--- a/artifacts/src/main/java/org/dive4elements/river/artifacts/sinfo/tkhstate/BedHeightsFinder.java	Mon Mar 19 14:13:37 2018 +0100
+++ b/artifacts/src/main/java/org/dive4elements/river/artifacts/sinfo/tkhstate/BedHeightsFinder.java	Mon Mar 19 16:32:42 2018 +0100
@@ -37,6 +37,12 @@
 
     private final NavigableMap<Double, BedHeightValue> values;
 
+    private double meanBedHeight;
+
+    private double minBedHeight;
+
+    private double maxBedHeight;
+
     /**
      * Create bed height finders from a collection of bed heights.
      */
@@ -139,23 +145,53 @@
     }
 
     public double getMeanBedHeight(final double km) {
+        getBedHeights(km);
+        return this.meanBedHeight;
+    }
 
-        if (this.values.containsKey(km))
-            return this.values.get(km).getHeight();
+    public double getMinBedHeight(final double km) {
+        getBedHeights(km);
+        return this.minBedHeight;
+    }
+
+    public double getMaxBedHeight(final double km) {
+        getBedHeights(km);
+        return this.maxBedHeight;
+    }
+
+    private boolean getBedHeights(final double km) {
+        if (this.values.containsKey(km)) {
+            this.meanBedHeight = (this.values.get(km).getHeight() != null) ? this.values.get(km).getHeight().doubleValue() : Double.NaN;
+            this.minBedHeight = (this.values.get(km).getMinHeight() != null) ? this.values.get(km).getMinHeight().doubleValue() : Double.NaN;
+            this.maxBedHeight = (this.values.get(km).getMaxHeight() != null) ? this.values.get(km).getMaxHeight().doubleValue() : Double.NaN;
+            return true;
+        }
 
         final Entry<Double, BedHeightValue> floorEntry = this.values.floorEntry(km);
         final Entry<Double, BedHeightValue> ceilingEntry = this.values.ceilingEntry(km);
 
-        if (floorEntry == null || ceilingEntry == null)
-            return Double.NaN;
+        if (floorEntry == null || ceilingEntry == null) {
+            this.meanBedHeight = Double.NaN;
+            this.minBedHeight = Double.NaN;
+            this.maxBedHeight = Double.NaN;
+            return false;
+        }
 
-        final double floorKm = floorEntry.getKey();
-        final double floorHeight = floorEntry.getValue().getHeight();
-        final double ceilKm = ceilingEntry.getKey();
-        final double ceilHeight = ceilingEntry.getValue().getHeight();
+        final double floorKm = floorEntry.getKey().doubleValue();
+        final double ceilKm = ceilingEntry.getKey().doubleValue();
 
         // FIXME: check if we always want that...
 
-        return Linear.linear(km, floorKm, ceilKm, floorHeight, ceilHeight);
+        this.meanBedHeight = interpolate(km, floorKm, ceilKm, floorEntry.getValue().getHeight(), ceilingEntry.getValue().getHeight());
+        this.minBedHeight = interpolate(km, floorKm, ceilKm, floorEntry.getValue().getMinHeight(), ceilingEntry.getValue().getMinHeight());
+        this.maxBedHeight = interpolate(km, floorKm, ceilKm, floorEntry.getValue().getMaxHeight(), ceilingEntry.getValue().getMaxHeight());
+        return true;
+    }
+
+    private double interpolate(final double km, final double floorKm, final double ceilKm, final Double floorHeight, final Double ceilHeight) {
+        if ((floorHeight != null) && (ceilHeight != null))
+            return Linear.linear(km, floorKm, ceilKm, floorHeight, ceilHeight);
+        else
+            return Double.NaN;
     }
 }
\ No newline at end of file

