Multiple efforts to address elevated selenium concentrations in the Lower Gunnison and Colorado Rivers within Colorado are on-going
The most active effort is related to the Selenium Management Program (SMP) facilitated by the US Bureau of Reclamation.
Details and archives can be found here
Additionally – there is a voluntary group of landowners, water users and agency folks working in a cooperative and proactive fashion to “protect the agricultural heritage” of the basin.
In 2018, the USGS published a report analyzing streamflow and selenium loads in the Gunnison and its tributaries near Delta. It can be found here.

The area analyzed in the above report.
The following map shows the selenium mobilization potential – this information was produced by the Colorado River District in cooperation with the NRCS Conservation Innovation Grant (CIG) Program and utilized as part of the targeting for Lower Gunnison Project activities

Relative selenium loading potential map
Downloadable PDF Lower Gunnison Basin Selenium Mobilization Map