diff --git a/docs/env_vars.md b/docs/env_vars.md
index 0b021409..dc83f004 100644
--- a/docs/env_vars.md
+++ b/docs/env_vars.md
@@ -71,3 +71,7 @@ This project uses environment variables to configure certain aspects of the appl
 
 - The cache key and timeout length for the Google Calendar events
 - Hard-coded in `settings.py` in all environments
+
+### `CI`
+
+- If set, will set SITE_ID to 1 in `settings.py`.