diff --git a/datastore/datastore/storagebackend/postgresql/common.go b/datastore/datastore/storagebackend/postgresql/common.go
index dc402da1..795e5d17 100644
--- a/datastore/datastore/storagebackend/postgresql/common.go
+++ b/datastore/datastore/storagebackend/postgresql/common.go
@@ -36,8 +36,8 @@ func getTimeFilter(tspec common.TemporalSpec) string {
 	return fmt.Sprintf("(%s)", strings.Join(timeExprs, " AND "))
 }
 
-// createObsQueryVals creates from polygon, circle, filter, and tspec values used for querying
-// observations.
+// createObsQueryVals creates from polygon, circle, camslRange, filter, and tspec values used for
+// querying observations.
 //
 // Values to be used for query placeholders are appended to phVals.
 //
@@ -49,13 +49,13 @@ func getTimeFilter(tspec common.TemporalSpec) string {
 // - nil,
 // otherwise (..., ..., ..., ..., error).
 func createObsQueryVals(
-	polygon *datastore.Polygon, circle *datastore.Circle, filter map[string]*datastore.Strings,
-	tspec common.TemporalSpec, phVals *[]interface{}) (
+	polygon *datastore.Polygon, circle *datastore.Circle, camslRange string,
+	filter map[string]*datastore.Strings, tspec common.TemporalSpec, phVals *[]interface{}) (
 	string, string, string, string, error) {
 
 	timeFilter := getTimeFilter(tspec)
 
-	geoFilter, err := getGeoFilter(polygon, circle, phVals)
+	geoFilter, err := getGeoFilter(polygon, circle, camslRange, phVals)
 	if err != nil {
 		return "", "", "", "", fmt.Errorf("getGeoFilter() failed: %v", err)
 	}
@@ -70,8 +70,15 @@ func createObsQueryVals(
 		}
 	}
 
-	int64MdataFilter := getInt64MdataFilter(filter, phVals)
-	stringMdataFilter := getStringMdataFilter(filter, phVals)
+	int64MdataFilter, err := getInt64MdataFilter(filter, phVals)
+	if err != nil {
+		return "", "", "", "", fmt.Errorf("getInt64MdataFilter() failed: %v", err)
+	}
+
+	stringMdataFilter, err := getStringMdataFilter(filter, phVals)
+	if err != nil {
+		return "", "", "", "", fmt.Errorf("getStringMdataFilter() failed: %v", err)
+	}
 
 	// --- END filters for reflectable metadata (of type int64 or string) -------------
 
diff --git a/datastore/datastore/storagebackend/postgresql/getlocations.go b/datastore/datastore/storagebackend/postgresql/getlocations.go
index b9ff677e..2111211e 100644
--- a/datastore/datastore/storagebackend/postgresql/getlocations.go
+++ b/datastore/datastore/storagebackend/postgresql/getlocations.go
@@ -26,10 +26,9 @@ func getLocs(
 
 	// get values needed for query
 	phVals := []interface{}{} // placeholder values
-	timeFilter, geoFilter, int64MdataFilter, stringMdataFilter,
-		err := createObsQueryVals(
-		request.GetSpatialPolygon(), request.GetSpatialCircle(), request.GetFilter(), tspec,
-		&phVals)
+	timeFilter, geoFilter, int64MdataFilter, stringMdataFilter, err := createObsQueryVals(
+		request.GetSpatialPolygon(), request.GetSpatialCircle(), request.GetCamslRange(),
+		request.GetFilter(), tspec, &phVals)
 	if err != nil {
 		return nil, fmt.Errorf("createLocsQueryVals() failed: %v", err)
 	}
diff --git a/datastore/datastore/storagebackend/postgresql/getobservations.go b/datastore/datastore/storagebackend/postgresql/getobservations.go
index 43527b35..56258da8 100644
--- a/datastore/datastore/storagebackend/postgresql/getobservations.go
+++ b/datastore/datastore/storagebackend/postgresql/getobservations.go
@@ -209,8 +209,8 @@ type filterInfo struct {
 
 // TODO: add filter info for non-reflectable types
 
-// getPolygonFilter derives the expression used in a WHERE clause for selecting only
-// points inside a polygon.
+// getPolygonFilter derives the expression used in a WHERE clause for selecting only points inside
+// a polygon.
 //
 // Values to be used for query placeholders are appended to phVals.
 //
@@ -253,8 +253,8 @@ func getPolygonFilter(polygon *datastore.Polygon, phVals *[]interface{}) (string
 	return whereExpr, nil
 }
 
-// getCircleFilter derives the expression used in a WHERE clause for selecting only
-// points inside a circle.
+// getCircleFilter derives the expression used in a WHERE clause for selecting only points inside
+// a circle.
 //
 // Values to be used for query placeholders are appended to phVals.
 //
@@ -291,14 +291,34 @@ func getCircleFilter(circle *datastore.Circle, phVals *[]interface{}) (string, e
 	return whereExpr, nil
 }
 
