Index: Ringtoets/Integration/src/Ringtoets.Integration.Forms/Views/DesignWaterLevelCalculationsView.cs
===================================================================
diff -u -rceea3576d68a9ec132886da026446b28672414b7 -r82189953ee9562a0cb73686eef4783764c153e31
--- Ringtoets/Integration/src/Ringtoets.Integration.Forms/Views/DesignWaterLevelCalculationsView.cs	(.../DesignWaterLevelCalculationsView.cs)	(revision ceea3576d68a9ec132886da026446b28672414b7)
+++ Ringtoets/Integration/src/Ringtoets.Integration.Forms/Views/DesignWaterLevelCalculationsView.cs	(.../DesignWaterLevelCalculationsView.cs)	(revision 82189953ee9562a0cb73686eef4783764c153e31)
@@ -50,7 +50,7 @@
         /// <exception cref="ArgumentNullException">Thrown when <paramref name="calculations"/>, <paramref name="assessmentSection"/>
         /// or <paramref name="getNormFunc"/> is <c>null</c>.</exception>
         /// <exception cref="ArgumentException">Thrown when <paramref name="categoryBoundaryName"/> is <c>null</c> or empty.</exception>
-        public DesignWaterLevelCalculationsView(ObservableList<HydraulicBoundaryLocationCalculation> calculations,
+        public DesignWaterLevelCalculationsView(IObservableEnumerable<HydraulicBoundaryLocationCalculation> calculations,
                                                 IAssessmentSection assessmentSection,
                                                 Func<double> getNormFunc,
                                                 string categoryBoundaryName)
Index: Ringtoets/Integration/src/Ringtoets.Integration.Forms/Views/WaveHeightCalculationsView.cs
===================================================================
diff -u -rceea3576d68a9ec132886da026446b28672414b7 -r82189953ee9562a0cb73686eef4783764c153e31
--- Ringtoets/Integration/src/Ringtoets.Integration.Forms/Views/WaveHeightCalculationsView.cs	(.../WaveHeightCalculationsView.cs)	(revision ceea3576d68a9ec132886da026446b28672414b7)
+++ Ringtoets/Integration/src/Ringtoets.Integration.Forms/Views/WaveHeightCalculationsView.cs	(.../WaveHeightCalculationsView.cs)	(revision 82189953ee9562a0cb73686eef4783764c153e31)
@@ -50,7 +50,7 @@
         /// <exception cref="ArgumentNullException">Thrown when <paramref name="calculations"/>, <paramref name="assessmentSection"/>
         /// or <paramref name="getNormFunc"/> is <c>null</c>.</exception>
         /// <exception cref="ArgumentException">Thrown when <paramref name="categoryBoundaryName"/> is <c>null</c> or empty.</exception>
-        public WaveHeightCalculationsView(ObservableList<HydraulicBoundaryLocationCalculation> calculations,
+        public WaveHeightCalculationsView(IObservableEnumerable<HydraulicBoundaryLocationCalculation> calculations,
                                           IAssessmentSection assessmentSection,
                                           Func<double> getNormFunc,
                                           string categoryBoundaryName)
Index: Ringtoets/Integration/test/Ringtoets.Integration.Forms.Test/Views/DesignWaterLevelCalculationsViewTest.cs
===================================================================
diff -u -r8560f7a7b53b45ad9d2d4afc6172ffdd05342082 -r82189953ee9562a0cb73686eef4783764c153e31
--- Ringtoets/Integration/test/Ringtoets.Integration.Forms.Test/Views/DesignWaterLevelCalculationsViewTest.cs	(.../DesignWaterLevelCalculationsViewTest.cs)	(revision 8560f7a7b53b45ad9d2d4afc6172ffdd05342082)
+++ Ringtoets/Integration/test/Ringtoets.Integration.Forms.Test/Views/DesignWaterLevelCalculationsViewTest.cs	(.../DesignWaterLevelCalculationsViewTest.cs)	(revision 82189953ee9562a0cb73686eef4783764c153e31)
@@ -242,7 +242,7 @@
         public void DesignWaterLevelCalculationsView_CalculationUpdated_DataGridViewCorrectlyUpdated()
         {
             // Setup
-            ObservableList<HydraulicBoundaryLocationCalculation> hydraulicBoundaryLocationCalculations = GetTestHydraulicBoundaryLocationCalculations();
+            IObservableEnumerable<HydraulicBoundaryLocationCalculation> hydraulicBoundaryLocationCalculations = GetTestHydraulicBoundaryLocationCalculations();
 
