diff --git a/models/ROMS_rutgers/model_mod.f90 b/models/ROMS_rutgers/model_mod.f90
index 949d28f13..132796b38 100644
--- a/models/ROMS_rutgers/model_mod.f90
+++ b/models/ROMS_rutgers/model_mod.f90
@@ -130,6 +130,7 @@ module model_mod
 integer  :: assimilation_period_seconds  = 0                ! Assimilation window in secs
 real(r8) :: perturbation_amplitude       = 0.02             ! Perturbation size for generating an ensemble
 integer  :: debug                        = 0                ! Turn up for more debug messages
+logical  :: convert_salinity_to_kgkg     = .true.           ! model_interpolate salinity ouput in kg/kg 
 
 character(len=vtablenamelength) ::                &
           variables(MAX_STATE_VARIABLE_FIELDS_CLAMP) = ' '  ! Table of state variables and associated metadata
@@ -140,7 +141,8 @@ module model_mod
                      perturbation_amplitude,      &
                      roms_filename,               &
                      debug,                       &
-                     variables
+                     variables,                   &
+                     convert_salinity_to_kgkg
 
 ! Interpolation grid handles 
 type(quad_interp_handle) :: interp_t_grid, &
@@ -352,6 +354,8 @@ subroutine model_interpolate(state_handle, ens_size, location, qty, expected_obs
 logical     :: on_land              
 
 
+real(r8), parameter :: CONCENTRATION_TO_PPT = 1000.0_r8
+
 type(quad_interp_handle) :: interp
 
 if (.not. module_initialized) call static_init_model
@@ -472,6 +476,8 @@ subroutine model_interpolate(state_handle, ens_size, location, qty, expected_obs
   expected_obs = sensible_temp(expected_T, expected_S, pdbar) 
 endif
 
+if (convert_salinity_to_kgkg .and. qty == QTY_SALINITY) expected_obs = expected_obs / CONCENTRATION_TO_PPT
+
 istatus = 0
 
 end subroutine model_interpolate
diff --git a/models/ROMS_rutgers/readme.rst b/models/ROMS_rutgers/readme.rst
index 6dbe51879..d48c64114 100644
--- a/models/ROMS_rutgers/readme.rst
+++ b/models/ROMS_rutgers/readme.rst
@@ -143,6 +143,10 @@ The table below describes the configurable variables in this namelist:
      - `character(len=vtablenamelength), dimension(MAX_STATE_VARIABLES * table_columns)`
      - `' '` 
      - Specifies the list of ROMS variables to be assimilated. The variable table is parsed as flat strings with metadata.
+   * - ``convert_salinity_to_kgkg``
+     - `logical`
+     - `.true.`
+     - If true, module_interpolate salinity output is converted to kg/kg, otherwise PSU (g/g) is used. Be sure to match observation units.
 
 
 Variables Table Format