diff --git a/python/ngen_cal/setup.cfg b/python/ngen_cal/setup.cfg
index a5ac0f38..d52f515b 100644
--- a/python/ngen_cal/setup.cfg
+++ b/python/ngen_cal/setup.cfg
@@ -34,6 +34,7 @@ install_requires =
     pydantic<2
     pandas>=1.1.2
     geopandas
+    fiona<1.10.0; python_version < "3.9"
     matplotlib
     hydrotools.metrics
     hydrotools.nwis_client