             ShowFullyConfiguredDesignWaterLevelCalculationsView(hydraulicBoundaryLocationCalculations, testForm);
 
@@ -267,7 +267,7 @@
         public void DesignWaterLevelCalculationsView_CalculationUpdated_IllustrationPointsControlCorrectlyUpdated()
         {
             // Setup
-            ObservableList<HydraulicBoundaryLocationCalculation> hydraulicBoundaryLocationCalculations = GetTestHydraulicBoundaryLocationCalculations();
+            IObservableEnumerable<HydraulicBoundaryLocationCalculation> hydraulicBoundaryLocationCalculations = GetTestHydraulicBoundaryLocationCalculations();
 
             ShowFullyConfiguredDesignWaterLevelCalculationsView(hydraulicBoundaryLocationCalculations, testForm);
 
@@ -289,7 +289,7 @@
             var output = new TestHydraulicBoundaryLocationOutput(generalResult);
 
             // Call
-            HydraulicBoundaryLocationCalculation boundaryLocationCalculation = hydraulicBoundaryLocationCalculations[2];
+            HydraulicBoundaryLocationCalculation boundaryLocationCalculation = hydraulicBoundaryLocationCalculations.ElementAt(2);
             boundaryLocationCalculation.Output = output;
             boundaryLocationCalculation.NotifyObservers();
 
@@ -302,7 +302,7 @@
         public void CalculateForSelectedButton_OneSelected_CallsCalculateDesignWaterLevels()
         {
             // Setup
-            ObservableList<HydraulicBoundaryLocationCalculation> hydraulicBoundaryLocationCalculations = GetTestHydraulicBoundaryLocationCalculations();
+            IObservableEnumerable<HydraulicBoundaryLocationCalculation> hydraulicBoundaryLocationCalculations = GetTestHydraulicBoundaryLocationCalculations();
 
             DesignWaterLevelCalculationsView view = ShowFullyConfiguredDesignWaterLevelCalculationsView(hydraulicBoundaryLocationCalculations, testForm);
 
@@ -386,7 +386,7 @@
 
             mockRepository.ReplayAll();
 
-            ObservableList<HydraulicBoundaryLocationCalculation> hydraulicBoundaryLocationCalculations = GetTestHydraulicBoundaryLocationCalculations();
+            IObservableEnumerable<HydraulicBoundaryLocationCalculation> hydraulicBoundaryLocationCalculations = GetTestHydraulicBoundaryLocationCalculations();
 
             DesignWaterLevelCalculationsView view = ShowDesignWaterLevelCalculationsView(hydraulicBoundaryLocationCalculations,
                                                                                          assessmentSection,
@@ -458,7 +458,7 @@
 
             mockRepository.ReplayAll();
 
-            ObservableList<HydraulicBoundaryLocationCalculation> hydraulicBoundaryLocationCalculations = GetTestHydraulicBoundaryLocationCalculations();
+            IObservableEnumerable<HydraulicBoundaryLocationCalculation> hydraulicBoundaryLocationCalculations = GetTestHydraulicBoundaryLocationCalculations();
 
             DesignWaterLevelCalculationsView view = ShowDesignWaterLevelCalculationsView(hydraulicBoundaryLocationCalculations,
                                                                                          assessmentSection,
@@ -529,7 +529,7 @@
 
             mockRepository.ReplayAll();
 
