Read "Stormwater Retrofit Programs and Practices Through Third-Party Partnerships" at NAP.edu

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Suggested Citation: "Appendix B: Responses Aggregated by State." National Academies of Sciences, Engineering, and Medicine. 2025. Stormwater Retrofit Programs and Practices Through Third-Party Partnerships. Washington, DC: The National Academies Press. doi: 10.17226/29106.

APPENDIX B

Responses Aggregated by State

		3A. If you answered No to Question 3, Why not? (Select all that apply.)
2. Which DOT do you represent?	3. Does your DOT own or manage permanent stormwater facilities	They don’t exist	They are owned/managed by a local agency	They are owned/managed by another state agency	Other (Please specify)
Arizona	Yes
Arkansas	No	X
California	Yes
Colorado	Yes
Connecticut	Yes
Delaware	Yes
Florida	Yes				IN: INDOT is currently only working on our post-construction program for active construction sites. We have not addressed facility post-construction yet and are planning on doing it on a case-by-case basis going forward with each new CSGP.
Georgia	Yes
Hawaii	Yes
Idaho	Yes
Illinois	Yes
Indiana	No
Iowa	No		X		IA: These facilities are very limited at our DOT. The few that we have were most likely included in design by local public agency.
Kansas	Yes
Kentucky	Yes
Maine	Yes
Maryland	Yes
Massachusetts	Yes
Mississippi	No	X
Missouri	Yes
Montana	Yes
Nebraska	Yes
Nevada	Yes
New Hampshire	Yes
New Mexico	Yes
New York	Yes
North Carolina	Yes

Page 70 Bookmark

Suggested Citation: "Appendix B: Responses Aggregated by State." National Academies of Sciences, Engineering, and Medicine. 2025. Stormwater Retrofit Programs and Practices Through Third-Party Partnerships. Washington, DC: The National Academies Press. doi: 10.17226/29106.

North Dakota	Yes
Ohio	Yes
Oklahoma	No	X
Oregon	Yes
Pennsylvania	Yes
Rhode Island	Yes
South Carolina	Yes
South Dakota	No		X
Tennessee	No	X
Texas	Yes
Utah	Yes
Vermont	Yes
Virginia	Yes
Washington	Yes
Wisconsin	Yes

	4. Which agencies regulate your transportation facilities and require permanent stormwater facilities? (Select all that apply.)
	A. State regulatory agency	B. Federal EPA	C. U.S. Army Corps of Engineers	D. U.S. Fish and Wildlife Service	E. Other federal (Please specify)	F. The DOT has no permanent stormwater facilities
Arizona	X
Arkansas
California	X		X	X	X
Colorado	X	X
Connecticut	X	X	X	X
Delaware	X
Florida	X
Georgia	X		X	X
Hawaii	X
Idaho	X
Illinois	X
Indiana	X
Iowa
Kansas	X
Kentucky
Maine	X
Maryland	X
Massachusetts	X	X
Mississippi
Missouri	X
Montana	X
Nebraska	X
Nevada	X	X

Page 71 Bookmark

Suggested Citation: "Appendix B: Responses Aggregated by State." National Academies of Sciences, Engineering, and Medicine. 2025. Stormwater Retrofit Programs and Practices Through Third-Party Partnerships. Washington, DC: The National Academies Press. doi: 10.17226/29106.

New Hampshire	X	X
New Mexico	X	X
New York	X	X
North Carolina	X		X
North Dakota	X	X
Ohio	X
Oklahoma
Oregon	X			X	NMFS/NOAA
Pennsylvania	X
Rhode Island	X
South Carolina	X
South Dakota
Tennessee
Texas	X
Utah	X
Vermont	X	X
Virginia	X	X
Washington	X		X	X	NOAA
Wisconsin	X	X


	5. What type of separate storm sewer system (MS4 or TS4) permit does your DOT hold?	H. Other (Please Specify)	6. Does your DOT have a stormwater retrofit program where permanent stormwater facilities are constructed to reduce, minimize, or treat runoff from existing facilities?
Arizona	B. Statewide Phase 1 MS4		D. In name only
Arkansas
California	B. Statewide Phase 1 MS4	DE: We have both Phase 1 urbanized areas only AND Phase 2 MS4 urbanized areas only	A. Yes
Colorado	B. Statewide Phase 1 MS4		B. No
Connecticut	G. Phase 2 TS4		A. Yes
Delaware	H. Other (Please Specify)		A. Yes
Florida	H. Other (Please Specify)	FL: Both C and D	B. No
Georgia	D. Phase 2 MS4		B. No
Hawaii	D. Phase 2 MS4	HI: Phase 1 UA MS4 and Phase 2s MS4	A. Yes
Idaho	H. Other (Please Specify)	HI: Phase 1 UA MS4 and Phase 2s MS4	B. No
Illinois	D. Phase 2 MS4		B. No
Indiana	H. Other (Please Specify)	IN: Currently a Phase 2 MS4 but just filed LOI to become a Phase 1 TS4 by 2026	B. No
Iowa
Kansas	G. Phase 2 TS4		B. No
Kentucky
Maine	G. Phase 2 TS4		B. No
Maryland		MD: Other MDOT agencies hold different permits. SHA is Phase 1 MS4	A. Yes
Massachusetts	D. Phase 2 MS4		A. Yes
Mississippi
Missouri	E. Statewide Phase 1 TS4		A. Yes
Montana	D. Phase 2 MS4		A. Yes

Page 72 Bookmark

Suggested Citation: "Appendix B: Responses Aggregated by State." National Academies of Sciences, Engineering, and Medicine. 2025. Stormwater Retrofit Programs and Practices Through Third-Party Partnerships. Washington, DC: The National Academies Press. doi: 10.17226/29106.

