527 STORMWATER MANAGEMENT: USE OF OFF-SITE RETENTION THROUGH THE IN-LIEU FEE OR STORMWATER RETENTION CREDITS

527.1 For a site that undergoes a major regulated project and has an Off-Site Retention Volume (Offv) requirement, a person shall use off-site retention to comply with each gallon of the Offv requirement each year until the Department terminates or suspends the Offv requirement pursuant to §§ 527.20–527.24.

527.2 The Department shall track the use of off-site retention to comply with an Offv requirement.

527.3 A person shall comply with an Offv requirement no later than the Offv compliance date, which begins and recurs annually on the earlier of the following dates:

(a) Successful completion of the Department’s final construction inspection; or

(b) The date construction activities were substantially completed, as determined by the Department when:

(1) The Department did not require a final construction inspection;

(2) The major regulated project failed a final construction inspection; or

(3) The person failed to schedule a final construction inspection at the required time.

527.4 No person shall be out of compliance with a portion of their Offv requirement for any period of time.

527.5 To comply with one (1) gallon of an Offv requirement for one (1) year, a person shall use one (1) High-Impact Stormwater Retention Credit (High-Impact SRC) unless they:

(a) Are allowed to substitute a:

(1) Purchased Low-Impact Stormwater Retention Credit (Low-Impact SRC) pursuant to §§ 527.9 and 527.10; or

(2) Self-generated Low-Impact SRC pursuant to § 527.12;

(b) Are required to use one and one-quarter (1.25) Stormwater Retention Credits (SRCs) for an Anacostia Waterfront Development Zone site (AWDZ site) pursuant to § 527.7; or

(c) Pay the in-lieu fee for the gallon of Offv, unless prohibited by § 527.8.

527.6 No person shall use SRCs to comply with an Offv requirement without obtaining the Department’s approval.

527.7 For an AWDZ site, a person shall use one and one-quarter (1.25) SRCs to comply with one (1) gallon of an Offv requirement if the SRCs are certified for retention capacity located outside of the Anacostia watershed.

527.8 To comply with an Offv requirement, a person shall use only High-Impact SRCs if the project with Offv received Department approval for:

(a) Permanent Offv compliance pursuant to §§ 527.20–527.24; or

(b) A waiver:

(1) For two (2) year storm detention requirements pursuant to § 520.2(a); or

(2) To retain less than fifty percent (50%) of the Stormwater Retention Volume (SWRv) on-site in the Gray Combined Sewer System (Gray CSS) area pursuant to §§ 520.4(a)(2) or 522.5(a)(2), unless the substitution is a Low-Impact Voluntary SRC.

527.9 A person who purchases SRCs to comply with an Offv requirement and who is not otherwise prohibited by § 527.8 may substitute High-Impact SRCs with:

(a) Low-Impact Municipal Separate Storm Sewer System (MS4) SRCs when:

(1) High-Impact SRCs are not available pursuant to § 527.10; or

(2) The site with Offv is an AWDZ site and High-Impact SRCs certified for retention capacity located in the Anacostia watershed are not available pursuant to § 527.10;

(b) Low-Impact Green Combined Sewer System (Green CSS) SRCs when:

(1) High-Impact SRCs and Low-Impact MS4 SRCs are not available

pursuant to § 527.10; and

(2) The site with the Offv requirement:

(A) Drains to the Green CSS area or the Gray CSS area;

(B) Is not an AWDZ site; and

(C) Is located outside the limits of the existing Public Right-of-Way (PROW); or

(c) Low-Impact Gray CSS SRCs when:

(1) High-Impact SRCs and Low-Impact MS4 SRCs are not available pursuant to § 527.10; and

(2) The site with the Offv requirement:

(A) Drains to the Gray CSS area;

(B) Is not an AWDZ site; and

(C) Is located outside the limits of the existing PROW.

527.10 A type of SRC required in § 527.9 is not available for purchase if on the Offv compliance date there are not enough SRCs of that type for sale to comply with the site's Offv requirement for one (1) year.

527.11 When purchasing SRCs pursuant to §§ 527.9 and 527.10, a person may use Low-Impact SRCs to comply with the Offv requirement for only the next single year.

527.12 A person who uses self-generated SRCs to comply with an Offv requirement and who is not otherwise prohibited by § 527.8 shall use SRCs as follows:

(a) For an AWDZ site; a site that drains to the MS4 area; or any PROW site that drains to the CSS and achieves less than fifty percent (50%) of the SWRv requirement on-site, a person shall use any of the following:

(1) Self-generated High-Impact SRCs; or

(2) Self-generated Low-Impact MS4 SRCs;

(b) For a site that drains to the Green CSS area, a person shall use any of the following:

(1) Self-generated High-Impact SRCs;

(2) Self-generated Low-Impact MS4 SRCs; or

(3) Self-generated Low-Impact Green CSS SRCs; and

(c) For a site that drains to the Gray CSS area and achieves:

(1) Fifty percent (50%) or more of the SWRv requirement on-site, a person may use any self-generated SRCs; or

(2) Less than fifty percent (50%) of the SWRv requirement on-site, a person shall use any of the following:

(A) Self-generated High-Impact SRCs;

(B) Self-generated Low-Impact Voluntary SRCs; or

(C) If the Department approves an application for relief from extraordinarily difficult site conditions, then any self-generated SRCs.

527.13 Only the current owner of an SRC or their agent may apply to the Department for approval to use that SRC to comply with one (1) gallon of an Offv requirement.

