diff --git a/routes/arctic_hydrology.py b/routes/arctic_hydrology.py
index ad9bd216..9427c2d2 100644
--- a/routes/arctic_hydrology.py
+++ b/routes/arctic_hydrology.py
@@ -400,6 +400,10 @@ def package_stats_data(stream_id, ds):
                 if not np.isnan(v)
             }
 
+    # Move the historical model above the rest.
+    historical_data = stats_dict["data"].pop("historical")
+    stats_dict["data"] = {"historical": historical_data, **stats_dict["data"]}
+
     return stats_dict
 
 
@@ -467,6 +471,10 @@ def package_hydrograph_data(stream_id, datasets):
 
                 model_dict[era] = rows
 
+    # Move the historical model above the rest.
+    historical_data = hydrograph_dict["data"].pop("historical")
+    hydrograph_dict["data"] = {"historical": historical_data, **hydrograph_dict["data"]}
+
     return hydrograph_dict
 
 
@@ -823,6 +831,14 @@ def run_get_arctic_hydrology_modeled_climatology(stream_id):
         data_dict = populate_feature_attributes(data_dict, gdf)
         data_dict = prune_nulls_with_max_intensity(data_dict)
 
+        # apply GCM-projected changes to Blaskey climatology if source is "gcm_diff_applied_to_blaskey"
+        # PGW models without a 1990-2021 historical era are silently absent from this source;
+        # they are only available via source=original_gcm.
+        if source == "gcm_diff_applied_to_blaskey":
+            data_dict["data"] = calculate_and_apply_gcm_diffs_to_blaskey_climatology(
+                data_dict["data"]
+            )
+
         if request.args.get("format") == "csv":
             try:
                 return create_csv(
@@ -837,14 +853,6 @@ def run_get_arctic_hydrology_modeled_climatology(stream_id):
             except Exception:
                 return render_template("500/server_error.html"), 500
 
-        # apply GCM-projected changes to Blaskey climatology if source is "gcm_diff_applied_to_blaskey"
-        # PGW models without a 1990-2021 historical era are silently absent from this source;
-        # they are only available via source=original_gcm.
-        if source == "gcm_diff_applied_to_blaskey":
-            data_dict["data"] = calculate_and_apply_gcm_diffs_to_blaskey_climatology(
-                data_dict["data"]
-            )
-
         return jsonify(data_dict)
 
     except Exception as exc:
@@ -966,6 +974,11 @@ def run_get_arctic_hydrology_wt_modeled_climatology(stream_id):
         data_dict = populate_feature_attributes(data_dict, gdf)
         data_dict = prune_nulls_with_max_intensity(data_dict)
 
+        if source == "gcm_diff_applied_to_blaskey":
+            data_dict["data"] = calculate_and_apply_gcm_diffs_to_blaskey_wt_climatology(
+                data_dict["data"]
+            )
+
         if request.args.get("format") == "csv":
             try:
                 return create_csv(
@@ -980,11 +993,6 @@ def run_get_arctic_hydrology_wt_modeled_climatology(stream_id):
             except Exception:
                 return render_template("500/server_error.html"), 500
 
-        if source == "gcm_diff_applied_to_blaskey":
-            data_dict["data"] = calculate_and_apply_gcm_diffs_to_blaskey_wt_climatology(
-                data_dict["data"]
-            )
-
         return jsonify(data_dict)
 
     except Exception as exc: