Index: Ringtoets/GrassCoverErosionOutwards/src/Ringtoets.GrassCoverErosionOutwards.Service/GrassCoverErosionOutwardsWaveConditionsCalculationService.cs
===================================================================
diff -u -re2892835ceb1c916be9a9122ba372858f20b981a -rb4b93f81c63d098edfd9e50ce1c94e37903e52f6
--- Ringtoets/GrassCoverErosionOutwards/src/Ringtoets.GrassCoverErosionOutwards.Service/GrassCoverErosionOutwardsWaveConditionsCalculationService.cs	(.../GrassCoverErosionOutwardsWaveConditionsCalculationService.cs)	(revision e2892835ceb1c916be9a9122ba372858f20b981a)
+++ Ringtoets/GrassCoverErosionOutwards/src/Ringtoets.GrassCoverErosionOutwards.Service/GrassCoverErosionOutwardsWaveConditionsCalculationService.cs	(.../GrassCoverErosionOutwardsWaveConditionsCalculationService.cs)	(revision b4b93f81c63d098edfd9e50ce1c94e37903e52f6)
@@ -123,7 +123,7 @@
                 failureMechanism.GeneralInput.N);
             string preprocessorDirectory = assessmentSection.HydraulicBoundaryDatabase.EffectivePreprocessorDirectory();
 
-            TotalWaterLevelCalculations = calculation.InputParameters.WaterLevels.Count();
+            TotalWaterLevelCalculations = calculation.InputParameters.GetWaterLevels(calculation.InputParameters.AssessmentLevel).Count();
 
             try
             {
Index: Ringtoets/GrassCoverErosionOutwards/test/Ringtoets.GrassCoverErosionOutwards.Integration.Test/GrassCoverErosionOutwardsWaveConditionsCalculationActivityIntegrationTest.cs
===================================================================
diff -u -rc0532d07766ecad2566f7cfa4a97a9aeb6e8540c -rb4b93f81c63d098edfd9e50ce1c94e37903e52f6
--- Ringtoets/GrassCoverErosionOutwards/test/Ringtoets.GrassCoverErosionOutwards.Integration.Test/GrassCoverErosionOutwardsWaveConditionsCalculationActivityIntegrationTest.cs	(.../GrassCoverErosionOutwardsWaveConditionsCalculationActivityIntegrationTest.cs)	(revision c0532d07766ecad2566f7cfa4a97a9aeb6e8540c)
+++ Ringtoets/GrassCoverErosionOutwards/test/Ringtoets.GrassCoverErosionOutwards.Integration.Test/GrassCoverErosionOutwardsWaveConditionsCalculationActivityIntegrationTest.cs	(.../GrassCoverErosionOutwardsWaveConditionsCalculationActivityIntegrationTest.cs)	(revision b4b93f81c63d098edfd9e50ce1c94e37903e52f6)
@@ -178,7 +178,7 @@
                                                                                           assessmentSection.GrassCoverErosionOutwards,
                                                                                           assessmentSection);
 
-            int nrOfCalculators = calculation.InputParameters.WaterLevels.Count();
+            int nrOfCalculators = calculation.InputParameters.GetWaterLevels(calculation.InputParameters.AssessmentLevel).Count();
 
             var mockRepository = new MockRepository();
             var calculatorFactory = mockRepository.StrictMock<IHydraRingCalculatorFactory>();
@@ -204,7 +204,7 @@
                     CalculationServiceTestHelper.AssertCalculationStartMessage(msgs[3]);
 
                     var i = 3;
-                    foreach (RoundedDouble waterLevel in calculation.InputParameters.WaterLevels)
+                    foreach (RoundedDouble waterLevel in calculation.InputParameters.GetWaterLevels(calculation.InputParameters.AssessmentLevel))
                     {
                         Assert.AreEqual($"Berekening voor waterstand '{waterLevel}' is gestart.", msgs[i + 1]);
                         StringAssert.StartsWith("Golfcondities berekening is uitgevoerd op de tijdelijke locatie", msgs[i + 2]);
@@ -233,7 +233,7 @@
                                                                                           assessmentSection.GrassCoverErosionOutwards,
                                                                                           assessmentSection);
 
-            int nrOfCalculators = calculation.InputParameters.WaterLevels.Count();
+            int nrOfCalculators = calculation.InputParameters.GetWaterLevels(calculation.InputParameters.AssessmentLevel).Count();
 
             var mockRepository = new MockRepository();
             var calculatorFactory = mockRepository.StrictMock<IHydraRingCalculatorFactory>();
@@ -252,7 +252,7 @@
                 activity.Run();
 
                 // Assert
-                RoundedDouble[] waterLevels = calculation.InputParameters.WaterLevels.ToArray();
+                RoundedDouble[] waterLevels = calculation.InputParameters.GetWaterLevels(calculation.InputParameters.AssessmentLevel).ToArray();
                 for (var i = 0; i < waterLevels.Length; i++)
                 {
                     string text = $"Stap {i + 1} van {waterLevels.Length} | Waterstand '{waterLevels[i]}' berekenen.";
@@ -281,7 +281,7 @@
                                                                                           assessmentSection);
 
             var waveConditionsCosineCalculator = new TestWaveConditionsCosineCalculator();
-            int nrOfCalculators = calculation.InputParameters.WaterLevels.Count();
+            int nrOfCalculators = calculation.InputParameters.GetWaterLevels(calculation.InputParameters.AssessmentLevel).Count();
 
             var mockRepository = new MockRepository();
             var calculatorFactory = mockRepository.StrictMock<IHydraRingCalculatorFactory>();
@@ -317,7 +317,7 @@
                                                                                  mechanismSpecificNorm,
                                                                                  input.ForeshoreProfile.Geometry.Select(c => new HydraRingForelandPoint(c.X, c.Y)),
                                                                                  new HydraRingBreakWater(BreakWaterTypeHelper.GetHydraRingBreakWaterType(breakWaterType), input.BreakWater.Height),
-                                                                                 calculation.InputParameters.WaterLevels.ElementAt(waterLevelIndex++),
+                                                                                 calculation.InputParameters.GetWaterLevels(calculation.InputParameters.AssessmentLevel).ElementAt(waterLevelIndex++),
                                                                                  generalInput.GeneralWaveConditionsInput.A,
                                                                                  generalInput.GeneralWaveConditionsInput.B,
                                                                                  generalInput.GeneralWaveConditionsInput.C);
@@ -363,7 +363,7 @@
                 TestHelper.AssertLogMessages(() => activity.Run(), messages =>
                 {
                     string[] msgs = messages.ToArray();
-                    RoundedDouble firstWaterLevel = calculation.InputParameters.WaterLevels.First();
+                    RoundedDouble firstWaterLevel = calculation.InputParameters.GetWaterLevels(calculation.InputParameters.AssessmentLevel).First();
 
                     Assert.AreEqual(8, msgs.Length);
                     Assert.AreEqual($"Golfcondities berekenen voor '{calculation.Name}' is gestart.", msgs[0]);
@@ -397,7 +397,7 @@
                                                                                           assessmentSection.GrassCoverErosionOutwards,
                                                                                           assessmentSection);
 
-            int nrOfCalculators = calculation.InputParameters.WaterLevels.Count();
+            int nrOfCalculators = calculation.InputParameters.GetWaterLevels(calculation.InputParameters.AssessmentLevel).Count();
 
             var mockRepository = new MockRepository();
             var calculatorFactory = mockRepository.StrictMock<IHydraRingCalculatorFactory>();
@@ -445,7 +445,7 @@
                 LastErrorFileContent = lastErrorFileContent
             };
 
-            int nrOfCalculators = calculation.InputParameters.WaterLevels.Count();
+            int nrOfCalculators = calculation.InputParameters.GetWaterLevels(calculation.InputParameters.AssessmentLevel).Count();
 
             var mockRepository = new MockRepository();
             var calculatorFactory = mockRepository.StrictMock<IHydraRingCalculatorFactory>();
@@ -491,7 +491,7 @@
                 LastErrorFileContent = lastErrorFileContent
             };
 
