--- a/artifacts/src/main/java/org/dive4elements/river/artifacts/sinfo/tkhstate/TkhCalculation.java	Wed Jun 06 14:16:28 2018 +0200
+++ b/artifacts/src/main/java/org/dive4elements/river/artifacts/sinfo/tkhstate/TkhCalculation.java	Wed Jun 06 14:17:18 2018 +0200
@@ -63,11 +63,20 @@
         final RiverInfo riverInfo = new RiverInfo(river);
         final DoubleRange calcRange = access.getRange();
 
+        final String calcModeLabel = Resources.getMsg(this.context.getMeta(), sinfo.getCalculationMode().name());
+        final String user = CalculationUtils.findArtifactUser(this.context, sinfo);
+
         final Calculation problems = new Calculation();
 
         /* find relevant bed-heights */
         final List<BedHeight> defaultBedHeights = new DefaultBedHeights(river).getBedHeights(problems);
         final Collection<BedHeightsFinder> bedHeights = BedHeightsFinder.createTkhBedHeights(problems, calcRange, defaultBedHeights);
+
+        if (defaultBedHeights.isEmpty()) {
+            final TkhCalculationResults results = new TkhCalculationResults(calcModeLabel, user, riverInfo, calcRange, "");
+            return new CalculationResult(results, problems);
+        }
+
         final double[] stations = extractStations(bedHeights);
 
         /* misuse winfo-artifact to calculate waterlevels in the same way */
@@ -78,10 +87,6 @@
 
         final RiverInfoProvider infoProvider = RiverInfoProvider.forRange(this.context, river, calcRange);
 
-        final String user = CalculationUtils.findArtifactUser(this.context, sinfo);
-
-        final String calcModeLabel = Resources.getMsg(this.context.getMeta(), sinfo.getCalculationMode().name());
-
         final WaterlevelDescriptionBuilder descBuilder = new WaterlevelDescriptionBuilder(winfo, this.context);
         final String descriptionHeader = descBuilder.getColumnHeader();
 
@@ -126,10 +131,7 @@
 
     private WQKms[] calculateWaterlevels(final WINFOArtifact winfo, final double[] stations, final Calculation problems) {
 
-        // FIXME: we take kms from step, but instead we would like to take kms from bedheights
-        // FIXME: this will definitely break the serialization of the winfo artifact
-
-        final CalculationResult waterlevelData = winfo.getWaterlevelData(this.context);
+        final CalculationResult waterlevelData = winfo.computeWaterlevelData(stations);
 
         /* copy all problems */
         final Calculation winfoProblems = waterlevelData.getReport();