diff --git a/bld/namelist_files/namelist_defaults_ctsm.xml b/bld/namelist_files/namelist_defaults_ctsm.xml
index 456d99ac2a..fcb9bc2074 100644
--- a/bld/namelist_files/namelist_defaults_ctsm.xml
+++ b/bld/namelist_files/namelist_defaults_ctsm.xml
@@ -498,7 +498,11 @@ attributes from the config_cache.xml file (with keys converted to upper-case).
 <!-- Default surface roughness parameterization                         -->
 <!-- ================================================================== -->
 
+<!-- begin slevis TESTING
 <z0param_method>ZengWang2007</z0param_method>
+<z0param_method phys="clm5_1">Meier2022</z0param_method>
+end slevis TESTING -->
+<z0param_method>Meier2022</z0param_method>
 
 <use_z0m_snowmelt z0param_method="Meier2022" >.true.</use_z0m_snowmelt>
 <use_z0m_snowmelt >.false.</use_z0m_snowmelt>