diff --git a/ENI2/DetailViewControls/PortCallDetailControl.xaml.cs b/ENI2/DetailViewControls/PortCallDetailControl.xaml.cs
index e59ea133..aaf976c8 100644
--- a/ENI2/DetailViewControls/PortCallDetailControl.xaml.cs
+++ b/ENI2/DetailViewControls/PortCallDetailControl.xaml.cs
@@ -361,6 +361,13 @@ namespace ENI2.DetailViewControls
         {
             if (this._currentTemplate == null) return;
 
+            // confirm overwrite of waste disposal service provider
+            if (this.textBox_WasteDisposalServiceProvider.Text.Length > 0)
+            {
+                if (MessageBox.Show(Properties.Resources.textConfirmWSDPOverwrite, Properties.Resources.textConfirmation, MessageBoxButton.YesNo, MessageBoxImage.Question, MessageBoxResult.No)
+                    == MessageBoxResult.No) { return; }
+            }
+
             this._undoTemplate = createFromCurrentText(null, null);
 
             this.textBox_AgentCity.Text = this._currentTemplate.AgentCity;
diff --git a/ENI2/Properties/Resources.Designer.cs b/ENI2/Properties/Resources.Designer.cs
index cfca18fc..c499c4c4 100644
--- a/ENI2/Properties/Resources.Designer.cs
+++ b/ENI2/Properties/Resources.Designer.cs
@@ -2173,6 +2173,15 @@ namespace ENI2.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to The existing value for the waste disposal service provider will be overwritten. Proceed?.
+        /// </summary>
+        public static string textConfirmWSDPOverwrite {
+            get {
+                return ResourceManager.GetString("textConfirmWSDPOverwrite", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Construction characteristics.
         /// </summary>
diff --git a/ENI2/Properties/Resources.resx b/ENI2/Properties/Resources.resx
index bdca0024..81f42998 100644
--- a/ENI2/Properties/Resources.resx
+++ b/ENI2/Properties/Resources.resx
@@ -2257,4 +2257,7 @@
   <data name="textNSWStatus" xml:space="preserve">
     <value>NSW-Status</value>
   </data>
+  <data name="textConfirmWSDPOverwrite" xml:space="preserve">
+    <value>The existing value for the waste disposal service provider will be overwritten. Proceed?</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/ENI2/SheetDisplayControls/PortControl.xaml.cs b/ENI2/SheetDisplayControls/PortControl.xaml.cs
index 4c0680c3..e8b70e4c 100644
--- a/ENI2/SheetDisplayControls/PortControl.xaml.cs
+++ b/ENI2/SheetDisplayControls/PortControl.xaml.cs
@@ -339,6 +339,13 @@ namespace ENI2.SheetDisplayControls
         {
             if (this._currentTemplate == null) return;
 
+            // confirm overwrite of waste disposal service provider
+            if (this.textBox_WasteDisposalServiceProvider.Text.Length > 0)
+            {
+                if (MessageBox.Show(Properties.Resources.textConfirmWSDPOverwrite, Properties.Resources.textConfirmation, MessageBoxButton.YesNo, MessageBoxImage.Question, MessageBoxResult.No)
+                    == MessageBoxResult.No) { return; }
+            }
+
             this._undoTemplate = createFromCurrentText(null, null);
 
             this.textBox_AgentCity.Text = this._currentTemplate.AgentCity;