KOD: 〔湿原の泥炭地(でいたんち)にできる小さい池や沼〕 a pond in a peat bog.

Shinsen: 〘文章語〙池のつつみ。
Sankoku: 〘地〙泥炭(でいたん)層の湿原(しつげん)にある浅い池。尾瀬(おぜ)などに見られる。
Smk:
㊀池のつつみ。土手。
㊁湿原の泥炭層にできる池。

The linked wikipedia article: 高層湿原が形成される過程において、堆積した泥炭層の隙間が水で涵養された部分ができる。[...] 独特の生物相ができる。

Also wikipedia: 池塘、地塘、池溏
Adding them as [sK] forms since I don't see them in other references
╭─ーー─┬────────┬───────╮
│ 池塘 │ 17.211 │ 89.3% │
│ 地塘 │  1.748 │  9.1% │
│ 池溏 │    325 │  1.7% │
╰─ーー─┴────────┴───────╯

I'm not sure "pond" by itself is a good way to describe a naturally formed water deposit. A pond is usually artificial.


I don't think the "bank of a pond" sense is archaic. Smk has both senses and doesn't tag it in any way, shinsen gives [form] rather than [arch].
Note that the 精選版 edition of nikkoku used by online aggregators like kotobank only lists the first recorded usage, while the unabridged version usually lists multiple usages over time.

@@ -5,0 +6,8 @@
+</k_ele>
+<k_ele>
+<keb>地塘</keb>
+<ke_inf>&sK;</ke_inf>
+</k_ele>
+<k_ele>
+<keb>池溏</keb>
+<ke_inf>&sK;</ke_inf>
@@ -12 +20,2 @@
-<gloss>pond (in an alpine wetland)</gloss>
+<misc>&form;</misc>
+<gloss>bank (of a pond)</gloss>
@@ -16,2 +25,3 @@
-<misc>&arch;</misc>
-<gloss>bank (of a pond)</gloss>
+<field>&geogr;</field>
+<gloss>small lake (in a high moor; oft. with unique biota)</gloss>
+<gloss>natural pond (in peat-rich wetland)</gloss>

https://ja.wikipedia.org/wiki/池塘
https://kotobank.jp/word/池塘-566187#w-566187

daijs, wiki

池塘	17211