-// getGeoFilter derives from polygon and circle the expression used in a WHERE clause for keeping
-// observations inside both of these areas (i.e. in their intersection).
+// getCamslRangeFilter derives the expression used in a WHERE clause for selecting only points
+// within a camsl range.
+//
+// Values to be used for query placeholders are appended to phVals.
+//
+// Returns (expression, nil) upon success, otherwise (..., error).
+func getCamslRangeFilter(camslRange string, phVals *[]interface{}) (string, error) {
+
+	whereExpr := []string{}
+
+	addWhereCondMatchAnyPatternForInt64("camsl", []string{camslRange}, &whereExpr, phVals, false)
+
+	if len(whereExpr) == 0 {
+		return "TRUE", nil
+	}
+	// assert len(whereExpr) == 1
+	return whereExpr[0], nil
+}
+
+// getGeoFilter derives from polygon, circle, and camslRange the expression used in a WHERE clause
+// for keeping observations inside these areas/ranges (i.e. in their intersection).
 //
 // Values to be used for query placeholders are appended to phVals.
 //
 // Returns (expression, nil) upon success, otherwise (..., error).
 func getGeoFilter(
-	polygon *datastore.Polygon, circle *datastore.Circle, phVals *[]interface{}) (string, error) {
+	polygon *datastore.Polygon, circle *datastore.Circle,
+	camslRange string, phVals *[]interface{}) (string, error) {
 
 	var err error
 
@@ -312,7 +332,12 @@ func getGeoFilter(
 		return "", fmt.Errorf("getCircleFilter() failed: %v", err)
 	}
 
-	return fmt.Sprintf("(%s) AND (%s)", polygonExpr, circleExpr), nil
+	camslRangeExpr, err := getCamslRangeFilter(camslRange, phVals)
+	if err != nil {
+		return "", fmt.Errorf("getCamslRangeFilter() failed: %v", err)
+	}
+
+	return fmt.Sprintf("(%s) AND (%s) AND (%s)", polygonExpr, circleExpr, camslRangeExpr), nil
 }
 
 // scanObsRow scans all columns from the current result row in rows and converts to an ObsMetadata
@@ -320,20 +345,22 @@ func getGeoFilter(
 // Returns (ObsMetadata object, time series ID, nil) upon success, otherwise (..., ..., error).
 func scanObsRow(rows *sql.Rows) (*datastore.ObsMetadata, int64, error) {
 	var (
-		tsID            int64
-		obsTimeInstant0 time.Time
-		pubTime0        sql.NullTime
-		value           sql.NullString
-		point           postgis.PointS
+		tsID           int64
+		obsTimeInstant time.Time
+		pubTime        sql.NullTime
+		value          sql.NullString
+		point          postgis.PointS
+		camsl          sql.NullInt32
 	)
 
 	// initialize colValPtrs with non-reflectable metadata
 	colValPtrs := []interface{}{
 		&tsID,
-		&obsTimeInstant0,
-		&pubTime0,
+		&obsTimeInstant,
+		&pubTime,
 		&value,
 		&point,
+		&camsl,
 	}
 
 	// extend colValPtrs with reflectable metadata of type int64
@@ -362,12 +389,15 @@ func scanObsRow(rows *sql.Rows) (*datastore.ObsMetadata, int64, error) {
 			},
 		},
 		Obstime: &datastore.ObsMetadata_ObstimeInstant{
-			ObstimeInstant: timestamppb.New(obsTimeInstant0),
+			ObstimeInstant: timestamppb.New(obsTimeInstant),
 		},
 		Value: value.String,
 	}
-	if pubTime0.Valid {
-		obsMdata.Pubtime = timestamppb.New(pubTime0.Time)
+	if pubTime.Valid {
+		obsMdata.Pubtime = timestamppb.New(pubTime.Time)
+	}
+	if camsl.Valid {
+		obsMdata.Camsl = &camsl.Int32
 	}
 