-            ObservableList<HydraulicBoundaryLocationCalculation> hydraulicBoundaryLocationCalculations = GetTestHydraulicBoundaryLocationCalculations();
+            IObservableEnumerable<HydraulicBoundaryLocationCalculation> hydraulicBoundaryLocationCalculations = GetTestHydraulicBoundaryLocationCalculations();
 
             DesignWaterLevelCalculationsView view = ShowDesignWaterLevelCalculationsView(hydraulicBoundaryLocationCalculations,
                                                                                          assessmentSection,
@@ -588,7 +588,7 @@
                                 });
         }
 
-        private static DesignWaterLevelCalculationsView ShowDesignWaterLevelCalculationsView(ObservableList<HydraulicBoundaryLocationCalculation> calculations,
+        private static DesignWaterLevelCalculationsView ShowDesignWaterLevelCalculationsView(IObservableEnumerable<HydraulicBoundaryLocationCalculation> calculations,
                                                                                              IAssessmentSection assessmentSection,
                                                                                              double norm,
                                                                                              string categoryBoundaryName,
@@ -605,7 +605,7 @@
             return view;
         }
 
-        private static DesignWaterLevelCalculationsView ShowFullyConfiguredDesignWaterLevelCalculationsView(ObservableList<HydraulicBoundaryLocationCalculation> calculations,
+        private static DesignWaterLevelCalculationsView ShowFullyConfiguredDesignWaterLevelCalculationsView(IObservableEnumerable<HydraulicBoundaryLocationCalculation> calculations,
                                                                                                             Form form)
         {
             var assessmentSection = new ObservableTestAssessmentSectionStub();
Index: Ringtoets/Integration/test/Ringtoets.Integration.Forms.Test/Views/WaveHeightCalculationsViewTest.cs
===================================================================
diff -u -r8560f7a7b53b45ad9d2d4afc6172ffdd05342082 -r82189953ee9562a0cb73686eef4783764c153e31
--- Ringtoets/Integration/test/Ringtoets.Integration.Forms.Test/Views/WaveHeightCalculationsViewTest.cs	(.../WaveHeightCalculationsViewTest.cs)	(revision 8560f7a7b53b45ad9d2d4afc6172ffdd05342082)
+++ Ringtoets/Integration/test/Ringtoets.Integration.Forms.Test/Views/WaveHeightCalculationsViewTest.cs	(.../WaveHeightCalculationsViewTest.cs)	(revision 82189953ee9562a0cb73686eef4783764c153e31)
@@ -242,7 +242,7 @@
         public void WaveHeightCalculationsView_CalculationUpdated_DataGridViewCorrectlyUpdated()
         {
             // Setup
-            ObservableList<HydraulicBoundaryLocationCalculation> hydraulicBoundaryLocationCalculations = GetTestHydraulicBoundaryLocationCalculations();
+            IObservableEnumerable<HydraulicBoundaryLocationCalculation> hydraulicBoundaryLocationCalculations = GetTestHydraulicBoundaryLocationCalculations();
 
             ShowFullyConfiguredWaveHeightCalculationsView(hydraulicBoundaryLocationCalculations, testForm);
 
@@ -267,7 +267,7 @@
         public void WaveHeightCalculationsView_CalculationUpdated_IllustrationPointsControlCorrectlyUpdated()
         {
             // Setup
-            ObservableList<HydraulicBoundaryLocationCalculation> hydraulicBoundaryLocationCalculations = GetTestHydraulicBoundaryLocationCalculations();
+            IObservableEnumerable<HydraulicBoundaryLocationCalculation> hydraulicBoundaryLocationCalculations = GetTestHydraulicBoundaryLocationCalculations();
 
             ShowFullyConfiguredWaveHeightCalculationsView(hydraulicBoundaryLocationCalculations, testForm);
 
@@ -289,7 +289,7 @@
             var output = new TestHydraulicBoundaryLocationOutput(generalResult);
 
