diff --git a/configs/sites/tier1/derecho/mirrors.yaml b/configs/sites/tier1/derecho/mirrors.yaml
index b42871aa0..76e6a150d 100644
--- a/configs/sites/tier1/derecho/mirrors.yaml
+++ b/configs/sites/tier1/derecho/mirrors.yaml
@@ -1,18 +1,2 @@
 mirrors:
-  local-source:
-    fetch:
-      url: file:///glade/work/epicufsrt/contrib/spack-stack/source-cache
-      access_pair:
-      - null
-      - null
-      access_token: null
-      profile: null
-      endpoint_url: null
-    push:
-      url: file:///glade/work/epicufsrt/contrib/spack-stack/source-cache
-      access_pair:
-      - null
-      - null
-      access_token: null
-      profile: null
-      endpoint_url: null
+  local-source: file:///glade/work/epicufsrt/contrib/spack-stack/source-cache
diff --git a/configs/sites/tier1/derecho/modules.yaml b/configs/sites/tier1/derecho/modules.yaml
index 960198ae7..65801706f 100644
--- a/configs/sites/tier1/derecho/modules.yaml
+++ b/configs/sites/tier1/derecho/modules.yaml
@@ -4,5 +4,4 @@ modules:
     - lmod
     lmod:
       include:
-      - cray-mpich
       - python
diff --git a/configs/sites/tier1/derecho/packages.yaml b/configs/sites/tier1/derecho/packages.yaml
index 3542ba3f3..43954addf 100644
--- a/configs/sites/tier1/derecho/packages.yaml
+++ b/configs/sites/tier1/derecho/packages.yaml
@@ -1,16 +1,7 @@
 packages:
 # Modification of common packages
-  all:
-    # Use system zlib instead of spack-built zlib-ng
-    providers:
-      zlib-api:: [zlib]
   zlib-api:
     buildable: False
-  zlib:
-    buildable: False
-    externals:
-    - spec: zlib@1.2.11
-      prefix: /usr
   # Tell esmf that this is not a 'normal' Cray ...
   esmf:
     require:
@@ -119,3 +110,8 @@ packages:
     externals:
     - spec: wget@1.20.3
       prefix: /usr
+  zlib:
+    buildable: False
+    externals:
+    - spec: zlib@1.2.11
+      prefix: /usr
diff --git a/configs/sites/tier1/derecho/packages_gcc-12.4.0.yaml b/configs/sites/tier1/derecho/packages_gcc-12.4.0.yaml
deleted file mode 100644
index 5f81689ca..000000000
--- a/configs/sites/tier1/derecho/packages_gcc-12.4.0.yaml
+++ /dev/null
@@ -1,37 +0,0 @@
-packages:
-  mpi:
-    buildable: False
-    require: cray-mpich@8.1.29
-  cray-mpich:
-    buildable: False
-    externals:
-    - spec: cray-mpich@8.1.29 +wrappers
-      prefix: /opt/cray/pe/mpich/8.1.29/ofi/gnu/12.3
-      modules:
-      - ncarenv/24.12
-      - craype/2.7.31
-      - cray-mpich/8.1.29
-      - libfabric/1.15.2.0
-      - cray-pals/1.2.11
-  gcc:
-    buildable: False
-    externals:
-    - spec: gcc@12.4.0 languages:='c,c++'
-      prefix: /glade/u/apps/casper/24.12/spack/opt/spack/gcc/12.4.0/5b5c
-      modules:
-      - ncarenv/24.12
-      - gcc/12.4.0
-      extra_attributes:
-        compilers:
-          c: /glade/u/apps/casper/24.12/spack/opt/spack/gcc/12.4.0/5b5c/bin/gcc
-          cxx: /glade/u/apps/casper/24.12/spack/opt/spack/gcc/12.4.0/5b5c/bin/g++
-          fortran: /glade/u/apps/casper/24.12/spack/opt/spack/gcc/12.4.0/5b5c/bin/gfortran
-        environment:
-          prepend_path:
-            # For compiling scotch (which requires Intel MPI) with gcc in the oneapi@2024.2.1 unified environment
-            LD_LIBRARY_PATH: '/glade/u/apps/casper/24.12/spack/opt/spack/intel-oneapi-compilers/2024.2.1/gcc/12.4.0/iq3b/compiler/2024.2/lib'