527.14 To comply with an Offv requirement, the property owner or their agent shall provide the following to the Department before the Offv compliance date:

(a) For use of SRCs, a completed application in the Department's submittal database that includes:

(1) The unique serial numbers of the SRCs; and

(2) Information about the site with Offv that will use the SRCs, including property location and stormwater management on the property; or

(b) For use of an in-lieu fee payment:

(1) A completed form in the Department's submittal database to notify the Department of the intent to use an in-lieu fee payment; and

(2) Payment of the in-lieu fee.

527.15 The Department shall not approve an application to use an SRC to comply with an Offv requirement if the lifespan of the SRC has terminated pursuant to § 532.527.16 The one (1) year lifespan of an SRC or an in-lieu fee payment begins on the date it is used to comply with one (1) gallon of an Offv requirement.527.17 If the Department determines that a property owner failed to comply with an Offv requirement, the Department shall:- (a) Provide the property owner with written notice of noncompliance; and

- (b) Require the property owner to:

- (1) Pay the in-lieu fee for each gallon of Offv; and

- (2) Pay an administrative late fee calculated as ten percent (10%) of the in-lieu fee amount pursuant to § 501.12.527.18 A property owner who receives a notice of noncompliance for an Offv requirement shall:- (a) Comply; and

- (b) Pay the assessed fees.527.19 If a property owner fails to comply within thirty (30) days after the date the Department issued a notice of noncompliance with an Offv requirement, the Department shall administratively use the property owner's eligible unused SRCs to comply with the Offv requirement.527.20 A requirement to comply with a gallon of Offv shall terminate when a property owner has complied with all prior years of the Offv requirement and the performance requirements of this chapter, and:- (a) Retained the gallon on-site in compliance with a Department-approved Stormwater Management Plan (SWMP) revision;

- (b) Redeveloped the site in compliance with a new Department-approved SWMP; or

- (c) If the major regulated project with the Offv requirement is located in the Gray CSS area, used High-Impact SRCs to comply with the Offv for thirty (30) consecutive compliance years pursuant to § 527.21.

527.21 Pursuant to § 527.20(c), the Department will terminate an Offv requirement for a project located in the Gray CSS area provided that:- (a) The property owner shall comply with thirty (30) consecutive years of the Offv requirement solely by using High-Impact SRCs;

- (b) The property owner or their agent shall, using a form in the Department's submittal database, apply to the Department to request the permanent Offv compliance option within three (3) years of the later of:

- (c)

- (1) (The effective date of the final rulemaking); or

- (2) The date construction was substantially completed, as determined by the Department;

- (d) If the property owner has already complied with one (1) or more years of the Offv requirement pursuant to § 527.21(a), the Department will count these years of compliance toward the thirty (30) year compliance period;

- (e) The application to request permanent Offv compliance shall include:

- (1) The plan number for the Offv requirement;

- (2) The start and end dates of the thirty (30) year compliance period;

- (3) Enough High-Impact SRCs to comply with at least the next four (4) years of the Offv requirement; and

- (4) Evidence that within four (4) years after the application date, the property owner will provide to the Department the remaining High-Impact SRCs to comply with a total of thirty (30) years of the Offv requirement. The evidence shall consist of either:

- (A) An executed contract between the property owner and an SRC seller; or

- (B) A promise signed by the property owner;

- (f) Within four (4) years after the date of the application, the property owner shall provide the Department the full amount of High-Impact SRCs required to comply with thirty (30) years of the Offv requirement;

(g) The High-Impact SRCs a person uses pursuant to §§ 527.20 and 527.21:

(1) Shall not be applied or transferred in full or in part to the Offv requirement for a different plan; and

(2) Are not refundable in full or in part even if any portion of the site is redeveloped before the end of the thirty (30) year compliance period; and

(h) The Department will provide the property owner written confirmation when the property owner has:

(1) Complied with thirty (30) years of the Offv requirement and the Offv requirement is terminated; or

(2) Not completed the application requirements and the application for permanent Offv compliance is revoked.

527.22 A property owner may request to terminate an Offv requirement pursuant to § 517.7 for installation or replacement of athletic playing fields, permeable athletic tracks, or permeable playground surfaces or suspend the Offv pursuant to § 518.14 for single-family or two-family houses constructed as affordable housing, if they:

(a) Maintain each on-site Best Management Practice (BMP) pursuant to the approved SWMP for the project; and

(b) Submit a request through the Department's submittal database and attach a letter explaining why the project qualifies for Offv termination or suspension.

527.23 If the Department approves a request to terminate or suspend an Offv requirement pursuant to §§ 517.7 or 518.14:

(a) The applicant shall revise the declaration of covenants, if necessary, pursuant to § 529.4; and

(b) The Department shall prorate and refund any excess amount of SRCs or in-lieu fee payment used to comply with the Offv requirement beyond the termination or suspension date.

527.24 The Department shall prorate and refund SRCs or an in-lieu fee payment that an owner used to comply with an Offv requirement if:

(a) The Department determines that the Offv requirement terminated before the end of the compliance period; or

(b) The applicant had previously paid the in-lieu fee to the Department to comply with the Offv requirement and subsequently provided SRCs to the Department for the Offv.

SOURCE: Final Rulemaking published at 35 DCR 21 (January 1, 1988); as amended by Final Rulemaking published at 60 DCR 10640 (July 19, 2013); as amended by Final Rulemaking published at 67 DCR 818 (January 31, 2020); as amended by Final Rulemaking published at 72 DCR 012101 (October 31, 2025).