diff --git a/bld/namelist_files/namelist_defaults_cam.xml b/bld/namelist_files/namelist_defaults_cam.xml
index e61320cfbb..16bb399518 100644
--- a/bld/namelist_files/namelist_defaults_cam.xml
+++ b/bld/namelist_files/namelist_defaults_cam.xml
@@ -2084,6 +2084,8 @@
 <xs_coef_file>atm/waccm/phot/effxstex.txt</xs_coef_file>
 <xs_short_file>atm/waccm/phot/xs_short_c221005mm_slh_c250930.nc</xs_short_file>
 <xs_long_file >atm/waccm/phot/temp_prs_GT200nm_c221005mm_slh_c250930.nc</xs_long_file>
+<xs_short_file phys="cam7">atm/waccm/phot/xs_short_c250124mm.nc</xs_short_file>
+<xs_long_file  phys="cam7">atm/waccm/phot/temp_prs_GT200nm_c250124mm.nc</xs_long_file>
 <rsf_file     >atm/waccm/phot/RSF_GT200nm_v3.0_c080811.nc</rsf_file>
 <exo_coldens_file>atm/cam/chem/trop_mozart/phot/exo_coldens.nc</exo_coldens_file>
 
diff --git a/doc/ChangeLog b/doc/ChangeLog
index 7deae2e301..492dd911ce 100644
--- a/doc/ChangeLog
+++ b/doc/ChangeLog
@@ -1,5 +1,79 @@
 ===============================================================
 
+Tag name: cam6_4_171
+Originator(s): fvitt
+Date: 1 May 2026
+One-line Summary: Update chemistry photolysis inputs for CAM7 compsets
+Github PR URL: https://github.com/ESCOMP/CAM/pull/1547
+
+Purpose of changes (include the issue number and title text for each relevant GitHub issue):
+
+  Update input files for photochemistry in CAM7 compsets -- issue #1546
+
+Describe any changes made to build system: N/A
+
+Describe any changes made to the namelist: N/A
+
+List any changes to the defaults for the boundary datasets: N/A
+
+Describe any substantial timing or memory changes: N/A
+
+Code reviewed by: cacraigucar
+
+List all files eliminated: N/A
+
+List all files added and what they do: N/A
+
+List all existing files that have been modified, and describe the changes:
+
+M       bld/namelist_files/namelist_defaults_cam.xml
+ - update namelist defaults for xs_short_file xs_long_file, only for cam7 phys
+
+If there were any failures reported from running test_driver.sh on any test
+platform, and checkin with these failures has been OK'd by the gatekeeper,
+then copy the lines from the td.*.status files for the failed tests to the
+appropriate machine below.  All failed tests must be justified.
+
+derecho/intel/aux_cam:
+  NLFAIL ERC_D_Ln9.mpasa120_mpasa120.FHISTC_LTso.derecho_intel.cam-outfrq9s_mpasa120
+  NLFAIL ERC_D_Ln9.ne30pg3_ne30pg3_mt232.F1850C_LTso.derecho_intel.cam-outfrq9s
+  NLFAIL ERI_D_Ln18.ne30pg3_ne30pg3_mt232.FHISTC_LTso.derecho_intel.cam-outfrq3s_eri
+  NLFAIL ERP_D_Ln9.ne30pg3_ne30pg3_mt232.F1850C_MTso.derecho_intel.cam-outfrq9s
+  NLFAIL ERR_Ln9.ne16pg3_ne16pg3_mt232.FHISTC_LTso.derecho_intel.cam-outfrq9s_bwic
+  NLFAIL SMS_D_Ln9.ne30pg3_ne30pg3_mt232.FHISTC_MTso.derecho_intel.cam-outfrq9s
+  - new photolysis input files, otherwise bit-for-bit
+
+  DIFF ERP_Ld3.ne16pg3_ne16pg3_mg17.FHISTC_WAt1ma.derecho_intel.cam-reduced_hist1d
+  DIFF ERP_Ld3.ne30pg3_ne30pg3_mt232.FHISTC_MTt4s.derecho_intel.cam-outfrq1d_aoa
+  DIFF ERP_Ln9.ne30pg3_ne30pg3_mg17.FHISTC_WAma.derecho_intel.cam-outfrq9s
+  DIFF ERS_Ln9.ne30pg3_ne30pg3_mg17.FHISTC_WXma.derecho_intel.cam-outfrq9s_ctem
+  DIFF SMS_C2_D_Ln9.ne16pg3_ne16pg3_mg17.FHISTC_WXma.derecho_intel.cam-outfrq9s
+  DIFF SMS_D_Ln9.ne30pg3_ne30pg3_mt232.1850C_CAM70%MT%CT4S2_CLM60%SP_CICE%PRES_DOCN%DOM_MOSART_SGLC_SWAV_SESP.derecho_intel.cam-outfrq9s
+  DIFF SMS_D_Ln9_P1280x1.ne30pg3_ne30pg3_mt232.FHISTC_MTt1s.derecho_intel.cam-outfrq9s_Leung_dust
+  - new photolysis input files
+
+derecho/nvhpc/aux_cam:
+  NLFAIL ERS_Ln9.ne30pg3_ne30pg3_mt232.FHISTC_LTso.derecho_nvhpc.cam-outfrq9s_gpu_default
+  - new photolysis input files, otherwise bit-for-bit
+
+izumi/nag/aux_cam:
+  FAIL ERC_D_Ln9.f10_f10_mt232.FHIST_C5.izumi_nag.cam-outfrq3s_subcol COMPARE_base_rest
+  - pre-existing failure -- see https://github.com/ESCOMP/CAM/issues/1514
+
+  NLFAIL ERC_D_Ln9.ne3pg3_ne3pg3_mt232.FHISTC_LTso.izumi_nag.cam-cosp_rad_diags
+  - new photolysis input files, otherwise bit-for-bit
+
+izumi/gnu/aux_cam:
+  NLFAIL ERC_D_Ln9.mpasa480_mpasa480_mt232.FHISTC_LTso.izumi_gnu.cam-outfrq9s_mpasa480
+  NLFAIL ERC_D_Ln9.ne3pg3_ne3pg3_mt232.FHISTC_LTso.izumi_gnu.cam-sat_lcltod
+  NLFAIL SMS_D_Ln3.ne3pg3_ne3pg3_mt232.PC7.izumi_gnu.cam-pc7_ne3pg3
+  - new photolysis input files, otherwise bit-for-bit
+
+Summarize any changes to answers: larger than round-off for cam7 chemistry compsets
+
+===============================================================
+===============================================================
+
 Tag name: cam6_4_170
 Originator(s): fvitt
 Date: 30 Apr 2026