-          set:
-            # https://github.com/JCSDA/spack-stack/issues/957
-            FI_CXI_RX_MATCH_MODE: 'hybrid'
-        extra_rpaths: []
-
diff --git a/configs/sites/tier1/derecho/packages_gcc-12.5.0.yaml b/configs/sites/tier1/derecho/packages_gcc-12.5.0.yaml
deleted file mode 100644
index 0124c8698..000000000
--- a/configs/sites/tier1/derecho/packages_gcc-12.5.0.yaml
+++ /dev/null
@@ -1,37 +0,0 @@
-packages:
-  mpi:
-    buildable: False
-    require: cray-mpich@8.1.32
-  cray-mpich:
-    buildable: False
-    externals:
-    - spec: cray-mpich@8.1.32 +wrappers
-      prefix: /opt/cray/pe/mpich/8.1.32/ofi/gnu/12.3
-      modules:
-      - ncarenv/25.10
-      - craype/2.7.34
-      - cray-mpich/8.1.32
-      - libfabric/1.22.0
-      #- cray-pals/1.2.11
-  gcc:
-    buildable: False
-    externals:
-    - spec: gcc@12.5.0 languages:='c,c++,fortran'
-      prefix: /glade/u/apps/common/25.10/spack/opt/spack/gcc/12.5.0/hsbg
-      modules:
-      - ncarenv/25.10
-      - gcc/12.5.0
-      extra_attributes:
-        compilers:
-          c: /glade/u/apps/common/25.10/spack/opt/spack/gcc/12.5.0/hsbg/bin/gcc
-          cxx: /glade/u/apps/common/25.10/spack/opt/spack/gcc/12.5.0/hsbg/bin/g++
-          fortran: /glade/u/apps/common/25.10/spack/opt/spack/gcc/12.5.0/hsbg/bin/gfortran
-        environment:
-          prepend_path:
-            # For compiling scotch (which requires Intel MPI) with gcc in the oneapi@2024.2.1 unified environment
-            LD_LIBRARY_PATH: /glade/u/apps/common/25.10/spack/opt/spack/intel-oneapi-compilers/2025.2.1/s4f2/compiler/2025.2/lib:/glade/u/apps/common/25.10/spack/opt/spack/intel-oneapi-compilers/2025.2.1/s4f2/compiler/2025.2/lib64
-          set:
-            # https://github.com/JCSDA/spack-stack/issues/957
-            FI_CXI_RX_MATCH_MODE: 'hybrid'
-        extra_rpaths: []
-
diff --git a/configs/sites/tier1/derecho/packages_gcc-13.3.1.yaml b/configs/sites/tier1/derecho/packages_gcc-13.3.1.yaml
new file mode 100644
index 000000000..035e69368
--- /dev/null
+++ b/configs/sites/tier1/derecho/packages_gcc-13.3.1.yaml
@@ -0,0 +1,39 @@
+packages:
+  all:
+    require:
+    - any_of: ['%gcc@=13.3.1']
+      when: '%gcc'
+  mpi:
+    buildable: false
+    require:
+    - cray-mpich@8.1.32
+  gcc:
+    buildable: false
+    externals:
+    - spec: gcc@13.3.1 languages:='c,c++,fortran'
+      prefix: /opt/cray/pe/gcc-native/13
+      modules:
+      - crayenv/25.03
+      - PrgEnv-gnu/8.6.0
+      - gcc-native/13.2
+      extra_attributes:
+        compilers:
+          c: /opt/cray/pe/gcc-native/13/bin/gcc
+          cxx: /opt/cray/pe/gcc-native/13/bin/g++
+          fortran: /opt/cray/pe/gcc-native/13/bin/gfortran
+        environment:
+          set:
+            PE_GCC_EXTERNAL: native
+            # https://github.com/JCSDA/spack-stack/issues/957
+            FI_CXI_RX_MATCH_MODE: hybrid
+  cray-mpich:
+    buildable: false
+    externals:
+    - spec: cray-mpich@8.1.32 +wrappers
+      prefix: /opt/cray/pe/mpich/8.1.32/ofi/gnu/12.3
+      modules:
+      - craype-network-ofi
+      - cray-mpich/8.1.32
+      - libfabric/1.22.0
+      - cray-pals/1.6.1
+
diff --git a/configs/sites/tier1/derecho/packages_oneapi-2025.2.1.yaml b/configs/sites/tier1/derecho/packages_oneapi-2025.2.1.yaml
deleted file mode 100644