Nebraska	G. Phase 2 TS4		B. No
Nevada	B. Statewide Phase 1 MS4		A. Yes
New Hampshire	D. Phase 2 MS4		A. Yes
New Mexico	D. Phase 2 MS4		A. Yes
New York	B. Statewide Phase 1 MS4		A. Yes
North Carolina	E. Statewide Phase 1 TS4		A. Yes
North Dakota	C. Phase 1 urbanized areas		B. No
Ohio	D. Phase 2 MS4		B. No
Oklahoma
Oregon	B. Statewide Phase 1 MS4		D. In name only
Pennsylvania	D. Phase 2 MS4		A. Yes
Rhode Island	D. Phase 2 MS4		A. Yes
South Carolina	E. Statewide Phase 1 TS4		B. No
South Dakota
Tennessee
Texas		TX: Other Statewide Phase 1 and Phase 2	B. No
Utah	B. Statewide Phase 1 MS4	TX: Other Statewide Phase 1 and Phase 2	B. No
Vermont	G. Phase 2 TS4		A. Yes
Virginia	D. Phase 2 MS4		A. Yes
Washington	H. Other (Please Specify)	WA: WSDOT MS4 (in Phase 1 and 2)	A. Yes
Wisconsin	G. Phase 2 TS4	WA: WSDOT MS4 (in Phase 1 and 2)	B. No

	6A. If you responded yes to question 6, what regulation motivates the establishment of this permanent stormwater facility retrofit program? (Select all that apply.)
	A. It’s included in the language of the DOT’s MS4/TS4 or other permit.	B. It’s included in a state statute or regulation.	C. It’s an operational decision by the DOT.	D. Add another option (Please specify)
Arizona
Arkansas
California	X
Colorado
Connecticut	X
Delaware				DE: Operational decision to comply with Water Quality Improvement requirements of MS4 permits
Florida
Georgia
Hawaii	X		X
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Maine
Maryland				MD: Retrofits are pursued to add SWM credit or MS4 restoration credit
Massachusetts	X			MA: EPA enforcement order

Page 73 Bookmark

Suggested Citation: "Appendix B: Responses Aggregated by State." National Academies of Sciences, Engineering, and Medicine. 2025. Stormwater Retrofit Programs and Practices Through Third-Party Partnerships. Washington, DC: The National Academies Press. doi: 10.17226/29106.

Mississippi
Missouri	X	X	X
Montana	X
Nebraska
Nevada	X
New Hampshire	X	X
New Mexico	X
New York	X			NY: Language in the MS4 permit has been taken from TMDL Implementation Plans.
North Carolina	X	X
North Dakota
Ohio				PennDOT’s MS4 permit requires certain pollutant load reductions from existing facilities, but the permit does not mandate how those reductions are achieved. Stormwater “retrofits” are in PennDOT’s “PRP Playbook,” but they have been minimally used to this point.
Oklahoma
Oregon
Pennsylvania
Rhode Island				RI: EPA/DOJ Consent Decree
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont	X	X		In response to TMDLs
Virginia				TMDL responsibilities
Washington	X		X	WA: Endangered Species Act Section 7
Wisconsin				WA: Endangered Species Act Section 7

	7. What triggers the construction of the permanent stormwater facility retrofits? (Select all that apply)
	A. Any new construction, regardless of project size	B. Any new construction with added capacity	C. Any new construction with substantial increased impervious area or substantial disturbed area	D. A plan or program identifying prioritized locations, unrelated to new construction	E. Treatment to address TMDL findings	F. The decision documents of NEPA studies	G. Other (Please specify)
Arizona		X	X	X
Arkansas
California					X		CA: Calif-added impervious surface greater than 10,000 sq ft; 401 permit requirements, significant trash generation areas, Areas of Special Biological Significance
Colorado							CO: No Retrofits MS4 PWQ Program
Connecticut	X			X
Delaware			X		X
Florida			X
Georgia							GDOT doesn’t have a trigger for retrofits. It is only done on a case-by-case basis. There is no program.
Hawaii			X
Idaho							N/A
Illinois							As-needed basis
Indiana							New CSGP only

Page 74 Bookmark

Suggested Citation: "Appendix B: Responses Aggregated by State." National Academies of Sciences, Engineering, and Medicine. 2025. Stormwater Retrofit Programs and Practices Through Third-Party Partnerships. Washington, DC: The National Academies Press. doi: 10.17226/29106.

Iowa
Kansas		X
Kentucky
Maine							ME: We have not undertaken a “retrofit” program as of yet
Maryland		X	X		X		ME: We have not undertaken a “retrofit” program as of yet
Massachusetts			X	X	X
Mississippi
Missouri	X		X		X
Montana			X
Nebraska			X
Nevada			X				NH: State: Project Size. EPA: MS4 source area
New Hampshire							NH: State: Project Size. EPA: MS4 source area
New Mexico		X	X	X			MS4 Permits
New York				X	X		NC: State administrative code (rules) related to nutrient load reduction strategies.
North Carolina				X	X
North Dakota						X	City MS4 Requirements
Ohio							We don’t have a retrofit program
Oklahoma							PA: Treatment to satisfy Pollutant Reduction Plan requirements in the MS4 permit.
Oregon				X
Pennsylvania
Rhode Island		X			X		EPA/DOJ Consent Decree
South Carolina		X			X		Areas of Sensitive Waterbodies
South Dakota
Tennessee
Texas							Edwards Aquifer Protection
Utah		X	X				UT: Any project that results in 1/2 acre or more of impervious surface
Vermont					X
Virginia					X		VA: Potentially for new construction if an existing facility is in place that we could retrofit to meet the needs of the new project. Seldom used.
Washington			X	X		X
Wisconsin			X

	8. What types of permanent stormwater facility retrofits does your DOT utilize? (Select all that apply.)
	A. Retention facilities	B. Flow-through facilities	C. Detention facilities	D. Proprietary stormwater treatment	E. Permeable pavements or pavement disconnection	F. Constructed wetlands	G. Land conservation	H. Stream restoration	I. Wetland mitigation	J. Trash racks in catch basins/inlets	K. Other (please specify)
Arizona	X	X	X	X
Arkansas
California	X	X	X		X					X	CA: Proprietary BMPs considered if no approved DOT BMPs exist
Colorado
Connecticut	X	X	X	X	X						CO: No MS4 retrofits program
Delaware	X	X	X		X	X	X				CO: No MS4 retrofits program

Page 75 Bookmark

Suggested Citation: "Appendix B: Responses Aggregated by State." National Academies of Sciences, Engineering, and Medicine. 2025. Stormwater Retrofit Programs and Practices Through Third-Party Partnerships. Washington, DC: The National Academies Press. doi: 10.17226/29106.