 	var err error
@@ -444,8 +474,8 @@ func getObs(
 	// get values needed for query
 	phVals := []interface{}{} // placeholder values
 	timeFilter, geoFilter, int64MdataFilter, stringMdataFilter, err := createObsQueryVals(
-		request.GetSpatialPolygon(), request.GetSpatialCircle(), request.GetFilter(), tspec,
-		&phVals)
+		request.GetSpatialPolygon(), request.GetSpatialCircle(), request.GetCamslRange(),
+		request.GetFilter(), tspec, &phVals)
 	if err != nil {
 		return nil, fmt.Errorf("createObsQueryVals() failed: %v", err)
 	}
@@ -471,6 +501,7 @@ func getObs(
 			%s,
 			point,
 			%s,
+			%s,
 			%s
 		FROM observation
 		JOIN time_series on observation.ts_id = time_series.id
@@ -481,6 +512,7 @@ func getObs(
 		distinctSpec,
 		convertSelectCol(incFields, "pubtime", "observation."),
 		convertSelectCol(incFields, "value", "observation."),
+		convertSelectCol(incFields, "camsl", "observation."),
 		strings.Join(convOI64MC, ","),
 		strings.Join(convOSMC, ","),
 		timeFilter,
diff --git a/datastore/datastore/storagebackend/postgresql/init.go b/datastore/datastore/storagebackend/postgresql/init.go
index 98285e8c..e85b22a3 100644
--- a/datastore/datastore/storagebackend/postgresql/init.go
+++ b/datastore/datastore/storagebackend/postgresql/init.go
@@ -267,6 +267,7 @@ func init() { // automatically called once on program startup (on first import o
 		supIncRespFields.Set(strings.TrimPrefix(f, "observation."))
 	}
 	supIncRespFields.Set("geo_point")
+	supIncRespFields.Set("camsl")
 	supIncRespFields.Set("obstime_instant")
 	supIncRespFields.Set("pubtime")
 	supIncRespFields.Set("value")
diff --git a/datastore/datastore/storagebackend/postgresql/postgresql.go b/datastore/datastore/storagebackend/postgresql/postgresql.go
index 0ae702ff..7aeea3c0 100644
--- a/datastore/datastore/storagebackend/postgresql/postgresql.go
+++ b/datastore/datastore/storagebackend/postgresql/postgresql.go
@@ -5,12 +5,13 @@ import (
 	"datastore/common"
 	"datastore/datastore"
 	"fmt"
-	_ "github.com/lib/pq"
 	"log"
 	"regexp"
 	"strconv"
 	"strings"
 	"time"
+
+	_ "github.com/lib/pq"
 )
 
 // PostgreSQL is an implementation of the StorageBackend interface that
@@ -192,20 +193,6 @@ func getTSColNamesUniqueCompl() []string {
 	return result
 }
 
-// createPlaceholders returns the list of n placeholder strings for
-// values in a parameterized query, e.g. $1, to_timestamp($2), ..., $n.
-// Items in formats must be strings containing exactly one "$%d" pattern,
-// e.g. "$%d", "to_timestamp($%d)" etc.
-func createPlaceholders(formats []string) []string {
-	phs := []string{}
-	for i, format := range formats {
-		index := i + 1
-		ph := fmt.Sprintf(format, index)
-		phs = append(phs, ph)
-	}
-	return phs
-}
-
 // createSetFilter creates expression used in a WHERE clause for testing
 // if the value in column colName is included in a set of string values.
 // The filter is fully closed (--> return FALSE) if the set non-nil but empty.
@@ -220,16 +207,24 @@ func createSetFilter(colName string, vals []string) string {
 
 // addWhereCondMatchAnyPatternForInt64 appends to whereExpr an expression of the form
 // "(cond1 OR cond2 OR ... OR condN)" where condi tests if the ith pattern in patterns matches
-// colName assumed to be of type int64/BIGINT. A pattern of the form <int64>/<int64> generates
-// a range filter directly on the int type where the from and to values are appended to phVals.
-// Otherwise the function generates an expression where the pattern is matched agains a text-version
-// of the int type in a case-insensitive way. In this case an asterisk in a pattern matches zero or
-// more arbitrary characters, and patterns with '*' replaced with '%' are appended to phVals.
+// colName assumed to be of integer type. A pattern of the form lo/hi, ../hi, lo/.., or ../..
+// generates a range filter directly on the int type where the integer lo and hi values are
+// appended to phVals as appropriate, and the function returns nil.
+//
+// If none of the four patterns matched, there are two cases:
+//
+// Case 1: allowStringMatchFallback is true => the function generates an expression where the
+// pattern is matched against a text-version of the int type in a case-insensitive way. In this
+// case an asterisk in a pattern matches zero or more arbitrary characters, patterns with '*'
+// replaced with '%' are appended to phVals, and the function returns nil.
+//
+// Case 2: allowStringMatchFallback is false => the function returns error.
 func addWhereCondMatchAnyPatternForInt64(
-	colName string, patterns []string, whereExpr *[]string, phVals *[]interface{}) {
+	colName string, patterns []string, whereExpr *[]string, phVals *[]interface{},
+	allowStringMatchFallback bool) error {
 
 	if (patterns == nil) || (len(patterns) == 0) {
-		return // nothing to do
+		return nil // nothing to do
 	}
 
 	// getInt64RangeBoth checks if ptn is of the form '<int64>/<int64>', in which case
@@ -319,15 +314,20 @@ func addWhereCondMatchAnyPatternForInt64(
 			// disable int range filtering, but note that we still don't want to fall
 			// back to regular string matching!
 			whereExprOR = append(whereExprOR, "TRUE")
-		} else { // fall back to regular string matching
+		} else if allowStringMatchFallback { // fall back to regular string matching
 			index++
 			expr := fmt.Sprintf("(lower(%s::text) LIKE lower($%d))", colName, index)
 			whereExprOR = append(whereExprOR, expr)
 			*phVals = append(*phVals, strings.ReplaceAll(ptn, "*", "%"))
+		} else {
+			return fmt.Errorf(
+				"invalid int range pattern: %s; must be one of lo/hi, ../hi, lo/.., or ../..", ptn)
 		}
 	}
 
