Stormwater Atlas

regional

Regional and Site Constraints

Where national defaults must fork: climate, soils, geology, and receiving-water sensitivity.

ReviewedPrevalence 49%~292 manuals tagged14 citationsModel: heuristic+editorialRegional: arid_west, cold_climate, karst, coastal
Provisional practice synthesis for discussion — not a design manual or adopted regulation. Controlling state, regional, and MS4 criteria apply when more stringent. Verify citations against the linked jurisdiction manuals.

Practice

Climate and geologic forks appear throughout U.S. manuals: arid West capture and infiltration rules, humid East multi-storm peak matching, cold-climate freeze-thaw detailing, coastal freeboard and salinity, and karst or high-groundwater infiltration limits. Presenting humid-East defaults as universal national numbers misrepresents practice.

Regional design packages

Draft national guidance grounded in atlas practice — not a design manual or adopted regulation.

PackageSuggested national guidanceAtlas note
Arid WestLarger capture/retention depths; document infiltration limits and dust/TSS emphasisCapture-depth standards common in West manuals
Humid EastMulti-storm peak matching and WQv depth/percentile standardsDefault framing in many East/Midwest manuals
Cold climateAccount for frozen ground, snowmelt, and underdrain/plant detailingFreeze-thaw forks appear in northern manuals
Coastal / karst / high GWLimit infiltration credits; check tide, surge, and freeboardGeologic and coastal constraints are first-class in many locals

Guidance

Treat regional variants as first-class content. Identify arid West, humid East, cold climate, coastal, and karst or high-groundwater packages for capture volume, infiltration feasibility, and plantings. Require designers to document which regional package applies. Prefer local and state manuals when they define climate-specific criteria.

Regional notes

arid_west, humid_east, cold_climate, coastal, karst — each may change WQ depth, infiltration credit, freeze-thaw detailing, and outfall freeboard.

Open questions

How many climate bands to publish. Map or lookup method for assigning a site to a band.

References

Numbered footnotes for guidance clauses and atlas notes. Field-verified entries come from structured atlas evidence; corpus-pattern entries are keyword-matched excerpts.

  1. [1]CaliforniaCaliforniaCorpus patternpages 117-117
    “ry, Association of Monterey Bay Area Governments, Woodward-Clyde, Central Coast Regional Water Quality Control Board. July, 1998, Revised by California Coastal Commission, February 2002. Orange County Stormwater Program http://www.ocwatersheds.com/”
  2. [2]IndianaIndianaCorpus patternpages 564-564
    “s of six inches for commercial uses such as automobiles with no truck traffic). Regional Adaptations  In cold climates, the base of the stone reservoir should be below the frost line or the system should be designed to facilitate drainage of storm”
  3. [3]New York StateNew YorkCorpus patternpages 40-40
    “– Table 3.5 Watershed/Regional Selection Matrix SMP Group Sensitive Stream Aquifer Lakes Reservoir Estuary/Coastal Ponds Emphasize channel protection. Restrict in-stream practices. In trout”
  4. [4]MississippiMississippiCorpus patternpages 142-143
    “r recharge. Other design modifications may make this practice more effective in arid or cold climates. Partial Exfiltration In one design variation of the bioretention system, the underdrain is installed on only part of the bottom of the system”
  5. [5]MontanaMontanaCorpus patternpages 143-143
    “ssee Permanent Stormwater and Design Guidance Manual. December 2014. 9. Atlanta Regional Council. Georgia Stormwater Management Manual: Volume 2 Technical Handbook. [book auth.] AECOM et al. Chapter 4: Stormwater Best Management Practices. Atlanta,”
  6. [6]MinnesotaMinnesotaCorpus patternpages 816-816
    “for snow disposal sites. In Proceedings - Urban Drainage and Highway Runoff in Cold Climate, March 25-27, 2003, Riksgränsen, Sweden, pp.85-95. Wigington, P., C. Randall, And T. Grizzard. 1986. Accumulation of Selected Trace Metals in Soils of Urban Ru”
  7. [7]ConnecticutConnecticutCorpus patternpages 11-11
    “t guidance in the Manual also incorporates and/or references information from a regional stormwater retrofit manual that has been developed for New England.  Updated section on the appropriate use of proprietary stormwater BMPs (Chapter 11 - Propr”
  8. [8]California Department of Transportation (Caltrans)CaliforniaCorpus patternpages 7-7
    “roducts RUSLE2 Revised Universal Soil Loss Equation v2 RW Receiving Water RWQCB Regional Water Quality Control Board SMARTS Storm Water Multiple Application Reporting and Tracking System SS Settleable Solids SWMP Stormwater Management Program SWPPP”
  9. [9]City of NorfolkVirginiaCorpus patternpages 86-87
    “t. Slopes were calculated by applying the ArcGIS slope function to the Seamless Regional Digital Elevation Model documented in Appendix B of Hampton Roads Coastal Resources Technical Assistance Program Fiscal Year 2011-2012 3. The slope function in”
  10. [10]GeorgiaGeorgiaCorpus patternpages 178-178
    “ommunity must consider environ- mental factors such as flooding and hurricanes, regional factors such as proximity to the coast and presence of karst, and future growth condi- tions and patterns. In addition, a community must determine the best app”
  11. [11]West VirginiaWest VirginiaCorpus patternpages 293-293
    “p slopes. However, longitudinal slopes of 10% or less are recommended. RSC-6.3. Cold Climate and Winter Performance Many different kinds of salting and sanding materials are applied in West Virginia during winter conditions. These can clog the sand/woo”

Supporting jurisdictions

11 jurisdictions cited in this section (outline tags ~292 manuals; full atlas has ~299).

ca-casqa-municipalindiana-manualny-statems-state-vol2billings-mtmn-state-2008ct-stateca-caltrans-constructionnorfolk-vaga-statewest-virginia-manual