Florida	X	X	X	X
Georgia	X	X	X
Hawaii	X	X	X	X	X
Idaho											N/A
Illinois	X	X	X							X
Indiana											IN: All when triggered by CSGP
Iowa											IN: All when triggered by CSGP
Kansas											Grass-lined Swales
Kentucky											Grass-lined Swales
Maine											See #7
Maryland		X	X		X		X	X
Massachusetts	X	X	X		X	X			X	X	MA: Deep sumps in inlets
Mississippi
Missouri	X	X	X	X
Montana	X	X	X	X						X
Nebraska		X	X	X						X
Nevada	X	X	X	X	X	X			X
New Hampshire	X	X	X	X	X					X	NH: F-H are DoA404 mitigation
New Mexico	X	X	X	X		X	X	X	X	X
New York	X	X		X
North Carolina	X	X	X	X	X	X
North Dakota	X		X
Ohio											OH: We don’t have a retrofit program
Oklahoma
Oregon	X	X		X
Pennsylvania	X	X						X
Rhode Island		X		X	X
South Carolina	X	X	X	X				X	X
South Dakota
Tennessee
Texas											TX: None—No retrofit program
Utah			X								See below*
Vermont	X	X	X	X	X
Virginia	X	X	X	X	X		X	X	X
Washington	X	X	X	X		X
Wisconsin											No retrofits

^*Utah-We refer to retention ponds as those that fully retain and do not infiltrate. Our retention ponds are for contaminated stormwater and truck wash water at maintenance stations.

	9. How is the construction of permanent stormwater facility retrofits funded? (Select all that apply.)
	A. Included in the construction budget of larger transportation projects and not separately tracked.	B. Included in the construction budget of larger transportation projects, with a budget line item or other accounting measure that shows the funds are explicitly intended for permanent stormwater facilities.	C. A separate fund within the DOT budget that is deployed to construct permanent stormwater facilities within larger infrastructure projects.	D. A separate fund within the DOT budget that is deployed to construct stand-alone. permanent stormwater facility projects.	E. Other (Please specify)
Arkansas	X

Page 76 Bookmark

Suggested Citation: "Appendix B: Responses Aggregated by State." National Academies of Sciences, Engineering, and Medicine. 2025. Stormwater Retrofit Programs and Practices Through Third-Party Partnerships. Washington, DC: The National Academies Press. doi: 10.17226/29106.

California		X
Colorado					CDOT’s MS4 Permit does not specify requirements for retrofits.
Connecticut		X		X
Delaware	X			X
Florida	X
Georgia				X
Hawaii			X	X
Idaho					N/A
Illinois	X
Indiana					IN: Included as a pay item for all future CSGPs.
Iowa					IN: Included as a pay item for all future CSGPs.
Kansas	X
Kentucky
Maine					ME: When/If we do it, it will be funded through federal funds to manage TS4 program
Maryland	X				MS4/TMDL restoration funding
Massachusetts	X		X	X
Mississippi
Missouri	X
Montana	X				MT: Maintenance funding for BMP Retrofits
Nebraska	X
Nevada	X			X
New Hampshire	X
New Mexico		X
New York	X	X
North Carolina				X
North Dakota	X
Ohio					We don’t have a retrofit program
Oklahoma
Oregon				X
Pennsylvania	X
Rhode Island	X			X
South Carolina	X
South Dakota
Tennessee
Texas					None; see question 6
Utah	X
Vermont	X			X
Virginia	X	X			TMDL/MS4 program budget
Washington	X			X	See below*
Wisconsin					Not funded

^* Washington-Public-private partnerships (only a few now, but likely more coming)

Page 77 Bookmark

Suggested Citation: "Appendix B: Responses Aggregated by State." National Academies of Sciences, Engineering, and Medicine. 2025. Stormwater Retrofit Programs and Practices Through Third-Party Partnerships. Washington, DC: The National Academies Press. doi: 10.17226/29106.

