public UtilityNetwork GetUtilityNetwork()

{
  static UtilityNetwork GetUtilityNetworkFromLayer(Layer unLayer)
  {
    UtilityNetwork utilityNetwork = null;

    Layer layer = MapView.Active.Map.GetLayersAsFlattenedList().First();

    // This routine obtains a utility network from a FeatureLayer, SubtypeGroupLayer, or UtilityNetworkLayer
    if (layer is UtilityNetworkLayer)
    {
      UtilityNetworkLayer utilityNetworkLayer = layer as UtilityNetworkLayer;
      utilityNetwork = utilityNetworkLayer.GetUtilityNetwork();
    }

    else if (layer is SubtypeGroupLayer)
    {
      CompositeLayer compositeLayer = layer as CompositeLayer;
      utilityNetwork = GetUtilityNetworkFromLayer(compositeLayer.Layers.First());
    }

    else if (layer is FeatureLayer)
    {
      FeatureLayer featureLayer = layer as FeatureLayer;
      using (FeatureClass featureClass = featureLayer.GetFeatureClass())
      {
        if (featureClass.IsControllerDatasetSupported())
        {
          IReadOnlyList<Dataset> controllerDatasets = new List<Dataset>();
          controllerDatasets = featureClass.GetControllerDatasets();
          foreach (Dataset controllerDataset in controllerDatasets)
          {
            if (controllerDataset is UtilityNetwork)
            {
              utilityNetwork = controllerDataset as UtilityNetwork;
            }
            else
            {
              controllerDataset.Dispose();
            }
          }
        }
      }
    }
    return utilityNetwork;
  }
}