docs: add water quality integration guide - no API key required

- Document EU Bathing Water Quality API (free, no key needed)
- Add EPA Ireland and Marine Institute alternatives
- Provide implementation examples
- Clarify that water quality data is completely free and public

server/EXTERNAL_API_SETUP.md

@@ -133,16 +133,69 @@ These APIs are not fully implemented yet but have placeholder endpoints:
 
 **Purpose:** Water quality monitoring data for Irish beaches and coastal areas.
 
-**Source:** [EPA Ireland Open Data Portal](https://gis.epa.ie/EPAMaps/)
+**Available Data Sources:**
 
-**Status:** Placeholder implementation - returns mock data
-**Cost:** Free (public data)
-**API Key:** Not required
+#### Option A: EU Bathing Water Quality (Recommended)
+- **Source:** European Environment Agency
+- **API:** https://www.eea.europa.eu/data-and-maps/data/bathing-water-directive-status-of-bathing-water
+- **Cost:** Free, no API key required
+- **Coverage:** All EU designated bathing waters including Ireland
+- **Data Format:** CSV/XML downloads or REST API
+- **Update Frequency:** Annual with in-season updates
+- **Documentation:** https://www.eea.europa.eu/help/glossary/eea-glossary/bathing-water
 
-**To Implement:**
-- Research EPA's data access methods (may require web scraping or specific API)
-- Contact EPA for API access if available
-- Alternative: Use EU Bathing Water Quality data
+**How to Access:**
+1. Use EEA's REST API endpoint
+2. Filter by country code "IE" for Ireland
+3. Parse XML/JSON response
+4. No authentication required
+
+**Example Endpoint:**
+```
+https://www.eea.europa.eu/api/EMIS/get_bathing_water_data?country=IE
+```
+
+#### Option B: EPA Ireland GeoPortal
+- **Source:** EPA Ireland
+- **Portal:** https://gis.epa.ie/EPAMaps/
+- **Cost:** Free, no API key required
+- **Method:** Web scraping or manual data download
+- **Data:** Real-time and historical water quality data
+
+**Access Methods:**
+1. **Manual Download:** Download datasets from EPA GeoPortal
+2. **Web Scraping:** Parse EPA maps (requires permission)
+3. **Contact EPA:** Request API access at info@epa.ie
+
+#### Option C: Marine Institute Ireland
+- **Source:** Marine Institute
+- **Portal:** https://data.marine.ie/
+- **Cost:** Free, no API key required
+- **Data:** Marine water quality, oceanographic data
+- **Format:** Various formats including API access
+
+**How to Access:**
+1. Browse datasets at https://data.marine.ie/
+2. Use ERDDAP server for programmatic access
+3. No API key required for public data
+
+#### Option D: Static Database (Simplest)
+- **Method:** Create a database of Irish beaches with latest quality ratings
+- **Source:** Manual entry from EPA/EU reports
+- **Update:** Quarterly or annually
+- **Pros:** Fast, reliable, no external dependencies
+- **Cons:** Requires manual updates
+
+**Recommended Approach:**
+Use **EU Bathing Water Quality API** (Option A) as it's:
+- Free and public
+- No API key required
+- Covers all Irish beaches
+- Regularly updated
+- Easy to integrate
+
+**Status:** Placeholder implementation - needs integration with one of the above sources
+**API Key:** Not required for any option
 
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