	10. Does your DOT have any written guidance for third-party agreements for permanent stormwater facility retrofits?	Provided?	11. Does your DOT have any written guidance regarding the performance, inspection, operation, and maintenance of permanent stormwater facilities?	Provided?
Arizona	No		A. Only for DOT-owned facilities.	Yes
Arkansas
California	No		A. Only for DOT-owned facilities.	Yes
Colorado	No		B. Both for DOT-owned and facilities-owned	Yes
Connecticut	Yes		B. Both for DOT-owned and facilities-owned
Delaware	Yes	Yes	A. Only for DOT-owned facilities.	Yes
Florida	No		A. Only for DOT-owned facilities.	Yes
Georgia	No		A. Only for DOT-owned facilities.	Yes
Hawaii	No		A. Only for DOT-owned facilities.	Yes
Idaho	No		D. The DOT has no formal written guidance.
Illinois	No		A. Only for DOT-owned facilities.	Yes
Indiana	Yes		A. Only for DOT-owned facilities.	Yes
Iowa
Kansas	No		A. Only for DOT-owned facilities.	Yes
Kentucky
Maine	No		D. The DOT has no formal written guidance.
Maryland	No		A. Only for DOT-owned facilities.	Yes
Massachusetts	No		D. The DOT has no formal written guidance.
Mississippi
Missouri	No		A. Only for DOT-owned facilities.
Montana	No		A. Only for DOT-owned facilities.	Yes
Nebraska	No		A. Only for DOT-owned facilities.	Yes
Nevada	No		B. Both for DOT-owned and facilities-owned	Yes
New Hampshire	Yes		A. Only for DOT-owned facilities.
New Mexico	No		D. The DOT has no formal written guidance.
New York	No		D. The DOT has no formal written guidance.
North Carolina	No		A. Only for DOT-owned facilities.	Yes
North Dakota	No		D. The DOT has no formal written guidance.
Ohio	No		A. Only for DOT-owned facilities.	Yes
Oklahoma
Oregon	No		B. Both for DOT-owned and facilities-owned.	Yes
Pennsylvania	No		A. Only for DOT-owned facilities.	Yes
Rhode Island	No		A. Only for DOT-owned facilities.	Yes
South Carolina	No		D. The DOT has no formal written guidance.
South Dakota
Tennessee
Texas	No		A. Only for DOT-owned facilities.
Utah	No		A. Only for DOT-owned facilities.
Vermont	No		D. The DOT has no formal written guidance.
Virginia	No		A. Only for DOT-owned facilities.	Yes
Washington	No		B. Both for DOT-owned and facilities-owned.	Yes
Wisconsin	No		A. Only for DOT-owned facilities.	Yes

Page 78 Bookmark

Suggested Citation: "Appendix B: Responses Aggregated by State." National Academies of Sciences, Engineering, and Medicine. 2025. Stormwater Retrofit Programs and Practices Through Third-Party Partnerships. Washington, DC: The National Academies Press. doi: 10.17226/29106.


	12. When constructing or funding permanent stormwater facility retrofits, does your DOT design the facility to treat runoff from non-DOT sources?	12B. If your response to question 12 is A, Never, has your DOT ever considered or pursued constructing or funding permanent stormwater facility retrofits to treat runoff from non-DOT sources but the project was never completed?
Arizona	C. Occasionally
Arkansas
California	B. Rarely
Colorado	A. Never	No
Connecticut	C. Occasionally
Delaware	D. Routinely
Florida	C. Occasionally
Georgia	A. Never	No
Hawaii	C. Occasionally
Idaho	A. Never	No
Illinois	A. Never	No
Indiana	A. Never	Yes
Iowa
Kansas	A. Never	No
Kentucky
Maine	E. Always
Maryland	C. Occasionally
Massachusetts	B. Rarely
Mississippi
Missouri	A. Never	No
Montana	A. Never	No
Nebraska	A. Never	No
Nevada	B. Rarely
New Hampshire	D. Routinely
New Mexico	A. Never	No
New York	C. Occasionally
North Carolina	C. Occasionally
North Dakota	B. Rarely
Ohio	A. Never	No
Oklahoma
Oregon	B. Rarely
Pennsylvania	C. Occasionally
Rhode Island	D. Routinely
South Carolina	A. Never	No
South Dakota
Tennessee
Texas
Utah	A. Never	No
Vermont	A. Never	No
Virginia	C. Occasionally
Washington	C. Occasionally
Wisconsin	B. Rarely

Page 79 Bookmark

Suggested Citation: "Appendix B: Responses Aggregated by State." National Academies of Sciences, Engineering, and Medicine. 2025. Stormwater Retrofit Programs and Practices Through Third-Party Partnerships. Washington, DC: The National Academies Press. doi: 10.17226/29106.


	12A. If your response to question 12 is anything other than A, Never, which of the following best describes the reason for the construction and funding of permanent stormwater facility retrofits to treat non-DOT sources?
Arizona	B. Mandated by a regulator/local agency to treat flows as part of a permit condition/mitigation strategy to address impacts of trans. project.
Arkansas
California	F. Other: commingled runoff.
Colorado
Connecticut	A. Treating offsite flows to eliminate the need to treat other onsite flows that are less feasible to treat.
Delaware	C. Creation of water quality banking system.
Florida	D. Participation in a regional watershed water quality cooperative with other agencies or municipalities.
Georgia
Hawaii	C. Creation of water quality banking system.
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Maine	F. Other: Mandated by regulator but not to address impacts of transportation project.
Maryland	B. Mandated by a regulator/local agency to treat flows as part of a permit condition/mitigation strategy to address impacts of trans. project.
Massachusetts	A. Treating offsite flows to eliminate the need to treat other onsite flows that are less feasible to treat.
Mississippi
Missouri
Montana
Nebraska
Nevada	F. Other: Comingled flows sometimes require treatment of offsite flows in addition to the DOT flows.
New Hampshire	F. Other: Engineering purposes only. It just happens to flow into our system.
New Mexico
New York	A. Treating offsite flows to eliminate the need to treat other onsite flows that are less feasible to treat.
North Carolina	See below*
North Dakota	B. Mandated by a regulator/local agency to treat flows as part of a permit condition/mitigation strategy to address impacts of trans. project.
Ohio
Oklahoma
Oregon	D. Participation in a regional watershed water quality cooperative with other agencies or municipalities.
Pennsylvania	D. Participation in a regional watershed water quality cooperative with other agencies or municipalities.
Rhode Island	A. Treating offsite flows to eliminate the need to treat other onsite flows that are less feasible to treat.
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia	F. Other: TMDL projects.
Washington	B. Mandated by a regulator/local agency to treat flows as part of a permit condition/mitigation strategy to address impacts of trans. project.
Wisconsin	A. Treating offsite flows to eliminate the need to treat other onsite flows that are less feasible to treat.

^* North Carolina-F. Other-NCDOT’s 2022 NPDES permit renewal removed the requirement for retrofit SCMs to treat DOT runoff. Therefore, if NCDOT has a cooperating non-DOT partner we will on occasion build a retrofit treating non-DOT runoff if the arrangement is mutually beneficial between the parties. In some cases, this arrangement can be part of a coordinated watershed restoration plan and other times not.

