diff --git a/wip/274-dev.md b/wip/274-dev.md
index 1cd2464..a6e8611 100644
--- a/wip/274-dev.md
+++ b/wip/274-dev.md
@@ -100,13 +100,13 @@ size OSM splits into separate ways.
 
 ### Watercourses the road meets
 
-Cross-checked against the 国土数値情報 河川データセット (W05) via the Geoshape repository
-at 国立情報学研究所, covering the 石狩川, 鵡川 and 沙流川 systems. 30 of 34 names appear in
-both that dataset and OpenStreetMap, and 29 of those agree on position to within 110 m.
+Cross-checked against the 国土数値情報 河川データセット (W05) via the Geoshape repository at
+国立情報学研究所 — all 561 named rivers of the 石狩川, 鵡川 and 沙流川 systems, since named
+rivers each carry their own 河川コード and are not in the 「その他」 group. 34 distinct
+names; 31 appear in both W05 and OpenStreetMap, and of those all but one agree on
+position to within 110 m.
 
-Offset is closest approach; under ~30 m means the road crosses it. Source column: `both`,
-`W05 only` (official but missing from OSM), `OSM only` (in OSM with no official
-counterpart at that position).
+Offset is closest approach; under ~30 m means the road crosses it.
 
 | km | Offset (m) | Watercourse | Water system | Source |
 |--:|--:|---|---|---|
@@ -120,7 +120,7 @@ counterpart at that position).
 | 52.11 | 16 | 夕張川 | 石狩川水系 | both |
 | 53.69 | 16 | ポンクルキ川 | 石狩川水系 | both |
 | 55.14 | 143 | シイタルキ川 | 石狩川水系 | both |
-| 58.26 | 9 | ホルカクルキ川 | — | OSM only |
+| 58.26 | 9 | ホルカクルキ川 | 石狩川水系 | both |
 | 58.56 | 52 | 滝沢川 | 石狩川水系 | both |
 | 59.54 | 58 | 松竹沢川 | 石狩川水系 | both |
 | 63.02 | 8 | 名称不明 | 鵡川水系 | W05 only |
@@ -145,17 +145,25 @@ counterpart at that position).
 | 107.29 | 18 | 滝の沢川 | 沙流川水系 | both |
 | 107.83 | 134 | ルウケシオマナイ川 | 沙流川水系 | both |
 
-Four to treat with care:
+Three to treat with care:
 
-- **名称不明**, 63.02 km, 8 m off. Carried by W05 with no name at all.
-- **デチン沢川**, 102.90 km, in 日高 town. In W05, absent from OSM.
-- **ホルカクルキ川**, 58.26 km in OSM, and route01 calls the valley ホロカクルキ川 —
-  but no such name exists anywhere in W05, whose only クルキ name is ポンクルキ川.
-- **サヌシュッペ川** runs beside the road rather than crossing it once, so the two
-  datasets are tangent 5 km apart (62.46 / 67.62). The crossing is at 大和橋, ~64.4 km.
+- **名称不明**, 63.02 km, 8 m off. W05 carries it with no name at all — the register has
+  a name-shaped hole. Absent from OSM.
+- **デチン沢川**, 102.90 km, in 日高 town. In W05, missing from OSM.
+- **ベリベツ川** is named in both datasets, but the W05 geometry never comes within 300 m
+  of the road while OSM puts it 171 m away at 37.38 km, right at 川端橋.
 
-W05 also carries **ホロカユウパロ川** in the 石狩川 system — the Ainu form behind 夕張,
-as a river name. Not near R274.
+**サヌシュッペ川** is not a disagreement: it runs beside the road rather than crossing it,
+so each dataset is tangent at a different reach (62.46 / 67.62). The crossing is at
+大和橋, around 64.4 km. Any parallel watercourse behaves this way.
+
+**ホルカクルキ川** at 58.26 km is confirmed three ways and agrees to the metre: OSM, W05
+(河川コード 8101030169), and the 北海道 name plate on the bank, which reads 一級河川石狩川水系
+ホルカクルキ川 and gives the Ainu original as **ホロカ・クルヒ (horka・kurihi)** — *horka*
+"to turn back", *kurihi* "its shadow". In Ainu river naming *horka* marks a stream running
+counter to its parent river, so the name records a hydrological fact. The same element
+appears on **ホロカユウパロ川** elsewhere in the 石狩川 system — the Ainu form behind 夕張.
+route01's ホロカクルキ川 is a slip: the writer applied the Ainu form to the Japanese name.
 
 ### PoI, in road order