--- a/flys-artifacts/ChangeLog	Fri Oct 05 23:21:18 2012 +0200
+++ b/flys-artifacts/ChangeLog	Sat Oct 06 00:25:28 2012 +0200
@@ -1,3 +1,8 @@
+2012-10-06	Christian Lins	<christian.lins@intevation.de>
+
+	* src/main/java/de/intevation/flys/artifacts/model/WaterlevelFacet.java:
+	  Fix for ArrayIndexOutOfBoundsException (#818).
+
 2012-10-05	Christian Lins	<christian.lins@intevation.de>
 
 	* src/main/java/de/intevation/flys/exports/TimeseriesChartGenerator.java:

--- a/flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/WaterlevelFacet.java	Fri Oct 05 23:21:18 2012 +0200
+++ b/flys-artifacts/src/main/java/de/intevation/flys/artifacts/model/WaterlevelFacet.java	Sat Oct 06 00:25:28 2012 +0200
@@ -1,14 +1,11 @@
 package de.intevation.flys.artifacts.model;
 
 import de.intevation.artifactdatabase.state.Facet;
-
 import de.intevation.artifacts.Artifact;
 import de.intevation.artifacts.CallContext;
-
 import de.intevation.flys.artifacts.FLYSArtifact;
-
+import de.intevation.flys.artifacts.math.Linear;
 import de.intevation.flys.artifacts.states.DefaultState.ComputeType;
-import de.intevation.flys.artifacts.math.Linear;
 
 import org.apache.log4j.Logger;
 
@@ -45,6 +42,7 @@
      * Get waterlevel data.
      * @return a WQKms at given index.
      */
+    @Override
     public Object getData(Artifact artifact, CallContext context) {
 
         if (logger.isDebugEnabled()) {
@@ -52,6 +50,11 @@
                 " /stateId: " + stateId);
         }
 
+        if (artifact == null) {
+            logger.error("WaterlevelFacet.getData: artifact is null");
+            return null;
+        }
+
         FLYSArtifact winfo = (FLYSArtifact) artifact;
 
         CalculationResult res = (CalculationResult)
@@ -62,11 +65,6 @@
             return null;
         }
 
-        if (winfo == null) {
-            logger.error("WaterlevelFacet.getData: artifact is null");
-            return null;
-        }
-
         WQKms [] wqkms = getWQKms(res);
         Object KM = context.getContextValue("currentKm");
         if (KM != null) {
@@ -92,18 +90,20 @@
                     idx--;
                 }
             }
+
             WQKms resultWQKms = new WQKms();
-            if (idx != -1 && idx < size) {
+            if ((idx != -1) && (idx < size) && (idx - mod != -1) && (idx - mod < size)) {
                 double inW = Linear.linear(
                     km,
-                    wqkmsI.getKm(idx), wqkmsI.getKm(idx-mod),
-                    wqkmsI.getW(idx), wqkmsI.getW(idx-mod));
+                    wqkmsI.getKm(idx), wqkmsI.getKm(idx - mod),
+                    wqkmsI.getW(idx), wqkmsI.getW(idx - mod));
                 double inQ = Linear.linear(
                     km,
-                    wqkmsI.getKm(idx), wqkmsI.getKm(idx-mod),
-                    wqkmsI.getQ(idx), wqkmsI.getQ(idx-mod));
+                    wqkmsI.getKm(idx), wqkmsI.getKm(idx - mod),
+                    wqkmsI.getQ(idx), wqkmsI.getQ(idx - mod));
                 resultWQKms.add(inW, inQ, km);
             }
+
             return resultWQKms;
         }