Page 80 Bookmark

Suggested Citation: "Appendix B: Responses Aggregated by State." National Academies of Sciences, Engineering, and Medicine. 2025. Stormwater Retrofit Programs and Practices Through Third-Party Partnerships. Washington, DC: The National Academies Press. doi: 10.17226/29106.


	13 and 3B. When your DOT works within the boundaries of other MS4 permittees (municipalities, counties, etc.), which MS4/TS4 permit requirements are controlling for improvements constructed by your DOT?
Arizona	A. State DOT MS4/TS4 permit requirements
Arkansas	A. State DOT MS4/TS4 permit requirements
California	C. More stringent, regardless if it is the DOT or underlying requirements
Colorado	D. Varies dependent upon situation
Connecticut	B. Underlying municipality MS4 permit requirements
Delaware	D. Varies dependent upon situation
Florida	D. Varies dependent upon situation
Georgia	A. State DOT MS4/TS4 permit requirements
Hawaii	A. State DOT MS4/TS4 permit requirements
Idaho	D. Varies dependent upon situation
Illinois	A. State DOT MS4/TS4 permit requirements
Indiana	D. Varies dependent upon situation
Iowa	D. Varies dependent upon situation
Kansas	A. State DOT MS4/TS4 permit requirements
Kentucky
Maine	D. Varies dependent upon situation
Maryland	A. State DOT MS4/TS4 permit requirements
Massachusetts	A. State DOT MS4/TS4 permit requirements
Mississippi	A. State DOT MS4/TS4 permit requirements
Missouri	D. Varies dependent upon situation
Montana	C. More stringent, regardless if it is the DOT or underlying requirements
Nebraska	A. State DOT MS4/TS4 permit requirements
Nevada	A. State DOT MS4/TS4 permit requirements
New Hampshire	A. State DOT MS4/TS4 permit requirements
New Mexico	C. More stringent, regardless if it is the DOT or underlying requirements
New York	D. Varies dependent upon situation
North Carolina	A. State DOT MS4/TS4 permit requirements
North Dakota	B. Underlying municipality MS4 permit requirements
Ohio	A. State DOT MS4/TS4 permit requirements
Oklahoma	B. Underlying municipality MS4 permit requirements
Oregon	C. More stringent, regardless if it is the DOT or underlying requirements
Pennsylvania	A. State DOT MS4/TS4 permit requirements
Rhode Island	C. More stringent, regardless if it is the DOT or underlying requirements
South Carolina	A. State DOT MS4/TS4 permit requirements
South Dakota	A. State DOT MS4/TS4 permit requirements
Tennessee	A. State DOT MS4/TS4 permit requirements
Texas
Utah	A. State DOT MS4/TS4 permit requirements

Page 81 Bookmark

Suggested Citation: "Appendix B: Responses Aggregated by State." National Academies of Sciences, Engineering, and Medicine. 2025. Stormwater Retrofit Programs and Practices Through Third-Party Partnerships. Washington, DC: The National Academies Press. doi: 10.17226/29106.

Vermont	A. State DOT MS4/TS4 permit requirements
Virginia	D. Varies dependent upon situation
Washington	D. Varies dependent upon situation
Wisconsin	A. State DOT MS4/TS4 permit requirements


	14. What approximate percentage of your DOT permanent stormwater facilities have been constructed with third-party partners?	15. What approximate percentage of your DOT permanent stormwater facilities are operated or maintained with third-party partners?	16. Are your DOT third-party partners primarily located in … ?
Arizona	A. 0%	A. 0%	A. Urban areas
Arkansas
California	B. 1%–10%	B. 1%–10%	C. High-priority watersheds
Colorado	D. 21%–30%	D. 21%–30%	A. Urban areas
Connecticut	B. 1%–10%	B. 1%–10%	A. Urban areas
Delaware	B. 1%–10%	B. 1%–10%	D. Randomly distributed
Florida	B. 1%–10%	C. 11%–20%	A. Urban areas
Georgia	A. 0%	B. 1%–10%	A. Urban areas
Hawaii	B. 1%–10%	B. 1%–10%	A. Urban areas
Idaho	A. 0%	A. 0%	E. We have no third-party partners
Illinois	A. 0%	A. 0%	A. Urban areas
Indiana
Iowa
Kansas	A. 0%	A. 0%	E. We have no third-party partners
Kentucky
Maine	B. 1%–10%	A. 0%	E. We have no third-party partners
Maryland	A. 0%	A. 0%	E. We have no third-party partners
Massachusetts	B. 1%–10%	B. 1%–10%	B. Uniformly throughout the state
Mississippi
Missouri	A. 0%	A. 0%	E. We have no third-party partners
Montana	A. 0%	A. 0%	E. We have no third-party partners
Nebraska	A. 0%	E. 31%–50%	A. Urban areas
Nevada	B. 1%–10%	B. 1%–10%	C. High-priority watersheds
New Hampshire	B. 1%–10%	A. 0%	E. We have no third-party partners
New Mexico	A. 0%	A. 0%	A. Urban areas
New York	B. 1%–10%	B. 1%–10%	C. High-priority watersheds
North Carolina	B. 1%–10%	B. 1%–10%	A. Urban areas
North Dakota	A. 0%	A. 0%	E. We have no third-party partners
Ohio	A. 0%	A. 0%	E. We have no third-party partners
Oklahoma
Oregon	B. 1%–10%	B. 1%–10%	A. Urban areas
Pennsylvania	B. 1%–10%	B. 1%–10%	D. Randomly distributed
Rhode Island	B. 1%–10%	B. 1%–10%	C. High-priority watersheds

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Suggested Citation: "Appendix B: Responses Aggregated by State." National Academies of Sciences, Engineering, and Medicine. 2025. Stormwater Retrofit Programs and Practices Through Third-Party Partnerships. Washington, DC: The National Academies Press. doi: 10.17226/29106.