 	*whereExpr = append(*whereExpr, fmt.Sprintf("(%s)", strings.Join(whereExprOR, " OR ")))
+
+	return nil
 }
 
 // addWhereCondMatchAnyPatternForString appends to whereExpr an expression of the form
@@ -336,10 +336,10 @@ func addWhereCondMatchAnyPatternForInt64(
 // pattern matches zero or more arbitrary characters. The patterns with '*' replaced with '%' are
 // appended to phVals.
 func addWhereCondMatchAnyPatternForString(
-	colName string, patterns []string, whereExpr *[]string, phVals *[]interface{}) {
+	colName string, patterns []string, whereExpr *[]string, phVals *[]interface{}, _ bool) error {
 
 	if (patterns == nil) || (len(patterns) == 0) {
-		return
+		return nil
 	}
 
 	whereExprOR := []string{}
@@ -353,6 +353,8 @@ func addWhereCondMatchAnyPatternForString(
 	}
 
 	*whereExpr = append(*whereExpr, fmt.Sprintf("(%s)", strings.Join(whereExprOR, " OR ")))
+
+	return nil
 }
 
 // getInt64MdataFilterFromFilterInfos derives from filterInfos the expression used in a WHERE
@@ -369,15 +371,20 @@ func addWhereCondMatchAnyPatternForString(
 //
 // Values to be used for query placeholders are appended to phVals.
 //
-// Returns expression.
+// Returns (expression, nil) on success, otherwise (..., error).
 func getMdataFilterFromFilterInfos(
 	filterInfos []filterInfo, phVals *[]interface{},
-	whereExprGenerator func(string, []string, *[]string, *[]interface{})) string {
+	whereExprGenerator func(string, []string, *[]string, *[]interface{}, bool) error,
+	allowStringMatchFallback bool) (string, error) {
 
 	whereExprAND := []string{}
 
 	for _, sfi := range filterInfos {
-		whereExprGenerator(sfi.colName, sfi.patterns, &whereExprAND, phVals)
+		if err := whereExprGenerator(
+			sfi.colName, sfi.patterns, &whereExprAND, phVals,
+			allowStringMatchFallback); err != nil {
+			return "", fmt.Errorf("whereExprGenerator() failed: %v", err)
+		}
 	}
 
 	whereExpr := "TRUE" // by default, don't filter
@@ -385,7 +392,7 @@ func getMdataFilterFromFilterInfos(
 		whereExpr = fmt.Sprintf("(%s)", strings.Join(whereExprAND, " AND "))
 	}
 
-	return whereExpr
+	return whereExpr, nil
 }
 
 // getMdataFilter creates from 'filter' the metadata filter used for querying observations or
@@ -394,11 +401,13 @@ func getMdataFilterFromFilterInfos(
 // pbType2table defines field->table mapping for the type in question.
 // whereExprGenerator defines the expression at the lowest level for the type in question.
 //
-// Returns a metadata filter for a 'WHERE ... AND ...' clause (possibly just 'TRUE').
+// Returns ((a metadata filter for a 'WHERE ... AND ...' clause (possibly just 'TRUE')), nil)
+// on success, otherwise (..., error).
 func getMdataFilter(
 	filter map[string]*datastore.Strings, phVals *[]interface{},
 	pbType2table map[string]string,
-	whereExprGenerator func(string, []string, *[]string, *[]interface{})) string {
+	whereExprGenerator func(string, []string, *[]string, *[]interface{}, bool) error,
+	allowStringMatchFallback bool) (string, error) {
 
 	filterInfos := []filterInfo{}
 
@@ -415,17 +424,26 @@ func getMdataFilter(
 		}
 	}
 
-	return getMdataFilterFromFilterInfos(filterInfos, phVals, whereExprGenerator)
+	whereExpr, err := getMdataFilterFromFilterInfos(
+		filterInfos, phVals, whereExprGenerator, allowStringMatchFallback)
+	if err != nil {
+		return "", fmt.Errorf("getMdataFilterFromFilterInfos() failed: %v", err)
+	}
+	return whereExpr, nil
 }
 
 // getInt64MdataFilter is a convenience wrapper around getMdataFilter for type int64.
-func getInt64MdataFilter(filter map[string]*datastore.Strings, phVals *[]interface{}) string {
-	return getMdataFilter(filter, phVals, pbInt642table, addWhereCondMatchAnyPatternForInt64)
+func getInt64MdataFilter(
+	filter map[string]*datastore.Strings, phVals *[]interface{}) (string, error) {
+	return getMdataFilter(
+		filter, phVals, pbInt642table, addWhereCondMatchAnyPatternForInt64, true)
 }
 
