diff --git a/backend/src/routes/properties.js b/backend/src/routes/properties.js
index 5e1f168..b0fa6d2 100644
--- a/backend/src/routes/properties.js
+++ b/backend/src/routes/properties.js
@@ -308,7 +308,7 @@ router.delete('/:id', validateParams(idParamSchema), async (req, res, next) => {
       throw new AppError('Property not found', 404);
     }
 
-    // Check for active applications
+    // Check for active applications (planned/in_progress) linked to any sections on this property
     const activeApps = await pool.query(
       `SELECT COUNT(*) as count 
        FROM application_plans ap
@@ -322,6 +322,18 @@ router.delete('/:id', validateParams(idParamSchema), async (req, res, next) => {
       throw new AppError('Cannot delete property with active applications', 400);
     }
 
+    // Prevent deletion if there are historical application logs referencing sections on this property
+    const histLogs = await pool.query(
+      `SELECT COUNT(*) as count
+       FROM application_logs al
+       JOIN lawn_sections ls ON al.lawn_section_id = ls.id
+       WHERE ls.property_id = $1`,
+      [propertyId]
+    );
+    if (parseInt(histLogs.rows[0].count) > 0) {
+      throw new AppError('Cannot delete property with historical application logs; delete logs first or archive data', 400);
+    }
+
     await pool.query('DELETE FROM properties WHERE id = $1', [propertyId]);
 
     res.json({
@@ -505,7 +517,7 @@ router.delete('/:propertyId/sections/:sectionId', async (req, res, next) => {
       throw new AppError('Lawn section not found', 404);
     }
 
-    // Check for active applications
+    // Check for active applications that include this section
     const activeApps = await pool.query(
       `SELECT COUNT(*) as count 
        FROM application_plans ap
@@ -518,6 +530,15 @@ router.delete('/:propertyId/sections/:sectionId', async (req, res, next) => {
       throw new AppError('Cannot delete section with active applications', 400);
     }
 
+    // Prevent deletion if there are historical logs tied to this section
+    const logs = await pool.query(
+      `SELECT COUNT(*) as count FROM application_logs WHERE lawn_section_id = $1`,
+      [sectionId]
+    );
+    if (parseInt(logs.rows[0].count) > 0) {
+      throw new AppError('Cannot delete section with historical application logs; delete logs first', 400);
+    }
+
     await pool.query('DELETE FROM lawn_sections WHERE id = $1', [sectionId]);
 
     res.json({