United States Office of Water EPA 833-F-99-004 Environmental Protection (4203) April 1999 Agency Fact Sheet 2.2 SEPA Storm Water Phase II Proposed Rule Fact Sheet Series Overview 1.0 - Storm Water Phase II Proposed Rule Overview Small MS4 Program 2.0 - Small MS4 Storm Water Program Overview 2.1 - Who's Covered? Designation and Waivers of Regulated Small MS4s 2.2 - Urbanized Areas: Definition and Description Minimum Control Measures 2.3 - Public Education and Outreach Minimum Control Measure 2.4 - Public Participation/ Involvement Minimum Control Measure 2.5 - Illicit Discharge Detection and Elimination Minimum Control Measure 2.6 - Construction Site Runoff Control Minimum Control Measure 2.7 - Post-Construction Runoff Control Minimum Control Measure 2.8 - Pollution Prevention/Good Housekeeping Minimum Control Measure 2.9 - Permitting and Reporting: The Process and Requirements 2.10 - Federal and State-Owned MS4s: Program Implementation Construction Program 3.0 - Construction Program Overview Industrial "No Exposure" 4.0 - Conditional No Exposure Exemption for Industrial Activity Storm Water Phase II Proposed Rule Urbanized Areas: Definition and Description This fact sheet is based on the Storm Water Phase II Proposed Rule. Therefore, the information provided herein is subject to change upon publication of the final Phase II rule in November 1999. A revised series of fact sheets will be provided at that time. A comprehensive list of the current fact sheets is in the text box at left. As discussed inFact Sheet 2.1, Who's Covered? Designation and Waivers of Regulated Small MS4s, the proposed Phase II regulations would cover all small municipal separate storm sewer systems (MS4s) located within an "urbanized area" (UA). Based on the 1990 Census, there are 405 UAs in the United States that cover 2 percent of total U.S. land area and contain approximately 63 percent of the Nation's population. These numbers include Puerto Rico - the only U.S. Territory with UAs. UAs constitute the largest and most dense areas of settlement. UA calculations delineate boundaries around these dense areas of settlement and, in doing so, identify the areas of concentrated development. UA designations are used for several purposes in both the public and private sectors. For example, the Federal Government has used UAs to calculate allocations for transportation funding, and some planning agencies and development firms use UA boundaries to help ascertain current, and predict future, growth areas. What Is an Urbanized Area (UA)? The Bureau of the Census determines UAs by applying a detailed set of published UA criteria (see 55 FR 42592, October 22, 1990) to the latest decennial census data. Although the full UA definition is complex, the Bureau of the Census' general definition of a UA, based on population and population density, is provided below. An urbanized area is a land area comprising one or more places ~ central place(s) ~ and the adjacent densely settled surrounding area ~ urban fringe ~ that together have a residential population of at least 50,000 and an overall population density of at least 1,000 people per square mile. The basic unit for delineating the UA boundary is the census block. Census blocks are based on visible physical boundaries, such as the city block, when possible, or on invisible political boundaries, when not. How an urbanized area is determined varies slightly on the geographic entity, be it a place, county, Federal Indian reservation, or minor civil division (towns and townships), as explained below: ~ Place. A "place," whether an incorporated place or a Census-designated place, is included in its entirety even if all of its census blocks are not densely settled. Therefore, this part of the UA determination is based on place boundaries. In rare cases (128 places), a place is not included in its entirety, but rather only partly included within the UA, usually due to the existence of large expanses of vacant or very sparsely populated territory within its incorporated area. ------- Fact Sheet 2.2 - Urbanized Areas: Definition and Description Page 2 ~ County/Federal Indian reservation. A county is included in its entirety only if all of its census blocks, based on the county's unincorporated area, meet the UA criteria. Unlike a place, a county is often "split" into urbanized and non-urbanized portions, with no regard for political boundaries. Only small MS4s in the urbanized portion of a split county would be automatically covered under the Phase II Proposed Rule. If a county or sewer district, for example, operates a small MS4 that runs throughout a split county, it would only be required to implement the storm water program in the portion of the county that is within the UA. The same situation applies to split Federal Indian reservations, as well as minor civil divisions (see below). ~ Minor Civil Division (towns & townships). Twenty states have functioning subdivisions of counties called minor civil divisions (MCDs). MCDs are towns or townships, depending on the State. Like a county, a MCD is included in its entirety only if all of its census blocks meet the urbanized area criteria. A MCD is often "split" into urbanized and non-urbanized portions, with no regard for political boundaries. Only small MS4s in the urbanized portion of a split MCD would be automatically covered under the storm water Phase II proposal. Where a small MS4 runs throughout a split MCD, the owner/operator of the small MS4 would only be responsible for implementing the storm water program in the portion of the MCD that is within the UA. How Can Status as a Regulated Small MS4 Be Determined? The drawing below (see Figure 1) is a simplified UA illustration that demonstrates the concept of UAs in relation to the proposed storm water Phase II regulations. The "urbanized area" includes within its boundaries incorporated places, a portion of a Federal Indian reservation, an entire MCD, a portion of another MCD, and portions of two counties. Any and all owners or operators of small MS4s located within the boundaries of the UA would be covered under the Phase II Proposed Rule, regardless of political boundaries. Owners and operators of small MS4s located outside of the UA would be subject to potential designation into the Phase IIMS4 program by the NPDES