-            int nrOfCalculators = calculation.InputParameters.WaterLevels.Count();
+            int nrOfCalculators = calculation.InputParameters.GetWaterLevels(calculation.InputParameters.AssessmentLevel).Count();
 
             var mockRepository = new MockRepository();
             var calculatorFactory = mockRepository.StrictMock<IHydraRingCalculatorFactory>();
@@ -536,7 +536,7 @@
                                                                                           validFilePath,
                                                                                           grassCoverErosionOutwardsFailureMechanism,
                                                                                           assessmentSection);
-            int nrOfCalculators = calculation.InputParameters.WaterLevels.Count();
+            int nrOfCalculators = calculation.InputParameters.GetWaterLevels(calculation.InputParameters.AssessmentLevel).Count();
 
             var calculatorFactory = mockRepository.StrictMock<IHydraRingCalculatorFactory>();
             calculatorFactory.Expect(cf => cf.CreateWaveConditionsCosineCalculator(testDataPath, string.Empty))
@@ -582,7 +582,7 @@
                                                                                           validFilePath,
                                                                                           grassCoverErosionOutwardsFailureMechanism,
                                                                                           assessmentSection);
-            int nrOfCalculators = calculation.InputParameters.WaterLevels.Count();
+            int nrOfCalculators = calculation.InputParameters.GetWaterLevels(calculation.InputParameters.AssessmentLevel).Count();
 
             var calculatorFactory = mockRepository.StrictMock<IHydraRingCalculatorFactory>();
             calculatorFactory.Expect(cf => cf.CreateWaveConditionsCosineCalculator(testDataPath, validPreprocessorDirectory))
@@ -628,7 +628,7 @@
                                                                                           validFilePath,
                                                                                           grassCoverErosionOutwardsFailureMechanism,
                                                                                           assessmentSection);
-            int nrOfCalculators = calculation.InputParameters.WaterLevels.Count();
+            int nrOfCalculators = calculation.InputParameters.GetWaterLevels(calculation.InputParameters.AssessmentLevel).Count();
 
             var calculatorFactory = mockRepository.StrictMock<IHydraRingCalculatorFactory>();
             calculatorFactory.Expect(cf => cf.CreateWaveConditionsCosineCalculator(testDataPath, string.Empty))
Index: Ringtoets/GrassCoverErosionOutwards/test/Ringtoets.GrassCoverErosionOutwards.Service.Test/GrassCoverErosionOutwardsWaveConditionsCalculationServiceTest.cs
===================================================================
diff -u -r401ea38da560543cd91415c326b9463976b2e80a -rb4b93f81c63d098edfd9e50ce1c94e37903e52f6
--- Ringtoets/GrassCoverErosionOutwards/test/Ringtoets.GrassCoverErosionOutwards.Service.Test/GrassCoverErosionOutwardsWaveConditionsCalculationServiceTest.cs	(.../GrassCoverErosionOutwardsWaveConditionsCalculationServiceTest.cs)	(revision 401ea38da560543cd91415c326b9463976b2e80a)
+++ Ringtoets/GrassCoverErosionOutwards/test/Ringtoets.GrassCoverErosionOutwards.Service.Test/GrassCoverErosionOutwardsWaveConditionsCalculationServiceTest.cs	(.../GrassCoverErosionOutwardsWaveConditionsCalculationServiceTest.cs)	(revision b4b93f81c63d098edfd9e50ce1c94e37903e52f6)
@@ -449,7 +449,7 @@
                     CalculationServiceTestHelper.AssertCalculationStartMessage(msgs[0]);
 
                     var i = 0;
-                    foreach (RoundedDouble waterLevel in calculation.InputParameters.WaterLevels)
+                    foreach (RoundedDouble waterLevel in calculation.InputParameters.GetWaterLevels(calculation.InputParameters.AssessmentLevel))
                     {
                         Assert.AreEqual($"Berekening voor waterstand '{waterLevel}' is gestart.", msgs[i + 1]);
                         StringAssert.StartsWith("Golfcondities berekening is uitgevoerd op de tijdelijke locatie", msgs[i + 2]);
@@ -517,7 +517,7 @@
                     CalculationServiceTestHelper.AssertCalculationStartMessage(msgs[0]);
 
