added exception to handle empty ecy_df in 0c.

0c_Create_Streamflow_Observations_v3.ipynb

@@ -652,7 +652,10 @@
     "    NWIS_OWRD_clean = NWIS_OWRD_joined[~NWIS_OWRD_joined.index.duplicated(keep='first')]\n",
     "    \n",
     "    # Merge with ECY\n",
-    "    NWIS_OWRD_ECY_joined = pd.concat([NWIS_OWRD_clean, ecy_df])\n",
+    "    if ecy_df:\n",
+    "        NWIS_OWRD_ECY_joined = pd.concat([NWIS_OWRD_clean, ecy_df])\n",
+    "    else:\n",
+    "        NWIS_OWRD_ECY_joined = NWIS_OWRD_clean\n",
     "    # drop duplicated indexes, keeping the last occurence (ECY occurs last). Only dups now should be ecy\n",
     "    # try following this thing: https://saturncloud.io/blog/how-to-drop-duplicated-index-in-a-pandas-dataframe-a-complete-guide/#:~:text=Pandas%20provides%20the%20drop_duplicates(),names%20to%20the%20subset%20parameter.\n",
     "    NWIS_OWRD_ECY_clean = NWIS_OWRD_ECY_joined[~NWIS_OWRD_ECY_joined.index.duplicated(keep='last')]\n",