permitting authority. Once the concept of a UA is understood, the owner or operator can proceed to determining their location in relation to a UA. Figure 1 Pvvj Central Place o Incorporated Place Federal Indian Reservation (FIR) Unincorporated "Urbanized Area" Portion of a Town (MCD) or County Urbanized Area Town or Township as a functioning Minor Civil Division (MCD). An MCD is the primary subdivision of a County. County 1719D _ J ------- Fact Sheet 2.2 - Urbanized Areas: Definition and Description Page 3 Owners and operators of small MS4s can determine if they are located within a UA, and therefore covered by the Phase II storm water program as proposed, through the following two steps: — STEP 1 — Refer to a listing of incorporated places, MCDs, and counties in UAs. Such a listing, based on the 1990 Census, can be found in Appendix 6 in the preamble to the proposed rule, although it does not include MCDs or governmental entities already permitted under Phase I. A similar listing, based on the 2000 Census, may be published with the storm water general permit for regulated small MS4s. If a small MS4 is located in a listed incorporated place, then it would be covered by the Phase II program. If a small MS4 is not located in a listed incorporated place, but is located in a listed MCD or county, then the owner or operator of the small MS4 would need to follow step (2) below. (Note: Listings of Phase II incorporated places, MCDs, and counties located entirely or partially within a UA can be obtained from the EPA Office of Wastewater Management or downloaded from the OWM web site.) — STEP 2 — Some owners and operators of small MS4s may find their counties or MCDs on the list but not know, due to the occurrence of split counties and MCDs, if their systems are within the urbanized portion of the county or MCD. In such a case, they should contact one or more of the following institutions for more detailed information on the location of the UA boundary: ~ The State/NPDES Permitting Authority (may be the State or the U.S. EPA Region) Storm Water Coordinators: The NPDES permitting authority may be the State or the U.S. EPA Region. The Storm Water Coordinators for each U.S. EPA Region are listed in the For Additional Information section in Fact Sheet 2.9. These regional contacts can assist with UA information and provide the names of State storm water contacts. Regional and State contact information can also be obtained from the EPA Office of Wastewater Management. State Data Centers: Each State's Data Center receives listings of all entities that are located in UAs, as well as detailed maps and electronic files ofUA boundaries. The Bureau of the Census web site includes a list of contact names and phone numbers for the data centers in each State (www .census .gov/sdc/www/). State Planning/Economic/Transportation Agencies: These agencies typically use UAs to assess current development and forecast future growth trends and, therefore, should have detailed UA information readily available to help determine the exact UA boundaries in any given area. ~ County or Regional Planning Commissions/ Boards As with State agencies, these entities are likely to already have detailed UA data and maps to help determine UA boundaries. ~ The Bureau of the Census Urbanized Areas Staff: 301 457-1099 Web Site: www.census.gov The site provides information on purchasing UA maps and electronic files for use with computerized mapping systems. Obtain free UA cartographic boundary files (Arc/Info export format) for Geographical Information System (GIS) use at: www.census.gov: 80/geo/www/ cob/ua.html. UA Maps: Detailed UA maps are available for purchase with a $25 minimum order ($5 per map sheet). Each map sheet measures 36 by 42 inches. For prices and a listing of UAs, visit www.census.gov/mp/www/geo/msgeo 12.html. Order from the Department of Commerce, Bureau of the Census (MS 1921), P.O. Box 277943, Atlanta, GA 30384-7943 (Phone: 301 457-4100; Toll-free fax: 1-888-249-7295). ~ The Local Library (or State Data Center) for Book of UA Maps The following book contains small maps of each UA and detailed listings of all geographic entities located within them: 1990 Census of Population and Housing. Supplementary Reports. Urbanized Areas of the United States and Puerto Rico. 1990 CPH-S-1-2 (2 sections, sold as a set). The UA book also can be ordered from the Government Printing Office by calling 202 512-1800 (approximate cost is $56). ------- Fact Sheet 2.2 - Urbanized Areas: Definition and Description Page 4 How Will the Year 2000 Census Affect the Determination of Status as a Regulated Small MS4? he listing of incorporated places and counties located within UAs in the United States and Puerto Rico, found in Appendix 6 of the proposed rule, is based on the 1990 Census. New listings for UAs based on the 2000 Census are scheduled to be available by July or August of 2001. Once the official 2000 Census listings are published by the Bureau of the Census, owners or operators of small MS4s located within the revised boundaries of former 1990 UAs, or in any newly defined 2000 UAs, would be required to seek NPDES storm water permits. Additional automatic designations of small MS4s based on the Year 2000 Census and subsequent census years would be governed by the Bureau of the Census' definition of a UA in effect for that year and the UA boundaries determined as a result of the definition. Once a small MS4 is designated into the Phase II storm water program based on the UA boundaries, it would not be waived from the program if in a subsequent UA calculation the small MS4 is no longer within the UA boundaries. An automatically designated small MS4 will remain regulated unless, or until, it meets the criteria for a waiver (see Fact Sheet 2.1 for more information on the regulated small MS4 waiver option). Contact U.S. EPA Office of Wastewater Management • Phone : 202 260-5816 E-mail: SW2@epa.gov Internet: www.epa.gov/owm/sw2.htm Reference Documents Storm Water Phase II Proposed Rule Fact Sheet Series. Contact the U.S. EPA Water Resource Center at 202 260-7786 or at waterpubs@epa.gov Internet: www.epa.gov/owm/sw2.htm For Additional Information Storm Water Phase II Proposed Rule, published on Jan. 9, 1998 in the Federal Register (63 FR 1536). Internet: www.epa.gov/owm/sw2.htm ------- |