diff --git a/las_outputs.py b/las_outputs.py
index 8746ac0..defa76c 100644
--- a/las_outputs.py
+++ b/las_outputs.py
@@ -160,17 +160,17 @@ def calculate_volumes(profile_name, survey_date, csv_output_dir, ch_limits, volu
         # Create new dataframe if csv does not exist
         volumes = pd.DataFrame()
 
-    for current_date in profiles.columns:
-        # Get Nielsen erosion volumes
-        chainage = profiles.loc[:, current_date].dropna().index
-        elevation = profiles.loc[:, current_date].dropna().values
-        try:
-            volume = nielsen_volumes.volume_available(chainage, elevation, ch_min)
-        except ValueError:
-            volume = np.nan        
+    # Get Nielsen erosion volumes for current survey date
+    current_survey = 'Elevation_' + survey_date
+    chainage = profiles.loc[:, current_survey].dropna().index
+    elevation = profiles.loc[:, current_survey].dropna().values
+    try:
+        volume = nielsen_volumes.volume_available(chainage, elevation, ch_min)
+    except ValueError:
+        volume = np.nan
 
-        # Update spreadsheet
-        volumes.loc[profile_name, 'Volume_' + survey_date] = volume
+    # Update spreadsheet
+    volumes.loc[profile_name, 'Volume_' + survey_date] = volume
 
     # Save updated volumes spreadsheet
     volumes = volumes[volumes.columns.sort_values()]