South Carolina	C. 11%–20%	A. 0%	A. Urban areas
South Dakota
Tennessee
Texas
Utah
Vermont	B. 1%–10%	B. 1%–10%	A. Urban areas
Virginia	F. 51%–100%	E. 31%–50%	A. Urban areas
Washington	B. 1%–10%	A. 0%	A. Urban areas
Wisconsin	B. 1%–10%	B. 1%–10%	A. Urban areas

	17. What type of third-party partners does your DOT have? (Select all that apply.)
	A. Municipalities	B. Counties	C. Special districts or other quasi-government agencies	D. Other state agencies	E. Federal agencies	F. Private businesses	G. Private non-profit organization	H. Schools or universities	I. The DOT has no third-party partners	J. None of these options apply
Arizona	X	X	X			X
Arkansas
California	X	X	X	X	X		X
Colorado	X	X
Connecticut	X			X		X	X
Delaware	X	X				X		X
Florida	X	X	X
Georgia	X
Hawaii		X				X
Idaho										X
Illinois	X	X
Indiana
Iowa
Kansas	X	X
Kentucky
Maine										X
Maryland										X
Massachusetts	X
Mississippi									X
Missouri									X
Montana	X	X
Nebraska	X
Nevada	X	X	X			X
New Hampshire										X
New Mexico									X
New York				X
North Carolina	X			X			X	X
North Dakota									X

Page 83 Bookmark

Suggested Citation: "Appendix B: Responses Aggregated by State." National Academies of Sciences, Engineering, and Medicine. 2025. Stormwater Retrofit Programs and Practices Through Third-Party Partnerships. Washington, DC: The National Academies Press. doi: 10.17226/29106.

Ohio							X
Oklahoma
Oregon	X	X	X	X
Pennsylvania	X
Rhode Island	X		X			X
South Carolina	X	X
South Dakota
Tennessee
Texas
Utah	X	X
Vermont	X
Virginia					X
Washington	X	X				X
Wisconsin	X

		19. Has your DOT used any of the following approaches to participate in offsite flow permanent stormwater facilities RETROFIT projects, not new development? In this survey, we are primarily interested in water quality treatment facilities, not flow reduction facilities. (Select all that apply.)
	18. What best describes your DOT’s experience on the construction and/or funding of offsite flow permanent stormwater facility retrofits that provide offsite flow (see Appendix A for full question).	A. The DOT distributes funds to a local agency to pay for the construction and operation of the facility by that local agency and eliminates any active participation by the DOT.	B. The DOT partners with a local agency to construct and operate regional facilities with shared responsibilities defined in a third-party agreement.	C. The DOT pays their MS4/TS4 permitting agency or other statewide or regional authority a cash in lieu payment that is used to construct o site permanent stormwater facilities that might or might not directly treat DOT runoff. The cash in lieu payments are used to satisfy the DOT’ s permanent stormwater quality permit requirements	D. The DOT constructs and/or funds offsite permanent stormwater facilities that accept offsite flows and uses the treatment benefit to replace onsite treatment requirements in other parts of their transportation system.	E. None of these options apply.
Arizona	C. No experience					X
Arkansas
California	A. Considerable experience	X		X	X
Colorado	C. No experience					X
Connecticut	C. No experience					X
Delaware	B. Limited experience		X
Florida	B. Limited experience	X	X		X
Georgia	C. No experience					X
Hawaii	B. Limited experience				X
Idaho	C. No experience					X
Illinois	B. Limited experience					X
Indiana
Iowa
Kansas	C. No experience					X
Kentucky
Maine	C. No experience					X
Maryland
Massachusetts	B. Limited experience					X
Mississippi
Missouri	C. No experience					X
Montana	C. No experience					X
Nebraska	C. No experience					X
Nevada	B. Limited experience					X

Page 84 Bookmark

Suggested Citation: "Appendix B: Responses Aggregated by State." National Academies of Sciences, Engineering, and Medicine. 2025. Stormwater Retrofit Programs and Practices Through Third-Party Partnerships. Washington, DC: The National Academies Press. doi: 10.17226/29106.

New Hampshire	B. Limited experience				X
New Mexico	C. No experience				X
New York	B. Limited experience			X
North Carolina	B. Limited experience		X
North Dakota	C. No experience				X
Ohio	C. No experience				X
Oklahoma
Oregon	B. Limited experience		X
Pennsylvania	B. Limited experience		X	X
Rhode Island	A. Considerable experience	X		X
South Carolina	C. No experience				X
South Dakota
Tennessee
Texas
Utah	C. No experience				X
Vermont	B. Limited experience				X
Virginia	C. No experience				X
Washington	B. Limited experience	X
Wisconsin	B. Limited experience				X

	20. Has your DOT used any of the following approaches to participate in offsite flow permanent stormwater facilities FOR NEW DEVELOPMENT, not retrofits? In this survey, we are primarily interested in water quality treatment facilities, not flow reduction facilities. (Select all that apply.)
	A. The DOT distributes funds to a local agency to pay for the construction and operation of the facility by that local agency and eliminates any active participation by the DOT.	B. The DOT partners with a local agency to construct and operate regional facilities with shared responsibilities defined in a third-party agreement.	C. The DOT pays their MS4/TS4 permitting agency or other statewide or regional authority a cash in lieu payment that is used to construct offsite permanent stormwater facilities that might or might not directly treat DOT runoff.	D. The DOT constructs and/or funds offsite permanent stormwater facilities that accept offsite flows and uses the treatment benefit to replace onsite treatment requirements in other parts of their transportation system.	E. None of these options apply.
Arizona		X
Arkansas					X
California	X		X	X
Colorado	X	X	X
Connecticut					X
Delaware				X
Florida	X	X		X
Georgia					X
Hawaii				X
Idaho					X
Illinois					X
Indiana
Iowa					X
Kansas					X
Kentucky
Maine					X
Maryland
Massachusetts					X

Page 85 Bookmark

Suggested Citation: "Appendix B: Responses Aggregated by State." National Academies of Sciences, Engineering, and Medicine. 2025. Stormwater Retrofit Programs and Practices Through Third-Party Partnerships. Washington, DC: The National Academies Press. doi: 10.17226/29106.

