diff --git a/namespaces/usgs/README.md b/namespaces/usgs/README.md
index aaeacb36..6f99f263 100644
--- a/namespaces/usgs/README.md
+++ b/namespaces/usgs/README.md
@@ -16,13 +16,13 @@ Examples:
 * An HU06: https://geoconnex.us/usgs/hydrologic-unit/070700
 * An HU08: https://geoconnex.us/usgs/hydrologic-unit/07070005
 
-## mainstem
+## mainstems
 
 Mainstem IDs for rivers not defined in reference rivers.
 
 Examples: 
-* https://geoconnex.us/usgs/mainstem/9085326
-* https://geoconnex.us/usgs/mainstem/7419739
+* https://geoconnex.us/usgs/mainstems/9085326
+* https://geoconnex.us/usgs/mainstems/7419739
 
 ## monitoring-location
 
diff --git a/namespaces/usgs/mainstem/mainstem.csv b/namespaces/usgs/mainstem/mainstem.csv
deleted file mode 100644
index f35830e8..00000000
--- a/namespaces/usgs/mainstem/mainstem.csv
+++ /dev/null
@@ -1,2 +0,0 @@
-id,target,creator,description
-https://geoconnex.us//usgs/mainstem/([0-9_]+).*$, https://hydro.nationalmap.gov/arcgis/rest/services/3DHP_all/MapServer/1/query?where=mainstemid%3D'https%3A%2F%2Fgeoconnex.us%2Fusgs%2Fmainstem%2F$1'&outFields=*&f=geojson&inSR=4269&outSR=4326, dblodgett@usgs.gov, USGS Mainstem ID
diff --git a/namespaces/usgs/mainstems/mainstems.csv b/namespaces/usgs/mainstems/mainstems.csv
new file mode 100644
index 00000000..4738b539
--- /dev/null
+++ b/namespaces/usgs/mainstems/mainstems.csv
@@ -0,0 +1,2 @@
+id,target,creator,description
+https://geoconnex.us//usgs/mainstems/([0-9_]+).*$, https://hydro.nationalmap.gov/arcgis/rest/services/3DHP_all/MapServer/1/query?where=mainstemid%3D'https%3A%2F%2Fgeoconnex.us%2Fusgs%2Fmainstems%2F$1'&outFields=*&f=geojson&inSR=4269&outSR=4326, dblodgett@usgs.gov, USGS Mainstem ID