 // getStringMdataFilter is a convenience wrapper around getMdataFilter for type string.
-func getStringMdataFilter(filter map[string]*datastore.Strings, phVals *[]interface{}) string {
-	return getMdataFilter(filter, phVals, pbString2table, addWhereCondMatchAnyPatternForString)
+func getStringMdataFilter(
+	filter map[string]*datastore.Strings, phVals *[]interface{}) (string, error) {
+	return getMdataFilter(
+		filter, phVals, pbString2table, addWhereCondMatchAnyPatternForString, true)
 }
 
 // cleanup performs various cleanup tasks, like removing old observations from the database.
diff --git a/datastore/datastore/storagebackend/postgresql/putobservations.examples.sql b/datastore/datastore/storagebackend/postgresql/putobservations.examples.sql
index 1582e581..ffcc92e4 100644
--- a/datastore/datastore/storagebackend/postgresql/putobservations.examples.sql
+++ b/datastore/datastore/storagebackend/postgresql/putobservations.examples.sql
@@ -124,7 +124,6 @@ INSERT INTO observation (ts_id,
                          history,
                          processing_level,
                          quality_code,
-                         camsl,
                          value)
 VALUES ($1,
         to_timestamp($2),
@@ -135,8 +134,7 @@ VALUES ($1,
         $7,
         $8,
         $9,
-        $10,
-        $11),
+        $10),
        ($12,
         to_timestamp($13),
         $14,
@@ -146,8 +144,7 @@ VALUES ($1,
         $18,
         $19,
         $20,
-        $21,
-        $22)
+        $21)
 ON CONFLICT ON CONSTRAINT observation_pkey DO UPDATE
     SET id               = EXCLUDED.id,
         geo_point_id     = EXCLUDED.geo_point_id,
@@ -156,7 +153,6 @@ ON CONFLICT ON CONSTRAINT observation_pkey DO UPDATE
         history          = EXCLUDED.history,
         processing_level = EXCLUDED.processing_level,
         quality_code     = EXCLUDED.quality_code,
-        camsl            = EXCLUDED.camsl,
         value            = EXCLUDED.value
 WHERE observation.id IS DISTINCT FROM EXCLUDED.id
    OR observation.geo_point_id IS DISTINCT FROM EXCLUDED.geo_point_id
@@ -165,4 +161,3 @@ WHERE observation.id IS DISTINCT FROM EXCLUDED.id
    OR observation.history IS DISTINCT FROM EXCLUDED.history
    OR observation.processing_level IS DISTINCT FROM EXCLUDED.processing_level
    OR observation.quality_code IS DISTINCT FROM EXCLUDED.quality_code
-   OR observation.camsl IS DISTINCT FROM EXCLUDED.camsl
diff --git a/datastore/datastore/storagebackend/postgresql/putobservations.go b/datastore/datastore/storagebackend/postgresql/putobservations.go
index 5d7c1c31..0c46bea2 100644
--- a/datastore/datastore/storagebackend/postgresql/putobservations.go
+++ b/datastore/datastore/storagebackend/postgresql/putobservations.go
@@ -5,12 +5,13 @@ import (
 	"datastore/common"
 	"datastore/datastore"
 	"fmt"
-	"github.com/cridenour/go-postgis"
 	"log"
 	"reflect"
 	"slices"
 	"strings"
 
+	"github.com/cridenour/go-postgis"
+
 	"github.com/lib/pq"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/protobuf/types/known/timestamppb"
@@ -294,7 +295,7 @@ func upsertTSs(
 		log.Printf("In upsertTSs(): concurrency issue detected: 'len(tsIDmap)=%v', 'len(mapTScolVals)=%v', "+
 			"retrying db query...", len(tsIDmap), len(mapTScolVals))
 	}
-	return nil, fmt.Errorf("upsertTSs() failed: still concurrency issues afer 3 retries")
+	return nil, fmt.Errorf("still concurrency issues after 3 retries")
 }
 
 // getObsTime extracts the obs time from obsMdata.
@@ -324,8 +325,9 @@ func getObsTime(obsMdata *datastore.ObsMetadata) (*timestamppb.Timestamp, error)
 // --- END a variant of getObsTime that also supports intervals ---------------------------------
 
 type GeoPoint struct {
-	lon float64
-	lat float64
+	lon   float64
+	lat   float64
+	camsl *int32
 }
 
 // getGeoPointIDs returns a map of GeoPoint to ID of the row in table geo_point that matches point,
@@ -337,21 +339,23 @@ func getGeoPointIDs(db *sql.DB, observations []*datastore.Metadata1) (map[GeoPoi
 	phVals := []interface{}{}
 