Mississippi				X
Missouri				X
Montana				X
Nebraska				X
Nevada				X
New Hampshire				X
New Mexico				X
New York				X
North Carolina				X
North Dakota				X
Ohio	X
Oklahoma				X
Oregon			X
Pennsylvania				X
Rhode Island	X		X
South Carolina				X
South Dakota				X
Tennessee				X
Texas
Utah				X
Vermont				X
Virginia				X
Washington				X
Wisconsin		X

	21. Regardless of your answer to questions 19 and 20, check any of the approaches that your DOT has considered to construct offsite flow permanent stormwater facilities. In this survey, we are primarily interested in water quality treatment facilities, not flow reduction facilities. (Select all that apply.)
	A. The DOT distributes funds to a local agency to pay for the construction and operation of the facility by that local agency and eliminates any active participation by the DOT.	B. The DOT partners with a local agency to construct and operate regional facilities with shared responsibilities defined in a third-party agreement.	C. The DOT pays their MS4/TS4 permitting agency or other statewide or regional authority a cash in lieu payment that is used to construct offsite permanent stormwater facilities that might or might not directly treat DOT runoff.	D. The DOT constructs and/or funds offsite permanent stormwater facilities that accept offsite flows and uses the treatment benefit to replace onsite treatment requirements in other parts of their transportation system.	E. None of these options apply.
Arizona		X
Arkansas					X
California	X		X	X
Colorado				X
Connecticut		X		X
Delaware	X	X	X	X
Florida	X	X		X
Georgia	X		X
Hawaii				X
Idaho					X
Illinois					X
Indiana
Iowa

Page 86 Bookmark

Suggested Citation: "Appendix B: Responses Aggregated by State." National Academies of Sciences, Engineering, and Medicine. 2025. Stormwater Retrofit Programs and Practices Through Third-Party Partnerships. Washington, DC: The National Academies Press. doi: 10.17226/29106.

Kansas					X
Kentucky
Maine					X
Maryland
Massachusetts					X
Mississippi
Missouri					X
Montana					X
Nebraska					X
Nevada	X	X		X
New Hampshire					X
New Mexico					X
New York				X
North Carolina	X	X
North Dakota					X
Ohio	X
Oklahoma
Oregon	X	X		X
Pennsylvania	X	X	X	X
Rhode Island	X			X
South Carolina					X
South Dakota
Tennessee
Texas
Utah					X
Vermont		X		X
Virginia					X
Washington	X	X	X	X
Wisconsin		X

	22. In partnering with another agency on offsite flow permanent stormwater facilities, what are the most important ingredients for success that your DOT has experienced? (Select all that apply.)
	A. Clearly defined responsibilities in the third-party agreement	B. Partnering with an agency that is well equipped to meet their commitments	C. A symbiotic relationship between the partners (i.e., each brings something the other needs)	D. Contingency planning for when things don’t go as planned	E. Staff and executive buy-in on both sides of the partnership	F. A formal mechanism to make the agreement permanent or ensure it outlives the current staff	G. Other (Please Specify)
Arizona	X					X
Arkansas
California	X	X	X	X	X	X	CA: Buy-in from regulators to grant compliance credits
Colorado						X	IGA
Connecticut	X	X		X		X
Delaware	X	X	X	X	X	X
Florida	X	X	X	X	X	X
Georgia		X	X		X

Page 87 Bookmark

Suggested Citation: "Appendix B: Responses Aggregated by State." National Academies of Sciences, Engineering, and Medicine. 2025. Stormwater Retrofit Programs and Practices Through Third-Party Partnerships. Washington, DC: The National Academies Press. doi: 10.17226/29106.

Hawaii	X	X	X		X	X
Idaho							N/A
Illinois							N/A
Indiana
Iowa
Kansas	X	X			X	X
Kentucky
Maine							ME: We do not have any offsite flow permanent sw facilities that we partner for
Maryland
Massachusetts	X
Mississippi
Missouri
Montana	X	X				X
Nebraska						X
Nevada	X					X
New Hampshire						X	Maintenance agreements
New Mexico							NM: No offsite flow permanent facilities
New York		X	X			X	NM: No offsite flow permanent facilities
North Carolina	X	X	X		X	X
North Dakota						X
Ohio					X
Oklahoma
Oregon	X
Pennsylvania	X	X			X	X
Rhode Island	X	X	X
South Carolina
South Dakota
Tennessee
Texas
Utah	X					X
Vermont	X	X		X		X
Virginia							N/A
Washington	X	X	X	X	X	X	Legal authority to partner
Wisconsin	X	X			X	X

	23. In partnering with a third party on offsite flow permanent stormwater facilities, what are the obstacles to a successful partnership that your DOT has experienced? (Select all that apply.)
	A. Lack of funding from the third-party partner	B. Different vision as to what constitutes good implementation of the technology between the DOT and the third-party partner	C. Varying standards and permit requirements between the DOT and the third-party partner	D. Difficulty in identifying who is the lead partner—the DOT or the third-party partner	E. Agreements that are forgotten with staff turnover	F. None of these options apply.
Arizona			X	X	X
Arkansas
California	X		X		X

Page 88 Bookmark

Suggested Citation: "Appendix B: Responses Aggregated by State." National Academies of Sciences, Engineering, and Medicine. 2025. Stormwater Retrofit Programs and Practices Through Third-Party Partnerships. Washington, DC: The National Academies Press. doi: 10.17226/29106.

