diff --git a/components/mpas-seaice/bld/build-namelist b/components/mpas-seaice/bld/build-namelist
index a5b691ce0f62..e653d10f65c9 100755
--- a/components/mpas-seaice/bld/build-namelist
+++ b/components/mpas-seaice/bld/build-namelist
@@ -882,6 +882,7 @@ add_default($nl, 'config_rapid_model_critical_Ra');
 add_default($nl, 'config_rapid_mode_aspect_ratio');
 add_default($nl, 'config_slow_mode_drainage_strength');
 add_default($nl, 'config_slow_mode_critical_porosity');
+add_default($nl, 'config_macro_drainage_timescale');
 add_default($nl, 'config_congelation_ice_porosity');
 
 #######################
diff --git a/components/mpas-seaice/bld/build-namelist-section b/components/mpas-seaice/bld/build-namelist-section
index de5db9e589be..4b99123aa2cf 100644
--- a/components/mpas-seaice/bld/build-namelist-section
+++ b/components/mpas-seaice/bld/build-namelist-section
@@ -398,6 +398,7 @@ add_default($nl, 'config_rapid_model_critical_Ra');
 add_default($nl, 'config_rapid_mode_aspect_ratio');
 add_default($nl, 'config_slow_mode_drainage_strength');
 add_default($nl, 'config_slow_mode_critical_porosity');
+add_default($nl, 'config_macro_drainage_timescale');
 add_default($nl, 'config_congelation_ice_porosity');
 
 #######################
diff --git a/components/mpas-seaice/bld/namelist_files/namelist_defaults_mpassi.xml b/components/mpas-seaice/bld/namelist_files/namelist_defaults_mpassi.xml
index 661a8692dbec..52b692571983 100644
--- a/components/mpas-seaice/bld/namelist_files/namelist_defaults_mpassi.xml
+++ b/components/mpas-seaice/bld/namelist_files/namelist_defaults_mpassi.xml
@@ -387,6 +387,7 @@
 <config_rapid_mode_aspect_ratio>1.0</config_rapid_mode_aspect_ratio>
 <config_slow_mode_drainage_strength>-5.0e-8</config_slow_mode_drainage_strength>
 <config_slow_mode_critical_porosity>0.05</config_slow_mode_critical_porosity>
+<config_macro_drainage_timescale>10.</config_macro_drainage_timescale>
 <config_congelation_ice_porosity>0.85</config_congelation_ice_porosity>
 
 <!-- itd -->
diff --git a/components/mpas-seaice/bld/namelist_files/namelist_definition_mpassi.xml b/components/mpas-seaice/bld/namelist_files/namelist_definition_mpassi.xml
index d75c63fffceb..b0d4060ea186 100644
--- a/components/mpas-seaice/bld/namelist_files/namelist_definition_mpassi.xml
+++ b/components/mpas-seaice/bld/namelist_files/namelist_definition_mpassi.xml
@@ -2461,6 +2461,14 @@ Valid values: Any real number between 0 and 1.
 Default: Defined in namelist_defaults.xml
 </entry>
 
+<entry id="config_macro_drainage_timescale" type="real"
+	category="thermodynamics" group="thermodynamics">
+Timescale for macroscopic drainage.
+
+Valid values: Any positive real number.
+Default: Defined in namelist_defaults.xml
+</entry>
+
 <entry id="config_congelation_ice_porosity" type="real"
 	category="thermodynamics" group="thermodynamics">
 Liquid fraction of congelation ice.
diff --git a/components/mpas-seaice/src/Registry.xml b/components/mpas-seaice/src/Registry.xml
index 7543f42a266a..11b481211858 100644
--- a/components/mpas-seaice/src/Registry.xml
+++ b/components/mpas-seaice/src/Registry.xml
@@ -1727,6 +1727,11 @@
 			possible_values="Any real number between 0 and 1."
 			icepack_name="phi_c_slow_mode"
 		/>
+		<nml_option name="config_macro_drainage_timescale" type="real" default_value="10." units="days"
+			description="Timescale for macroscopic drainage."
+			possible_values="Any positive real number."
+			icepack_name="tscale_pnd_drain"
+		/>
 		<nml_option name="config_congelation_ice_porosity" type="real" default_value="0.85" units="unitless"
 			description="Liquid fraction of congelation ice."
 			possible_values="Any real number between 0 and 1."
diff --git a/components/mpas-seaice/src/shared/mpas_seaice_icepack.F b/components/mpas-seaice/src/shared/mpas_seaice_icepack.F
index e3eaa6c1fdc9..941b06c57e18 100644
--- a/components/mpas-seaice/src/shared/mpas_seaice_icepack.F
+++ b/components/mpas-seaice/src/shared/mpas_seaice_icepack.F
@@ -11580,6 +11580,7 @@ subroutine init_icepack_package_configs(domain)
          config_rapid_mode_aspect_ratio, &
          config_slow_mode_drainage_strength, &
          config_slow_mode_critical_porosity, &
+         config_macro_drainage_timescale, &
          config_congelation_ice_porosity, &
 !         config_frazil_ice_porosity, &
 !         config_frazil_salinity_reduction, &
@@ -11775,6 +11776,7 @@ subroutine init_icepack_package_configs(domain)
     call MPAS_pool_get_config(domain % configs, "config_rapid_mode_aspect_ratio", config_rapid_mode_aspect_ratio)
     call MPAS_pool_get_config(domain % configs, "config_slow_mode_drainage_strength", config_slow_mode_drainage_strength)
     call MPAS_pool_get_config(domain % configs, "config_slow_mode_critical_porosity", config_slow_mode_critical_porosity)
+    call MPAS_pool_get_config(domain % configs, "config_macro_drainage_timescale", config_macro_drainage_timescale)
     call MPAS_pool_get_config(domain % configs, "config_congelation_ice_porosity", config_congelation_ice_porosity)
 !    call MPAS_pool_get_config(domain % configs, "config_frazil_ice_porosity", config_frazil_ice_porosity)
 !    call MPAS_pool_get_config(domain % configs, "config_frazil_salinity_reduction", config_frazil_salinity_reduction)
@@ -12206,6 +12208,7 @@ subroutine init_icepack_package_configs(domain)
          dSdt_slow_mode_in       = config_slow_mode_drainage_strength, &
          phi_c_slow_mode_in      = config_slow_mode_critical_porosity, &
          phi_i_mushy_in          = config_congelation_ice_porosity, &
+         tscale_pnd_drain_in     = config_macro_drainage_timescale, &
 !         shortwave_in            = config_shortwave_type, &
          shortwave_in            = tmp_config_shortwave_type, &
          albedo_type_in          = config_albedo_type, &
@@ -12531,6 +12534,10 @@ subroutine init_icepack_package_configs(domain)
     ! liquid fraction porosity cutoff for slow mode
     !phi_c_slow_mode = config_slow_mode_critical_porosity
 
+    ! tscale_pnd_drain:
+    ! Timescale for macroscopic drainage
+    !tscale_pnd_drain = config_macro_drainage_timescale
+
     ! phi_i_mushy:
     ! liquid fraction of congelation ice
     !phi_i_mushy = config_congelation_ice_porosity