 	// Collect all unique points
-	// This looks like premature optimisation... but it is not. Postgres will throw error on duplicates in the INSERT
+	// This looks like premature optimisation... but it is not. Postgres will throw error on
+	// duplicates in the INSERT
 	uniquePoints := map[GeoPoint]bool{}
 	for _, obs := range observations {
 		point := obs.GetObsMdata().GetGeoPoint()
-		uniquePoints[GeoPoint{point.Lon, point.Lat}] = true
+		uniquePoints[GeoPoint{point.Lon, point.Lat, obs.GetObsMdata().Camsl}] = true
 	}
 
 	index := 0
 	// Loop over unique points
 	for point := range uniquePoints {
-		valsExpr0 := fmt.Sprintf(`(ST_MakePoint($%d, $%d)::geography)`,
+		valsExpr0 := fmt.Sprintf(`(ST_MakePoint($%d, $%d)::geography, $%d::integer)`,
 			index+1,
 			index+2,
+			index+3,
 		)
-		phVals0 := []interface{}{point.lon, point.lat}
+		phVals0 := []interface{}{point.lon, point.lat, point.camsl}
 
 		valsExpr = append(valsExpr, valsExpr0)
 		phVals = append(phVals, phVals0...)
@@ -366,21 +370,21 @@ func getGeoPointIDs(db *sql.DB, observations []*datastore.Metadata1) (map[GeoPoi
 	cmd := fmt.Sprintf(`
 	WITH input_rows AS (
 		SELECT * FROM (
-			(SELECT point FROM geo_point LIMIT 0)  -- only copies column names and types
+			(SELECT point, camsl FROM geo_point LIMIT 0)  -- only copies column names and types
 			UNION ALL
 			VALUES %s
-		) t ORDER BY point  -- ORDER BY for consistent order to avoid deadlocks
+		) t ORDER BY point, camsl  -- ORDER BY for consistent order to avoid deadlocks
 	)
    , ins AS (
-		INSERT INTO geo_point (point)
+		INSERT INTO geo_point (point, camsl)
 			SELECT * FROM input_rows
-			ON CONFLICT (point) DO NOTHING
-			RETURNING id, point
+			ON CONFLICT (point, camsl) DO NOTHING
+			RETURNING id, point, camsl
 	)
-	SELECT id, point FROM ins
+	SELECT id, point, camsl FROM ins
 	UNION
-	SELECT c.id, point FROM input_rows
-	JOIN geo_point c USING (point)
+	SELECT c.id, point, camsl FROM input_rows
+	JOIN geo_point c USING (point, camsl)
 	`, strings.Join(valsExpr, ","))
 
 	for range 3 { // try at most 3 times
@@ -395,15 +399,20 @@ func getGeoPointIDs(db *sql.DB, observations []*datastore.Metadata1) (map[GeoPoi
 					log.Printf("db.Query() failed: HINT: %v", e.Hint)
 				}
 			}
-			return nil, fmt.Errorf("tx.Query() failed: %v", err)
+			return nil, fmt.Errorf("db.Query() failed: %v", err)
 		}
 
 		gpIDmap := map[GeoPoint]int64{}
 		var id int64
-		var p postgis.PointS
+		var point postgis.PointS
+		var camsl0 sql.NullInt32
 		for rows.Next() {
-			rows.Scan(&id, &p)
-			gpIDmap[GeoPoint{p.X, p.Y}] = id
+			rows.Scan(&id, &point, &camsl0)
+			var camsl *int32 // default nil
+			if camsl0.Valid {
+				camsl = &camsl0.Int32
+			}
+			gpIDmap[GeoPoint{point.X, point.Y, camsl}] = id
 		}
 
 		// Under concurrent load, if another process is adding the same entry, in which case this transaction
@@ -418,12 +427,11 @@ func getGeoPointIDs(db *sql.DB, observations []*datastore.Metadata1) (map[GeoPoi
 		log.Printf("In getGeoPointIDs(): concurrency issue detected: 'len(gpIDmap)=%v', 'len(uniquePoints)=%v', "+
 			"retrying db query...", len(gpIDmap), len(uniquePoints))
 	}
-	return nil, fmt.Errorf("getGeoPointIDs() failed: still concurrency issues afer 3 retries")
+	return nil, fmt.Errorf("still concurrency issues after 3 retries")
 }
 
 // createInsertVals generates from (tsID, obsTimes, gpIDs, and omds) two arrays:
-//   - in valsExpr: the list of arguments to the VALUES clause in the SQL INSERT
-//     statement, and
+//   - in valsExpr: the list of arguments to the VALUES clause in the SQL INSERT statement, and
 //   - in phVals: the total, flat list of all placeholder values.
 func createInsertVals(
 	tsInfos map[int64]tsInfo, valsExpr *[]string, phVals *[]interface{}) {
@@ -433,7 +441,7 @@ func createInsertVals(
 		obsTimes := tsInfo.obsTimes
 		omds := tsInfo.omds
 		gpIDs := tsInfo.gpIDs
-		for i := 0; i < len(*obsTimes); i++ {
+		for i := range *obsTimes {
 			valsExpr0 := fmt.Sprintf(`(
 			$%d,
 			to_timestamp($%d),
@@ -444,7 +452,6 @@ func createInsertVals(
 			$%d,
 			$%d,
 			$%d,
-			$%d,
 			$%d
 			)`,
 				index+1,
@@ -457,7 +464,6 @@ func createInsertVals(
 				index+8,
 				index+9,
 				index+10,
-				index+11,
 			)
 
