diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9fbb31c11..0c310052f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -164,6 +164,7 @@ _Breaking developer changes, which may affect downstream projects or sites that
 * Don't consider traffic_calming features as areas ([id-tagging-schema#1076])
 * Add rendering style for roller coaster tracks and supports ([#9891], thanks [@mangerlahn])
 * Drop `*:wikipedia` tags when switching to a new NSI-based preset which specifies a corresponding `*:wikidata` tag ([#9103])
+* Add rendering style for `waterway=flowline` features: as wide as rivers, but without border and slightly opaque ([#10283])
 
 [#9103]: https://github.com/openstreetmap/iD/issues/9103
 [#9424]: https://github.com/openstreetmap/iD/pull/9424
diff --git a/css/45_waterways.css b/css/45_waterways.css
index 24c83fb71..060172803 100644
--- a/css/45_waterways.css
+++ b/css/45_waterways.css
@@ -67,26 +67,39 @@ path.line.stroke.tag-waterway {
 
 
 /* wide waterways (river) */
-path.line.shadow.tag-waterway-river {
+path.line.shadow.tag-waterway-river,
+path.line.shadow.tag-waterway-flowline {
     stroke-width: 20;
 }
-path.line.casing.tag-waterway-river {
+path.line.casing.tag-waterway-river,
+path.line.casing.tag-waterway-flowline {
     stroke-width: 10;
 }
-path.line.stroke.tag-waterway-river {
+path.line.stroke.tag-waterway-river,
+path.line.stroke.tag-waterway-flowline {
     stroke-width: 8;
 }
 
-.low-zoom path.line.shadow.tag-waterway-river {
+.low-zoom path.line.shadow.tag-waterway-river,
+.low-zoom path.line.shadow.tag-waterway-flowline {
     stroke-width: 16;
 }
-.low-zoom path.line.casing.tag-waterway-river {
+.low-zoom path.line.casing.tag-waterway-river,
+.low-zoom path.line.casing.tag-waterway-flowline {
     stroke-width: 7;
 }
-.low-zoom path.line.stroke.tag-waterway-river {
+.low-zoom path.line.stroke.tag-waterway-river,
+.low-zoom path.line.stroke.tag-waterway-flowline {
     stroke-width: 5;
 }
 
+path.line.stroke.tag-waterway-flowline {
+    stroke-opacity: 0.5;
+}
+path.line.casing.tag-waterway-flowline {
+    display: none;
+}
+
 
 /* ditch */
 .preset-icon .icon.tag-waterway-ditch {