index cd094c017..000000000
--- a/configs/sites/tier1/derecho/packages_oneapi-2025.2.1.yaml
+++ /dev/null
@@ -1,65 +0,0 @@
-packages:
-  mpi:
-    buildable: False
-  cray-mpich:
-    buildable: False
-    externals:
-    - spec: cray-mpich@8.1.32 +wrappers
-      prefix: /opt/cray/pe/mpich/8.1.32/ofi/intel/2022.1
-      modules:
-      - ncarenv/25.10
-      - craype/2.7.34
-      - cray-mpich/8.1.32
-      - libfabric/1.22.0
-  intel-oneapi-compilers:
-    buildable: False
-    externals:
-    - spec: intel-oneapi-compilers@2025.2.1
-      prefix: /glade/u/apps/common/25.10/spack/opt/spack/intel-oneapi-compilers/2025.2.1/s4f2
-      modules:
-        - ncarenv/25.10
-        - intel/2025.2.1
-      extra_attributes:
-        compilers:
-          c: /glade/u/apps/common/25.10/spack/opt/spack/intel-oneapi-compilers/2025.2.1/s4f2/compiler/2025.2/bin/icx
-          cxx: /glade/u/apps/common/25.10/spack/opt/spack/intel-oneapi-compilers/2025.2.1/s4f2/compiler/2025.2/bin/icpx
-          fortran: /glade/u/apps/common/25.10/spack/opt/spack/intel-oneapi-compilers/2025.2.1/s4f2/compiler/2025.2/bin/ifx
-        environment:
-          prepend_path:
-            PATH: '/glade/u/apps/common/25.10/spack/opt/spack/gcc/12.5.0/hsbg/bin'
-            CPATH: /glade/u/apps/common/25.10/spack/opt/spack/intel-oneapi-compilers/2025.2.1/s4f2/compiler/2025.2/include
-            LD_LIBRARY_PATH: /glade/u/apps/common/25.10/spack/opt/spack/intel-oneapi-compilers/2025.2.1/s4f2/compiler/2025.2/lib:/glade/u/apps/common/25.10/spack/opt/spack/intel-oneapi-compilers/2025.2.1/s4f2/compiler/2025.2/lib64
-          set:
-            # https://github.com/JCSDA/spack-stack/issues/957
-            FI_CXI_RX_MATCH_MODE: 'hybrid'
-            # https://github.com/JCSDA/spack-stack/issues/1012
-            I_MPI_EXTRA_FILESYSTEM: 'ON'
-        extra_rpaths: []
-  intel-oneapi-mkl:
-    buildable: False
-    externals:
-    - spec: intel-oneapi-mkl@2025.2.0
-      prefix: /glade/u/apps/derecho/25.10/spack/opt/spack/intel-oneapi-mkl/2025.2.0/intel-oneapi-compilers/2025.2.1/fj2q
-      modules:
-      - intel-oneapi-mkl/2025.2.0
-  gcc:
-    buildable: False
-    externals:
-    - spec: gcc@12.5.0 languages:='c,c++'
-      prefix: /glade/u/apps/common/25.10/spack/opt/spack/gcc/12.5.0/hsbg
-      modules:
-      - ncarenv/25.10
-      - gcc/12.5.0
-      extra_attributes:
-        compilers:
-          c: /glade/u/apps/common/25.10/spack/opt/spack/gcc/12.5.0/hsbg/bin/gcc
-          cxx: /glade/u/apps/common/25.10/spack/opt/spack/gcc/12.5.0/hsbg/bin/g++
-          fortran: /glade/u/apps/common/25.10/spack/opt/spack/gcc/12.5.0/hsbg/bin/gfortran
-        environment:
-          prepend_path:
-            # For compiling scotch (which requires Intel MPI) with gcc in the oneapi@2024.2.1 unified environment
-            LD_LIBRARY_PATH: /glade/u/apps/common/25.10/spack/opt/spack/intel-oneapi-compilers/2025.2.1/s4f2/compiler/2025.2/lib:/glade/u/apps/common/25.10/spack/opt/spack/intel-oneapi-compilers/2025.2.1/s4f2/compiler/2025.2/lib64
-          set:
-            # https://github.com/JCSDA/spack-stack/issues/957
-            FI_CXI_RX_MATCH_MODE: 'hybrid'
-        extra_rpaths: []
diff --git a/configs/sites/tier1/derecho/packages_oneapi-2025.3.1.yaml b/configs/sites/tier1/derecho/packages_oneapi-2025.3.1.yaml