 			phVals0 := []interface{}{
@@ -470,7 +476,6 @@ func createInsertVals(
 				(*omds)[i].GetHistory(),
 				(*omds)[i].GetProcessingLevel(),
 				(*omds)[i].GetQualityCode(),
-				(*omds)[i].GetCamsl(),
 				(*omds)[i].GetValue(),
 			}
 
@@ -520,7 +525,6 @@ func upsertObs(
 			history,
 			processing_level,
 			quality_code,
-			camsl,
 			value)
 		VALUES %s
 		ON CONFLICT ON CONSTRAINT observation_pkey DO UPDATE
@@ -532,7 +536,6 @@ func upsertObs(
 	 		history = EXCLUDED.history,
 	 		processing_level = EXCLUDED.processing_level,
 			quality_code = EXCLUDED.quality_code,
-			camsl = EXCLUDED.camsl,
 	 		value = EXCLUDED.value
 		WHERE
 		    observation.id IS DISTINCT FROM EXCLUDED.id OR
@@ -541,8 +544,7 @@ func upsertObs(
 			observation.data_id IS DISTINCT FROM EXCLUDED.data_id OR
 			observation.history IS DISTINCT FROM EXCLUDED.history OR
 			observation.processing_level IS DISTINCT FROM EXCLUDED.processing_level OR
-			observation.quality_code IS DISTINCT FROM EXCLUDED.quality_code OR
-			observation.camsl IS DISTINCT FROM EXCLUDED.camsl
+			observation.quality_code IS DISTINCT FROM EXCLUDED.quality_code
 	`, strings.Join(valsExpr, ","))
 
 	_, err := db.Exec(cmd, phVals...)
@@ -627,7 +629,7 @@ func (sbe *PostgreSQL) PutObservations(request *datastore.PutObsRequest) (codes.
 			tsID := tsIDMap[key]
 
 			point := obs.GetObsMdata().GetGeoPoint()
-			gpID := gpIDMap[GeoPoint{point.GetLon(), point.GetLat()}]
+			gpID := gpIDMap[GeoPoint{point.GetLon(), point.GetLat(), obs.GetObsMdata().Camsl}]
 
 			var obsTimes []*timestamppb.Timestamp
 			var gpIDs []int64
diff --git a/datastore/migrate/data/migrations/1747651104_camsl.down.sql b/datastore/migrate/data/migrations/1747651104_camsl.down.sql
index ea394cda..46b08969 100644
--- a/datastore/migrate/data/migrations/1747651104_camsl.down.sql
+++ b/datastore/migrate/data/migrations/1747651104_camsl.down.sql
@@ -1 +1,3 @@
-ALTER TABLE observation DROP COLUMN camsl;
+ALTER TABLE geo_point DROP CONSTRAINT geo_point_point_camsl_key;
+ALTER TABLE geo_point ADD CONSTRAINT geo_point_point_key UNIQUE (point);
+ALTER TABLE geo_point DROP COLUMN camsl;
diff --git a/datastore/migrate/data/migrations/1747651104_camsl.up.sql b/datastore/migrate/data/migrations/1747651104_camsl.up.sql
index 21cef76d..cb3ee8ae 100644
--- a/datastore/migrate/data/migrations/1747651104_camsl.up.sql
+++ b/datastore/migrate/data/migrations/1747651104_camsl.up.sql
@@ -1 +1,9 @@
-ALTER TABLE observation ADD COLUMN camsl BIGINT;
+ALTER TABLE geo_point ADD COLUMN camsl INTEGER;
+
+-- drop UNIQUE constraint of 'point' column
+-- WARNING: we assume that the constraint name is the correct one (it was never explicitly set)
+ALTER TABLE geo_point DROP CONSTRAINT geo_point_point_key;
+
+-- and instead define a UNIQUE constraint on the combination of the 'point' and 'camsl' columns
+-- (note how we name the new constraint explicitly this time!)
+ALTER TABLE geo_point ADD CONSTRAINT geo_point_point_camsl_key UNIQUE NULLS NOT DISTINCT (point, camsl);
diff --git a/protobuf/datastore.proto b/protobuf/datastore.proto
index 2011812b..18db1b6e 100644
--- a/protobuf/datastore.proto
+++ b/protobuf/datastore.proto
@@ -136,25 +136,25 @@ message ObsMetadata {
     Point geo_point = 1 [json_name = "geo_point"];
     Polygon geo_polygon = 2 [json_name = "geo_polygon"];
   }
-  oneof obstime {
-    google.protobuf.Timestamp obstime_instant = 3 [json_name = "obstime_instant"];
-    //TimeInterval obstime_interval = 4 [json_name = "obstime_interval"]; -- unsupported for now
-  }
-  google.protobuf.Timestamp pubtime = 5;
-  // --- END non-reflectable metadata -----------------
-
-  // --- BEGIN reflectable metadata (of type int64 or string)
-  string id = 6;
-  string data_id = 7 [json_name = "data_id"];
-  string history = 8;
-  string processing_level = 9 [json_name = "processing_level"];
-  int64 quality_code = 10 [json_name = "quality_code"];
-  int64 camsl = 11; // centimeters above mean sea level
+  optional int32 camsl = 3; // centimeters above mean sea level
   // Case 1 - stationary data: camsl of the station ground position
   // Case 2 - mobile data: camsl of the sensor itself
   // NOTE: in Case 1, the absolute vertical location of the sensor would be camsl + level where
   //   level is the height above ground (hag) of the sensor. (Typical values for level are the WMO
   //   standard 2m for temperature and 10m for wind.)
+  oneof obstime {
+    google.protobuf.Timestamp obstime_instant = 4 [json_name = "obstime_instant"];
+    //TimeInterval obstime_interval = 5 [json_name = "obstime_interval"]; -- unsupported for now
+  }
+  google.protobuf.Timestamp pubtime = 6;
+  // --- END non-reflectable metadata -----------------
+
+  // --- BEGIN reflectable metadata (of type int64 or string)
+  string id = 7;
+  string data_id = 8 [json_name = "data_id"];
+  string history = 9;
+  string processing_level = 10 [json_name = "processing_level"];
+  int64 quality_code = 11 [json_name = "quality_code"];
   // --- END reflectable metadata -----------------
 
