been scouted out and woven into a long-term operating plan. This is also how conservation subdivisions, as part of the larger whole, can score well at both levels.

It boils down to a couple of challenges as we all go forward (in addition to those listed in the article):

1. The main problem in the "site plan engineering" for stormwater problem is not the "engineering" part, but the "site plan" part. This, of course, reflects how we measure any impact of a development project. However, as illustrated above, just looking at the site plan can give false answers.

2. We do not have readily available tools to measure the impacts at the two scales. Until these tools are developed, adopted, and used in each approval process, we will continue to degrade watersheds through each approved site plan.

3. The analysis above is not only engineering, but economic, transportation, and trend-driven. If a redevelopment project "saves" impervious cover, where would that cover have been? Does it need to be permanently offset? How can the benefits of bringing a mix of uses closer together be quantified? Is the comprehensive plan up to the task of assigning future development and preservation? Does the new as assessment treat landowners fairly? These are all economic development and planning questions that need to be coded into engineering specifications. Are we as planners and stormwater engineers up to the task?

Postscipt: One of the most widely cited, but least understood, analyses cross-translating impervious cover and zoning terms is a project by the George Washington University (GWU) for EPA's Brownfields office. In 2001, then EPA-Administrator Christine Todd Whitman summarized the study results by noting that each acre of redeveloped brownfields can translate into 4.5 acres of greenfields development avoided. This statistic is widely used in presentations, speeches, and PowerPoint presentations, but the study methodology is rarely dissected. This is unfortunate because the analysis reveals how the ever-increasing development footprint is dictated by zoning codes that are "improved" over time for new development. I encourage planners to look at this study and use the template to develop local methods to estimate new development versus redevelopment scenarios. Suppose a local redevelopment project is opposed due to stormwater concerns. Using the GWU methodology, a local planner can translate the redevelopment intensity and footprint into a new development footprint in a plausible location upstream. This is where the footprint differential lies and the new cover can be several times larger because of ever-increasing parking and setback requirements (including mandatory land set-asides or impervious surface coverage limitations). Have a stormwater engineer translate the new impervious cover into runoff volumes that eventually are piped into the same stream. Yes, it will be crude, and you may need two or three plausible locations to give a realistic view. However, it provides an example of the two-level assessment that needs to occur within a watershed to better evaluate development impacts.

See www.gwu.edu/~eem/Brownfields/project_report/report.htm.