new file mode 100644
index 000000000..4c9d3420a
--- /dev/null
+++ b/configs/sites/tier1/derecho/packages_oneapi-2025.3.1.yaml
@@ -0,0 +1,65 @@
+packages:
+  all:
+    require:
+    - any_of: ['%intel-oneapi-compilers@=2025.3.1']
+      when: '%intel-oneapi-compilers'
+    - any_of: ['%gcc@=13.3.1']
+      when: '%gcc'
+  mpi:
+    buildable: false
+    require:
+    - cray-mpich@8.1.32
+  intel-oneapi-compilers:
+    buildable: false
+    externals:
+    - spec: intel-oneapi-compilers@2025.3.1
+      prefix: /glade/work/epicufsrt/contrib/spack-stack/derecho/installs/oneapi-2025.3.1
+      modules:
+        - crayenv/25.03
+        - PrgEnv-intel/8.6.0
+        - intel/2025.3.1
+      extra_attributes:
+        compilers:
+          c: /glade/work/epicufsrt/contrib/spack-stack/derecho/installs/oneapi-2025.3.1/compiler/2025.3/bin/icx
+          cxx: /glade/work/epicufsrt/contrib/spack-stack/derecho/installs/oneapi-2025.3.1/compiler/2025.3/bin/icpx
+          fortran: /glade/work/epicufsrt/contrib/spack-stack/derecho/installs/oneapi-2025.3.1/compiler/2025.3/bin/ifx
+        environment:
+          set:
+            # https://github.com/JCSDA/spack-stack/issues/957
+            FI_CXI_RX_MATCH_MODE: hybrid
+            # https://github.com/JCSDA/spack-stack/issues/1012
+            I_MPI_EXTRA_FILESYSTEM: ON
+  gcc:
+    buildable: false
+    externals:
+    - spec: gcc@13.3.1 languages:='c,c++'
+      prefix: /opt/cray/pe/gcc-native/13
+      modules:
+      - crayenv/25.03
+      - PrgEnv-gnu/8.6.0
+      - gcc-native/13.2
+      extra_attributes:
+        compilers:
+          c: /opt/cray/pe/gcc-native/13/bin/gcc
+          cxx: /opt/cray/pe/gcc-native/13/bin/g++
+          fortran: /opt/cray/pe/gcc-native/13/bin/gfortran
+        environment:
+          set:
+            PE_GCC_EXTERNAL: native
+            # https://github.com/JCSDA/spack-stack/issues/957
+            FI_CXI_RX_MATCH_MODE: hybrid
+  cray-mpich:
+    buildable: false
+    externals:
+    - spec: cray-mpich@8.1.32 +wrappers
+      prefix: /opt/cray/pe/mpich/8.1.32/ofi/intel/2022.1
+      modules:
+      - craype-network-ofi
+      - cray-mpich/8.1.32
+      - libfabric/1.22.0
+      - cray-pals/1.6.1
+  intel-oneapi-mkl:
+    buildable: false
+    externals:
+    - spec: intel-oneapi-mkl@2025.3
+      prefix: /glade/work/epicufsrt/contrib/spack-stack/derecho/installs/oneapi-2025.3.1
diff --git a/configs/sites/tier1/derecho/setup.sh b/configs/sites/tier1/derecho/setup.sh
new file mode 100644
index 000000000..0d307e730
--- /dev/null
+++ b/configs/sites/tier1/derecho/setup.sh
@@ -0,0 +1,3 @@
+module --force purge
+module use /opt/cray/pe/modulefiles
+module use /glade/work/epicufsrt/contrib/spack-stack/derecho/installs/oneapi-2025.3.1/modulefiles
diff --git a/setup.sh b/setup.sh
index e88fda426..3fd056781 100755
--- a/setup.sh
+++ b/setup.sh
@@ -7,6 +7,9 @@ case $hostname in
   *acorn.wcoss2*)
     . ${SPACK_STACK_DIR}/configs/sites/tier1/wcoss2/setup.sh
     ;;
+  *derecho*)
+    . ${SPACK_STACK_DIR}/configs/sites/tier1/derecho/setup.sh
+    ;;
 esac
 
 export SPACK_STACK_DIR
diff --git a/spack b/spack
index 45341d881..324bf79a3 160000
--- a/spack
+++ b/spack
@@ -1 +1 @@
-Subproject commit 45341d881fe198be63a8bc7e89929355b2b3bba0
+Subproject commit 324bf79a31704dbc68fafc9e4a053aa4c60019ea