   string value = 12; // obs value (not metadata in a strict sense)
@@ -207,9 +207,25 @@ message GetObsRequest {
 
   // --- END temporal spec ----------------------------------
 
-  // spatial filter
+  // --- BEGIN spatial filter ---------------------------------------------
   Polygon spatial_polygon = 3; // if specified, only observations in this polygon may be returned
   Circle spatial_circle = 4; // if specified, only observations in this circle may be returned
+  string camsl_range = 5; // if specified, only observations within this CAMSL (centimeters above
+  // mean sea level) range may be returned.
+  // Syntax:
+  // (NOTE: lo and hi are both int32)
+  // Case 1 - 'lo/hi': matches all V where lo <= V <= hi.
+  //     Examples that match V = 10: '10/10', '-10/10', '9/10', '10/11'.
+  //
+  // Case 2 - '../hi': matches all V where V <= hi.
+  //     Examples that match V = 10: '../10' and '../11'.
+  //
+  // Case 3 - 'lo/..': matches all V where lo <= V.
+  //     Examples that match V = 10: '10/..', '9/..'.
+  //
+  // Case 4 - '../..': matches any V. NOTE: this is the default behavior and is thus never required
+  //     to be explicitly specified (it is supported for completeness/consistency).
+  // --- END spatial filter ---------------------------------------------
 
   // search wrt. TSMetadata.links
   // TODO - needs special handling
@@ -257,12 +273,12 @@ message GetObsRequest {
   //           default behavior and is thus never required to be explicitly specified (it is
   //           supported for completeness/consistency).
   //
-  //       Case 2.5: If P is not any of the integer interval forms of Case 2.1..4, then the value
+  //       Case 2.5: If P is none of the integer interval forms of Case 2.1..4, then the value
   //           V of F is converted to a string and matched against P just like in Case 1.
   //           Example: for F='level', V='10', the following values for P will match:
   //           '10', '1*', '*0', '*'.
   //
-  map<string, Strings> filter = 5;
+  map<string, Strings> filter = 6;
 
   // --- END filter for reflectable metadata of type int64 or string -------------------------
 
@@ -274,12 +290,13 @@ message GetObsRequest {
   //       'history')
   //     * 'links' (non-reflectable field in TSMedatata)
   //     * 'geo_point' (non-reflectable field in ObsMetadata)
+  //     * 'camsl' (--- '' ---)
   //     * 'obstime_instant' (--- '' ---)
   //     * 'pubtime' (--- '' ---)
   //     * 'value' (non-reflection handleable string field in ObsMetadata)
-  repeated string included_response_fields = 6;
+  repeated string included_response_fields = 7;
 
-  // repeated string excluded_response_fields = 7; // TODO
+  // repeated string excluded_response_fields = 8; // TODO
 }
 
 message GetObsResponse {
@@ -334,7 +351,8 @@ message GetLocsRequest {
   TimeInterval temporal_interval = 1;
   Polygon spatial_polygon = 2;
   Circle spatial_circle = 3;
-  map<string, Strings> filter = 4;
+  string camsl_range = 4;
+  map<string, Strings> filter = 5;
 }
 
 message LocMetadata {