diff --git a/backend/alembic/versions/202607160001_vector_feature_municipality_index.py b/backend/alembic/versions/202607160001_vector_feature_municipality_index.py
new file mode 100644
index 00000000..8fda27f1
--- /dev/null
+++ b/backend/alembic/versions/202607160001_vector_feature_municipality_index.py
@@ -0,0 +1,22 @@
+"""Index partitioned vector features by dataset and municipality."""
+
+from alembic import op
+import sqlalchemy as sa
+
+
+revision = "202607160001"
+down_revision = "202607150001"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.create_index(
+        "ix_vector_features_dataset_municipality",
+        "vector_features",
+        ["dataset_id", sa.text("(properties_json ->> 'municipality')")],
+    )
+
+
+def downgrade() -> None:
+    op.drop_index("ix_vector_features_dataset_municipality", table_name="vector_features")
diff --git a/backend/app/models/entities.py b/backend/app/models/entities.py
index 72395040..9ec05743 100644
--- a/backend/app/models/entities.py
+++ b/backend/app/models/entities.py
@@ -4,7 +4,7 @@ import uuid
 from datetime import datetime
 
 from geoalchemy2 import Geometry
-from sqlalchemy import CheckConstraint, DateTime, ForeignKey, Float, Index, JSON, String, Text, UniqueConstraint, func
+from sqlalchemy import CheckConstraint, DateTime, ForeignKey, Float, Index, JSON, String, Text, UniqueConstraint, func, text
 from sqlalchemy.sql.sqltypes import Integer
 from sqlalchemy.dialects.postgresql import UUID
 from sqlalchemy.orm import Mapped, mapped_column, relationship
@@ -140,6 +140,11 @@ class VectorFeature(Base):
         Index("ix_vector_features_dataset_id", "dataset_id"),
         Index("ix_vector_features_geometry", "geometry", postgresql_using="gist"),
         Index("ix_vector_features_dataset_source_feature", "dataset_id", "source_feature_id"),
+        Index(
+            "ix_vector_features_dataset_municipality",
+            "dataset_id",
+            text("(properties_json ->> 'municipality')"),
+        ),
     )
 
     id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
diff --git a/backend/tests/test_sprint210_regional_bwk_natura2000.py b/backend/tests/test_sprint210_regional_bwk_natura2000.py
index 8d88172f..8fc50e5c 100644
--- a/backend/tests/test_sprint210_regional_bwk_natura2000.py
+++ b/backend/tests/test_sprint210_regional_bwk_natura2000.py
@@ -237,12 +237,19 @@ def test_regional_operator_is_packaged_release_checked_and_exact_area_is_preferr
     service = (ROOT / "backend/app/services/vector_feature_service.py").read_text(encoding="utf-8")
     workspace = (ROOT / "frontend/src/components/map/MapWorkspace.tsx").read_text(encoding="utf-8")
     catalog = (ROOT / "frontend/src/components/datasets/SourceCatalogPanel.tsx").read_text(encoding="utf-8")
+    model = (ROOT / "backend/app/models/entities.py").read_text(encoding="utf-8")
+    migration = (
+        ROOT / "backend/alembic/versions/202607160001_vector_feature_municipality_index.py"
+    ).read_text(encoding="utf-8")
 
     assert "COPY scripts/provision_regional_bwk_natura2000.py" in dockerfile
     assert "py_compile scripts/provision_regional_bwk_natura2000.py" in readiness
     assert '"provision_regional_bwk_natura2000.py"' in service
     assert "dataset.area_id === selectedAreaId ? 10_000_000" in workspace
     assert "largestBwkSnapshot" in catalog
+    assert "ix_vector_features_dataset_municipality" in model
+    assert "ix_vector_features_dataset_municipality" in migration
+    assert 'down_revision = "202607150001"' in migration
 
 
 def test_regional_bwk_uses_only_canonical_preclipped_municipality_partitions() -> None:
diff --git a/docs/DATABASE_IMPLEMENTATION_PLAN.md b/docs/DATABASE_IMPLEMENTATION_PLAN.md
index 2d585a5a..e5da1089 100644
--- a/docs/DATABASE_IMPLEMENTATION_PLAN.md
+++ b/docs/DATABASE_IMPLEMENTATION_PLAN.md
@@ -306,3 +306,12 @@ Their `provenance_metadata` records 28-partition identity, combined output
 checksum and retained raw-response status. Municipality-clipped source ids are
 partition-suffixed for uniqueness, while `identity_stable=false` prohibits
 object-lineage interpretation. No partition or temporal shadow table is added.
+### Partitioned vector feature lookup index
+
+Regional operator Datasets retain their municipality partition identity in
+`vector_features.properties_json.municipality`. Migration `202607160001` adds
+the composite expression index
+`ix_vector_features_dataset_municipality(dataset_id, properties_json->>'municipality')`.
+It supports exact preclipped municipality selection without changing the
+canonical `vector_features` schema or introducing operator-specific tables.
+Free rectangle queries continue to use the geometry GiST index.