                     var i = 0;
-                    foreach (RoundedDouble waterLevel in calculation.InputParameters.WaterLevels)
+                    foreach (RoundedDouble waterLevel in calculation.InputParameters.GetWaterLevels(calculation.InputParameters.AssessmentLevel))
                     {
                         Assert.AreEqual($"Berekening voor waterstand '{waterLevel}' is gestart.", msgs[i + 1]);
                         StringAssert.StartsWith("Golfcondities berekening is uitgevoerd op de tijdelijke locatie", msgs[i + 2]);
@@ -585,7 +585,7 @@
                                                                                  mechanismSpecificNorm,
                                                                                  input.ForeshoreProfile.Geometry.Select(c => new HydraRingForelandPoint(c.X, c.Y)),
                                                                                  new HydraRingBreakWater(BreakWaterTypeHelper.GetHydraRingBreakWaterType(breakWaterType), input.BreakWater.Height),
-                                                                                 calculation.InputParameters.WaterLevels.ElementAt(waterLevelIndex++),
+                                                                                 calculation.InputParameters.GetWaterLevels(calculation.InputParameters.AssessmentLevel).ElementAt(waterLevelIndex++),
                                                                                  generalInput.GeneralWaveConditionsInput.A,
                                                                                  generalInput.GeneralWaveConditionsInput.B,
                                                                                  generalInput.GeneralWaveConditionsInput.C);
@@ -761,7 +761,7 @@
 
                     CalculationServiceTestHelper.AssertCalculationStartMessage(msgs[0]);
 
-                    RoundedDouble[] waterLevels = calculation.InputParameters.WaterLevels.ToArray();
+                    RoundedDouble[] waterLevels = calculation.InputParameters.GetWaterLevels(calculation.InputParameters.AssessmentLevel).ToArray();
                     RoundedDouble waterLevelUpperBoundaryRevetment = waterLevels[0];
                     RoundedDouble waterLevelMiddleRevetment = waterLevels[1];
                     RoundedDouble waterLevelLowerBoundaryRevetment = waterLevels[2];
@@ -839,7 +839,7 @@
                 };
 
                 // Assert
-                RoundedDouble[] waterLevels = calculation.InputParameters.WaterLevels.ToArray();
+                RoundedDouble[] waterLevels = calculation.InputParameters.GetWaterLevels(calculation.InputParameters.AssessmentLevel).ToArray();
                 RoundedDouble waterLevelUpperBoundaryRevetment = waterLevels[0];
                 RoundedDouble waterLevelMiddleRevetment = waterLevels[1];
                 RoundedDouble waterLevelLowerBoundaryRevetment = waterLevels[2];
Index: Ringtoets/Revetment/src/Ringtoets.Revetment.Service/WaveConditionsCalculationServiceBase.cs
===================================================================
diff -u -r35525b6135cc111e4af3803f7dcce0d7528bbb16 -rb4b93f81c63d098edfd9e50ce1c94e37903e52f6
--- Ringtoets/Revetment/src/Ringtoets.Revetment.Service/WaveConditionsCalculationServiceBase.cs	(.../WaveConditionsCalculationServiceBase.cs)	(revision 35525b6135cc111e4af3803f7dcce0d7528bbb16)
+++ Ringtoets/Revetment/src/Ringtoets.Revetment.Service/WaveConditionsCalculationServiceBase.cs	(.../WaveConditionsCalculationServiceBase.cs)	(revision b4b93f81c63d098edfd9e50ce1c94e37903e52f6)
@@ -149,7 +149,7 @@
             var calculationsFailed = 0;
             var outputs = new List<WaveConditionsOutput>();
 
-            RoundedDouble[] waterLevels = waveConditionsInput.WaterLevels.ToArray();
+            RoundedDouble[] waterLevels = waveConditionsInput.GetWaterLevels(waveConditionsInput.AssessmentLevel).ToArray();
             foreach (RoundedDouble waterLevel in waterLevels.TakeWhile(waterLevel => !Canceled))
             {
                 try
@@ -399,7 +399,7 @@
             }
             else
             {
-                if (!input.WaterLevels.Any())
+                if (!input.GetWaterLevels(input.AssessmentLevel).Any())
                 {
                     messages.Add(Resources.WaveConditionsCalculationService_ValidateInput_No_derived_WaterLevels);
                 }