diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index 7232bda..282f0ee 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,3 +1,3 @@
 {
-  ".": "1.0.8"
+  ".": "1.0.9"
 }
diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..2bfb363
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,9 @@
+# Changelog
+
+## [1.0.9](https://github.com/HydrologicEngineeringCenter/cwms-python/compare/v1.0.8...v1.0.9) (2026-09-10)
+
+
+### Bug Fixes
+
+* bump requests, black, pytest ([c37a4fe](https://github.com/HydrologicEngineeringCenter/cwms-python/commit/c37a4fef3918d24f09e620750682b46ccf62d346))
+* initialize time series before concurrent chunk writes ([#310](https://github.com/HydrologicEngineeringCenter/cwms-python/issues/310)) ([d78898f](https://github.com/HydrologicEngineeringCenter/cwms-python/commit/d78898fcf573acc7c845d4f3ac735606e712a9a3))