At bottom of the home page are a series of tabs, click the one titled Data.  On this page left hand column, second paragraph you will see River Watch Data Tool by Station.  

Click this and you will see a box titled Select Station.  Select 236 which is the South Platte Waterton Station and click this and it will bring you to the Water Quality Parameters and Macroinvertebrate Parameters.  To the right is a User Guide that explains how to navigate and explore the data tool.  Below that is Macroinvertebrate Parameters that explains the data and math.

Also on the Data page, left hand column, first sentence, first paragraph is a link titled StoryMap.  This link takes you to a tab labeled Station that has a map of all the active and inactive sites in Colorado.  If you click a station on the map you can go down to Chemical Data and clicking this will take you back to the Data Tool with water quality and macroinvertrevaretes data for that particular site.  Also there is a Macroinvertebrate tab next to station that takes you to active and inactive sites which you can click.  On the right there is an explanation of the various measures and results that you see when you click a particular site.