Fix malformed discharge data handling to preserve water level data

- Change data parsing logic to make discharge data optional
- Water level data is now saved even when discharge values are malformed (e.g., "***")
- Handle malformed discharge values gracefully with null instead of skipping entire record
- Add specific handling for "***" discharge values from API
- Improve data completeness by not discarding valid water level measurements

Before: Entire station record was skipped if discharge was malformed
After: Water level data is preserved, discharge set to null for malformed values

Example fix:
- wlvalues8: 1.6 (valid) + qvalues8: "***" (malformed)
- Before: No record saved
- After: Record saved with water_level=1.6, discharge=null

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/water_scraper_v3.py

@@ -338,21 +338,39 @@ class EnhancedWaterMonitorScraper:
                                 q_key = f'qvalues{station_num}'
                                 qp_key = f'QPercent{station_num}'
 
-                                # Check if both water level and discharge data exist
+                                # Check if water level data exists (required)
-                                if wl_key in row and q_key in row:
+                                if wl_key in row:
                                     try:
                                         water_level = row[wl_key]
-                                        discharge = row[q_key]
-                                        discharge_percent = row.get(qp_key)
 
-                                        # Skip if values are None or invalid
+                                        # Skip if water level is None or invalid
-                                        if water_level is None or discharge is None:
+                                        if water_level is None:
                                             continue
 
-                                        # Convert to float
+                                        # Convert water level to float (required)
                                         water_level = float(water_level)
-                                        discharge = float(discharge)
+
-                                        discharge_percent = float(discharge_percent) if discharge_percent is not None else None
+                                        # Try to parse discharge data (optional)
+                                        discharge = None
+                                        discharge_percent = None
+
+                                        if q_key in row:
+                                            try:
+                                                discharge_raw = row[q_key]
+                                                if discharge_raw is not None and discharge_raw != "***":
+                                                    discharge = float(discharge_raw)
+
+                                                    # Only parse discharge percent if discharge is valid
+                                                    discharge_percent_raw = row.get(qp_key)
+                                                    if discharge_percent_raw is not None:
+                                                        try:
+                                                            discharge_percent = float(discharge_percent_raw)
+                                                        except (ValueError, TypeError):
+                                                            discharge_percent = None
+                                                else:
+                                                    logger.debug(f"Skipping malformed discharge data for station {station_num}: {discharge_raw}")
+                                            except (ValueError, TypeError) as e:
+                                                logger.debug(f"Could not parse discharge for station {station_num}: {e}")
 
                                         station_info = self.station_mapping.get(str(station_num), {
                                             'code': f'P.{19+station_num}',
@@ -380,7 +398,7 @@ class EnhancedWaterMonitorScraper:
                                         station_count += 1
 
                                     except (ValueError, TypeError) as e:
-                                        logger.warning(f"Could not parse data for station {station_num}: {e}")
+                                        logger.warning(f"Could not parse water level for station {station_num}: {e}")
                                         continue
                             
                             logger.debug(f"Processed {station_count} stations for time {time_str}")