             // Call
-            HydraulicBoundaryLocationCalculation hydraulicBoundaryLocationCalculation = hydraulicBoundaryLocationCalculations[2];
+            HydraulicBoundaryLocationCalculation hydraulicBoundaryLocationCalculation = hydraulicBoundaryLocationCalculations.ElementAt(2);
             hydraulicBoundaryLocationCalculation.Output = output;
             hydraulicBoundaryLocationCalculation.NotifyObservers();
 
@@ -302,7 +302,7 @@
         public void CalculateForSelectedButton_OneSelected_CallsCalculateWaveHeights()
         {
             // Setup
-            ObservableList<HydraulicBoundaryLocationCalculation> hydraulicBoundaryLocationCalculations = GetTestHydraulicBoundaryLocationCalculations();
+            IObservableEnumerable<HydraulicBoundaryLocationCalculation> hydraulicBoundaryLocationCalculations = GetTestHydraulicBoundaryLocationCalculations();
 
             WaveHeightCalculationsView view = ShowFullyConfiguredWaveHeightCalculationsView(hydraulicBoundaryLocationCalculations, testForm);
 
@@ -386,7 +386,7 @@
 
             mockRepository.ReplayAll();
 
-            ObservableList<HydraulicBoundaryLocationCalculation> hydraulicBoundaryLocationCalculations = GetTestHydraulicBoundaryLocationCalculations();
+            IObservableEnumerable<HydraulicBoundaryLocationCalculation> hydraulicBoundaryLocationCalculations = GetTestHydraulicBoundaryLocationCalculations();
 
             WaveHeightCalculationsView view = ShowWaveHeightCalculationsView(hydraulicBoundaryLocationCalculations,
                                                                              assessmentSection,
@@ -458,7 +458,7 @@
 
             mockRepository.ReplayAll();
 
-            ObservableList<HydraulicBoundaryLocationCalculation> hydraulicBoundaryLocationCalculations = GetTestHydraulicBoundaryLocationCalculations();
+            IObservableEnumerable<HydraulicBoundaryLocationCalculation> hydraulicBoundaryLocationCalculations = GetTestHydraulicBoundaryLocationCalculations();
 
             WaveHeightCalculationsView view = ShowWaveHeightCalculationsView(hydraulicBoundaryLocationCalculations,
                                                                              assessmentSection,
@@ -529,7 +529,7 @@
 
             mockRepository.ReplayAll();
 
-            ObservableList<HydraulicBoundaryLocationCalculation> hydraulicBoundaryLocationCalculations = GetTestHydraulicBoundaryLocationCalculations();
+            IObservableEnumerable<HydraulicBoundaryLocationCalculation> hydraulicBoundaryLocationCalculations = GetTestHydraulicBoundaryLocationCalculations();
 
             WaveHeightCalculationsView view = ShowWaveHeightCalculationsView(hydraulicBoundaryLocationCalculations,
                                                                              assessmentSection,
@@ -588,7 +588,7 @@
                                 });
         }
 
-        private static WaveHeightCalculationsView ShowWaveHeightCalculationsView(ObservableList<HydraulicBoundaryLocationCalculation> calculations,
+        private static WaveHeightCalculationsView ShowWaveHeightCalculationsView(IObservableEnumerable<HydraulicBoundaryLocationCalculation> calculations,
                                                                                  IAssessmentSection assessmentSection,
                                                                                  double norm,
                                                                                  string categoryBoundaryName,
@@ -605,7 +605,7 @@
             return view;
         }
 
-        private static WaveHeightCalculationsView ShowFullyConfiguredWaveHeightCalculationsView(ObservableList<HydraulicBoundaryLocationCalculation> calculations,
+        private static WaveHeightCalculationsView ShowFullyConfiguredWaveHeightCalculationsView(IObservableEnumerable<HydraulicBoundaryLocationCalculation> calculations,
                                                                                                 Form form)
         {
             var assessmentSection = new ObservableTestAssessmentSectionStub();