--- a/backend/src/main/java/org/dive4elements/river/model/BedHeightValue.java	Mon Mar 19 14:13:37 2018 +0100
+++ b/backend/src/main/java/org/dive4elements/river/model/BedHeightValue.java	Mon Mar 19 16:32:42 2018 +0100
@@ -47,99 +47,111 @@
     private Double uncertainty;
     private Double dataGap;
     private Double soundingWidth;
+    private Double minHeight;
+    private Double maxHeight;
 
 
     public BedHeightValue() {
     }
 
-    public BedHeightValue(
-        BedHeight bedHeight,
-        Double station,
-        Double height,
-        Double uncertainty,
-        Double dataGap,
-        Double soundingWidth
-    ) {
+    public BedHeightValue(final BedHeight bedHeight, final Double station, final Double height, final Double uncertainty, final Double dataGap,
+            final Double soundingWidth, final Double minHeight, final Double maxHeight) {
         this.bedHeight     = bedHeight;
         this.station       = station;
         this.height        = height;
         this.uncertainty   = uncertainty;
         this.dataGap       = dataGap;
         this.soundingWidth = soundingWidth;
+        this.minHeight = minHeight;
+        this.maxHeight = maxHeight;
     }
 
     @Id
-    @SequenceGenerator(
-        name           = "SEQUENCE_BED_HEIGHT_VALUE_ID_SEQ",
-        sequenceName   = "BED_HEIGHT_VALUES_ID_SEQ",
-        allocationSize = 1)
-    @GeneratedValue(
-        strategy  = GenerationType.SEQUENCE,
-        generator = "SEQUENCE_BED_HEIGHT_VALUE_ID_SEQ")
+    @SequenceGenerator(name = "SEQUENCE_BED_HEIGHT_VALUE_ID_SEQ", sequenceName = "BED_HEIGHT_VALUES_ID_SEQ", allocationSize = 1)
+    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "SEQUENCE_BED_HEIGHT_VALUE_ID_SEQ")
     @Column(name = "id")
     public Integer getId() {
-        return id;
+        return this.id;
     }
 
-    public void setId(Integer id) {
+    public void setId(final Integer id) {
         this.id = id;
     }
 
     @OneToOne
     @JoinColumn(name = "bed_height_id")
     public BedHeight getBedHeight() {
-        return bedHeight;
+        return this.bedHeight;
     }
 
-    public void setBedHeight(BedHeight bedHeight) {
+    public void setBedHeight(final BedHeight bedHeight) {
         this.bedHeight = bedHeight;
     }
 
     @Column(name = "station")
     public Double getStation() {
-        return station;
+        return this.station;
     }
 
-    public void setStation(Double station) {
+    public void setStation(final Double station) {
         this.station = station;
     }
 
     @Column(name = "height")
     public Double getHeight() {
-        return height;
+        return this.height;
     }
 
-    public void setHeight(Double height) {
+    public void setHeight(final Double height) {
         this.height = height;
     }
 
     @Column(name="uncertainty")
     public Double getUncertainty() {
-        return uncertainty;
+        return this.uncertainty;
     }
 
-    public void setUncertainty(Double uncertainty) {
+    public void setUncertainty(final Double uncertainty) {
         this.uncertainty = uncertainty;
     }
 
     @Column(name="data_gap")
     public Double getDataGap() {
-        return dataGap;
+        return this.dataGap;
     }
 
-    public void setDataGap(Double dataGap) {
+    public void setDataGap(final Double dataGap) {
         this.dataGap = dataGap;
     }
 
     @Column(name="sounding_width")
     public Double getSoundingWidth() {
-        return soundingWidth;
+        return this.soundingWidth;
     }
 
-    public void setSoundingWidth(Double soundingWidth) {
+    public void setSoundingWidth(final Double soundingWidth) {
         this.soundingWidth = soundingWidth;
     }
 
+    @Column(name = "min_height")
+    public Double getMinHeight() {
+        return this.minHeight;
+    }
+
+    public void setMinHeight(final Double minHeight) {
+        this.minHeight = minHeight;
+    }
+
+    @Column(name = "max_height")
+    public Double getMaxHeight() {
+        return this.maxHeight;
+    }
+
+    public void setMaxHeight(final Double maxHeight) {
+        this.maxHeight = maxHeight;
+    }
+
+
     public static List<BedHeightValue> getBedHeightValues(
         BedHeight single) {
         Session session = SessionHolder.HOLDER.get();