Index: Ringtoets/HydraRing/src/Ringtoets.HydraRing.IO/HydraulicLocationConfigurationDatabase/HydraulicLocationConfigurationDatabaseReader.cs
===================================================================
diff -u -r87c8cbe523ecd4a197993251f0cf80b521cc3c20 -rff28b61980b68b15722adaf34f3c71321dd1b47e
--- Ringtoets/HydraRing/src/Ringtoets.HydraRing.IO/HydraulicLocationConfigurationDatabase/HydraulicLocationConfigurationDatabaseReader.cs	(.../HydraulicLocationConfigurationDatabaseReader.cs)	(revision 87c8cbe523ecd4a197993251f0cf80b521cc3c20)
+++ Ringtoets/HydraRing/src/Ringtoets.HydraRing.IO/HydraulicLocationConfigurationDatabase/HydraulicLocationConfigurationDatabaseReader.cs	(.../HydraulicLocationConfigurationDatabaseReader.cs)	(revision ff28b61980b68b15722adaf34f3c71321dd1b47e)
@@ -67,7 +67,7 @@
         /// Gets the location ids from the database, based upon <paramref name="trackId"/>.
         /// </summary>
         /// <param name="trackId">The hydraulic boundary track id.</param>
-        /// <returns>A dictionary with pairs of Hrd location id (key) and location id (value) as found in the database.</returns>
+        /// <returns>A collection of <see cref="ReadHydraulicLocationMapping"/> as found in the database.</returns>
         /// <exception cref="CriticalFileReadException">Thrown when the database query failed.</exception>
         /// <exception cref="LineParseException">Thrown when the database returned incorrect values for 
         /// required properties.</exception>
@@ -100,14 +100,15 @@
         /// Gets the location ids from the database, based upon <paramref name="trackParameter"/>.
         /// </summary>
         /// <param name="trackParameter">A parameter containing the hydraulic boundary track id.</param>
-        /// <returns>A dictionary with pairs of Hrd location id (key) and location id (value) as found in the database.</returns>
+        /// <returns>A collection of <see cref="ReadHydraulicLocationMapping"/> as found in the database.</returns>
         /// <exception cref="SQLiteException">Thrown when the database query failed.</exception>
         /// <exception cref="InvalidCastException">Thrown when the database returned incorrect values for 
         /// required properties.</exception>
         private IEnumerable<ReadHydraulicLocationMapping> GetLocationIdsFromDatabase(SQLiteParameter trackParameter)
         {
-            var mappings = new List<ReadHydraulicLocationMapping>();
             string query = HydraulicLocationConfigurationDatabaseQueryBuilder.GetLocationIdsByTrackIdQuery();
+            var locationLookup = new Dictionary<long, long>();
+
             using (IDataReader dataReader = CreateDataReader(query, trackParameter))
             {
                 while (MoveNext(dataReader))
@@ -116,18 +117,18 @@
                     long hlcdLocationId = Convert.ToInt64(dataReader[LocationsTableDefinitions.LocationId]);
 
                     // Must be unique
-                    if (mappings.Any(m => m.HrdLocationId == hrdLocationId))
+                    if (locationLookup.ContainsKey(hrdLocationId))
                     {
                         log.Warn(Resources.HydraulicLocationConfigurationDatabaseReader_GetLocationIdFromDatabase_Ambiguous_Row_Found_Take_First);
                     }
                     else
                     {
-                        mappings.Add(new ReadHydraulicLocationMapping(hrdLocationId, hlcdLocationId));
+                        locationLookup[hrdLocationId] = hlcdLocationId;
                     }
                 }
             }
 
-            return mappings;
+            return locationLookup.Select(lookup => new ReadHydraulicLocationMapping(lookup.Key, lookup.Value)).ToArray();
         }
     }
 }
\ No newline at end of file
Index: Ringtoets/HydraRing/src/Ringtoets.HydraRing.IO/HydraulicLocationConfigurationDatabase/ReadHydraulicLocationMapping.cs
===================================================================
diff -u -r4bb3d8d1b4b5e3a303294163f0218e3176caeb85 -rff28b61980b68b15722adaf34f3c71321dd1b47e
--- Ringtoets/HydraRing/src/Ringtoets.HydraRing.IO/HydraulicLocationConfigurationDatabase/ReadHydraulicLocationMapping.cs	(.../ReadHydraulicLocationMapping.cs)	(revision 4bb3d8d1b4b5e3a303294163f0218e3176caeb85)
+++ Ringtoets/HydraRing/src/Ringtoets.HydraRing.IO/HydraulicLocationConfigurationDatabase/ReadHydraulicLocationMapping.cs	(.../ReadHydraulicLocationMapping.cs)	(revision ff28b61980b68b15722adaf34f3c71321dd1b47e)
@@ -22,7 +22,7 @@
 namespace Ringtoets.HydraRing.IO.HydraulicLocationConfigurationDatabase
 {
     /// <summary>
-    /// Class for holding location mapping data that is read from a hydraulic location configuration database file.
+    /// Class for holding a mapping between the hydraulic boundary location id and hydraulic location configuration id.
     /// </summary>
     public class ReadHydraulicLocationMapping
     {