diff --git a/assets/src/scripts/monitoring-location/components/hydrograph/data-loading-indicator.js b/assets/src/scripts/monitoring-location/components/hydrograph/data-loading-indicator.js
index ef5de8a48739faa8e7b3448f2dee69d7e9e25cf2..59e4bf9e13d1ce6c2ab3db25a1010a3d0a03e982 100644
--- a/assets/src/scripts/monitoring-location/components/hydrograph/data-loading-indicator.js
+++ b/assets/src/scripts/monitoring-location/components/hydrograph/data-loading-indicator.js
@@ -4,6 +4,12 @@ import config from 'ui/config';
 import {mediaQuery} from 'ui/utils';
 import {drawLoadingIndicator} from 'd3render/loading-indicator';
 
+/*
+ * Makes the loading indicator visible if isVisible otherwise removes the loading indicator.
+ * The layoutHeight is used to roughly center the spinner within the hydrograph.
+ * @param {Boolean} isVisible
+ * @param {Number} layoutHeight
+ */
 export const showDataLoadingIndicator = function(isVisible, layoutHeight) {
     const container = select('#hydrograph-loading-indicator-container')
         .call(drawLoadingIndicator, {