Chesapeake Bay Critical Area Program — IDA / LDA / RCA Overlay (MD)
Tracked preemption from the Maryland overlay bundle.
Overview
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Effective
1984-06-01
Sunset
—
Authority
state
Scope
state:MD
Other Maryland preemptions
Maryland Land Use Article — Zoning & Planning Enabling AuthorityMaryland Historic District Enabling Authority (LU §8-201)Maryland Military Installation Joint Land Use Studies (LU §22-301)Atlantic Coastal Bays Critical Area — Worcester County OverlayMaryland Priority Funding Areas (PFA) — Smart Growth ActMaryland Rural Legacy Program — Designated Rural Legacy AreasMaryland Forest Conservation Act (FCA)Maryland Wetlands of Special State Concern (WSSC) & Nontidal Wetlands
Trigger predicate
When this evaluates true for a parcel, the law's preempted fields take precedence over base zoning.
OR
city.is_in_chesapeake_critical_area==Trueparcel.in_critical_area_1000ft_buffer==Trueparcel.geometrygeographic match
Preempted fields
5 fields on the base district schema are rewritten when the trigger fires.
| Field | Op | Value | Note |
|---|---|---|---|
base_districts[*].max_units_per_acre | cap_at | 0.05 | Resource Conservation Area cap: 1 unit per 20 acres maximum density (0.05 du/ac), regardless of underlying local zoning. NR §8-1808.1 / COMAR 27.01.02. |
base_districts[*].max_units_per_acre | cap_at | 4 | Limited Development Area cap: 4 units per acre maximum density. NR §8-1808.1 / COMAR 27.01.02. |
base_districts[*].impervious_cover_pct | cap_at | 15 | 15% impervious-cover cap on LDA / RCA parcels; IDA parcels exceeding 15% require offsetting surface-runoff mitigation (10% pollutant reduction rule). |
base_districts[*].riparian_buffer_ft | floor_at | 100 | 100-foot minimum Buffer from tidal waters, tidal wetlands, and tributary streams; expanded to 200 ft on steep slopes and within some RCA programs. Development, impervious surface, and clearing largely prohibited within the Buffer. |
review_type | override | critical_area_commission_approved_local_program_required | Each jurisdiction in the critical area must adopt a Critical Area Program approved by the state Critical Area Commission (CAC); CAC may disapprove local program amendments (functional preemption). HEAA §7-501 et seq. density floors yield to RCA / LDA caps where in conflict. |
Citation
Authority source
Md. Code Ann., Natural Resources §§8-1801 through 8-1817 (Chesapeake and Atlantic Coastal Bays Critical Area Protection Program); COMAR Title 27 (Critical Area Commission regulations)
§ §§8-1801 through 8-1817
Research notes
Geographic reach: all land within 1,000 feet of Mean High Water Line (or landward edge of tidal wetlands) of the Chesapeake Bay, Atlantic Coastal Bays, or tidal tributaries. Touches all or part of 16 counties + Baltimore City + 44 municipalities including Anne Arundel, Baltimore County, Baltimore City, Calvert, Caroline, Cecil, Charles, Dorchester, Harford, Kent, Prince George's (small), Queen Anne's, St. Mary's, Somerset, Talbot, Wicomico, Worcester. Three mandatory land-classification zones: IDA (Intensely Developed), LDA (Limited Development, ≤4 du/ac), RCA (Resource Conservation, ≤1 du/20 ac). Each county receives a limited 'growth allocation' for RCA→LDA or LDA→IDA reclassification; once spent, intensification requires CAC program amendment. 2026 amendments (HB 258/SB 178, HB 247) pending codification redefine 'adjacent,' extend CAC review timelines, and modify county variance authority. Administered by Critical Area Commission, DNR.