Index: Ringtoets/Common/src/Ringtoets.Common.Data/AssessmentSection/AssessmentSectionExtensions.cs
===================================================================
diff -u -r83ad808e24b4781346cbf61955354127fd942a75 -rf34577f6da915277f5098f362150d006aea972b7
--- Ringtoets/Common/src/Ringtoets.Common.Data/AssessmentSection/AssessmentSectionExtensions.cs	(.../AssessmentSectionExtensions.cs)	(revision 83ad808e24b4781346cbf61955354127fd942a75)
+++ Ringtoets/Common/src/Ringtoets.Common.Data/AssessmentSection/AssessmentSectionExtensions.cs	(.../AssessmentSectionExtensions.cs)	(revision f34577f6da915277f5098f362150d006aea972b7)
@@ -21,8 +21,6 @@
 
 using System;
 using System.ComponentModel;
-using System.Linq;
-using Core.Common.Base;
 using Core.Common.Base.Data;
 using Ringtoets.Common.Data.Contribution;
 using Ringtoets.Common.Data.Hydraulics;
@@ -35,17 +33,15 @@
     public static class AssessmentSectionExtensions
     {
         /// <summary>
-        /// Gets the normative assessment level for a <see cref="HydraulicBoundaryLocation"/>.
+        /// Gets the normative assessment level from a <see cref="HydraulicBoundaryLocation"/>.
         /// </summary>
-        /// <param name="assessmentSection">The assessment section to get the normative assessment
-        /// level from.</param>
+        /// <param name="assessmentSection">The assessment section.</param>
         /// <param name="hydraulicBoundaryLocation">The hydraulic boundary location to get the normative
-        /// assessment level for.</param>
+        /// assessment level from.</param>
         /// <returns>The normative assessment level or <see cref="RoundedDouble.NaN"/> when:
         /// <list type="bullet">
         /// <item><paramref name="hydraulicBoundaryLocation"/> is <c>null</c>;</item>
-        /// <item><paramref name="hydraulicBoundaryLocation"/> is not part of <paramref name="assessmentSection"/>.</item>
-        /// <item><paramref name="assessmentSection"/> contains no corresponding calculation output.</item>
+        /// <item><paramref name="hydraulicBoundaryLocation"/> contains no corresponding calculation output.</item>
         /// </list>
         /// </returns>
         /// <exception cref="ArgumentNullException">Thrown when <paramref name="assessmentSection"/>
@@ -70,23 +66,15 @@
                                                        typeof(NormType));
             }
 
-            IObservableEnumerable<HydraulicBoundaryLocationCalculation> calculations;
-
             switch (normType)
             {
                 case NormType.Signaling:
-                    calculations = assessmentSection.WaterLevelCalculationsForSignalingNorm;
-                    break;
+                    return hydraulicBoundaryLocation?.DesignWaterLevelCalculation2.Output?.Result ?? RoundedDouble.NaN;
                 case NormType.LowerLimit:
-                    calculations = assessmentSection.WaterLevelCalculationsForLowerLimitNorm;
-                    break;
+                    return hydraulicBoundaryLocation?.DesignWaterLevelCalculation3.Output?.Result ?? RoundedDouble.NaN;
                 default:
                     throw new NotSupportedException();
             }
-
-            HydraulicBoundaryLocationCalculation calculation = calculations.FirstOrDefault(calc => ReferenceEquals(calc.HydraulicBoundaryLocation, hydraulicBoundaryLocation));
-
-            return calculation?.Output?.Result ?? RoundedDouble.NaN;
         }
     }
 }
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