Colorado	X	X	X	X	X
Connecticut			X		X
Delaware	X	X		X
Florida	X	X		X	X
Georgia	X	X	X
Hawaii		X	X	X	X
Idaho						X
Illinois						X
Indiana
Iowa
Kansas		X	X	X	X
Kentucky
Maine						X
Maryland
Massachusetts						X
Mississippi
Missouri
Montana					X
Nebraska						X
Nevada	X		X
New Hampshire						X
New Mexico						X
New York						X
North Carolina		X
North Dakota					X
Ohio			X
Oklahoma
Oregon		X	X		X
Pennsylvania	X		X
Rhode Island		X	X
South Carolina
South Dakota
Tennessee
Texas
Utah						X
Vermont						X
Virginia						X
Washington	X		X
Wisconsin	X				X

Page 89 Bookmark

Suggested Citation: "Appendix B: Responses Aggregated by State." National Academies of Sciences, Engineering, and Medicine. 2025. Stormwater Retrofit Programs and Practices Through Third-Party Partnerships. Washington, DC: The National Academies Press. doi: 10.17226/29106.

	24. How does your DOT ensure that third-party agreements for permanent stormwater improvements are memorialized so that commitments made for construction, operations, maintenance, and stormwater permit compliance continue to be met in the decades ahead?
	A. Rely on staff and institutional memory	B. Record document as encumbrance on property at county clerk/deed registry/etc.	C. Use of GIS or other DOT-based database to track	D. Memorandum of Agreement	E. Memorandum of Understanding	F. E-mail or Letter in File	G. The DOT is still seeking a suitable method	H. Other (Please Specify)
Arizona	X		X	X	X
Arkansas
California	X		X	X				CA: Approval from Regional or State Water Boards, third-party agreement and sharing credit
Colorado			X
Connecticut					X
Delaware		X		X
Florida				X	X			Joint participation agreement
Georgia				X		X
Hawaii				X	X
Idaho								N/A
Illinois								N/A
Indiana
Iowa
Kansas		X	X	X	X	X	X
Kentucky
Maine	X					X
Maryland
Massachusetts								MA: Owner of stormwater improvement identified in project specific O&M plan submitted with permit applications
Mississippi
Missouri
Montana				X			X
Nebraska				X
Nevada			X	X	X
New Hampshire								NH: Any maintenance of third-party facility will be regulated by the state DES or EPA, not DOT
New Mexico		X		X	X
New York			X			X	X
North Carolina			X	X
North Dakota				X	X
Ohio		X
Oklahoma
Oregon	X			X			X
Pennsylvania			X				X
Rhode Island			X	X			X
South Carolina
South Dakota
Tennessee
Texas
Utah				X
Vermont			X	X				Maintenance agreements
Virginia				X	X	X
Washington		X	X	X	X
Wisconsin				X

Page 90 Bookmark

Suggested Citation: "Appendix B: Responses Aggregated by State." National Academies of Sciences, Engineering, and Medicine. 2025. Stormwater Retrofit Programs and Practices Through Third-Party Partnerships. Washington, DC: The National Academies Press. doi: 10.17226/29106.

	25. This synthesis will also include case examples discussing current state DOT–third-party permanent stormwater retrofit partnerships. During the development of the case examples, additional follow-up questions will be required to develop a better understanding of current approaches to these state DOT–third-party partnerships. DOTs participating in the case examples will be provided with an opportunity to review the case example.	26. You have completed the survey. To submit your answers, click “Submit” below and your responses will be finalized. Thank you for participating.
Arizona	C. No, I am not willing to participate in a follow-up interview.
Arkansas
California	B. Yes, I am willing to participate and also recommend inviting my co-worker.
Colorado	C. No, I am not willing to participate in a follow-up interview.
Connecticut	C. No, I am not willing to participate in a follow-up interview.
Delaware	B. Yes, I am willing to participate and also recommend inviting my co-worker.
Florida	A. Yes, I am willing to participate in a follow-up interview.
Georgia	A. Yes, I am willing to participate in a follow-up interview.
Hawaii	A. Yes, I am willing to participate in a follow-up interview.
Idaho	C. No, I am not willing to participate in a follow-up interview.
Illinois	C. No, I am not willing to participate in a follow-up interview.
Indiana
Iowa
Kansas	A. Yes, I am willing to participate in a follow-up interview.
Kentucky
Maine	C. No, I am not willing to participate in a follow-up interview.
Maryland
Massachusetts	C. No, I am not willing to participate in a follow-up interview.
Mississippi
Missouri	C. No, I am not willing to participate in a follow-up interview.
Montana	C. No, I am not willing to participate in a follow-up interview.
Nebraska	C. No, I am not willing to participate in a follow-up interview.
Nevada	A. Yes, I am willing to participate in a follow-up interview.
New Hampshire	B. Yes, I am willing to participate and also recommend inviting my co-worker.
New Mexico	C. No, I am not willing to participate in a follow-up interview.
New York	A. Yes, I am willing to participate in a follow-up interview.
North Carolina	B. Yes, I am willing to participate and also recommend inviting my co-worker.
North Dakota	C. No, I am not willing to participate in a follow-up interview.
Ohio	C. No, I am not willing to participate in a follow-up interview.
Oklahoma
Oregon	B. Yes, I am willing to participate and also recommend inviting my co-worker.
Pennsylvania	A. Yes, I am willing to participate in a follow-up interview.
Rhode Island	B. Yes, I am willing to participate and also recommend inviting my co-worker.
South Carolina
South Dakota
Tennessee
Texas
Utah	C. No, I am not willing to participate in a follow-up interview.
Vermont	B. Yes, I am willing to participate and also recommend inviting my co-worker.
Virginia	C. No, I am not willing to participate in a follow-up interview.
Washington	C. No, I am not willing to participate in a follow-up interview.
Wisconsin	C. No, I am not willing to participate in a follow-up interview.