Matsya Purana — Rite and Layout for Consecrating Ponds
महानदीजलोपेतां दध्यक्षतसमन्विताम् उत्तराभिमुखीं धेनुं जलमध्ये तु कारयेत् //
mahānadījalopetāṃ dadhyakṣatasamanvitām uttarābhimukhīṃ dhenuṃ jalamadhye tu kārayet //
He should place a milch-cow in the midst of the water, furnished with the water of a great river and accompanied by curds (dadhi) and unbroken rice-grains (akṣata), with the cow facing north.
This verse is not about Pralaya; it prescribes a ritual procedure (vidhi) involving a cow, river-water, and auspicious offerings like curds and akṣata.
It aligns with dāna and ritual obligations: a householder (and by extension a king as patron of dharma) is instructed to perform regulated offerings using auspicious substances and correct orientation to accrue religious merit and uphold social-religious order.
Ritually, it specifies (1) the medium: great river-water, (2) the offerings: curds and akṣata, (3) the spatial placement: midstream/in the water, and (4) the directional rule: the cow must face north—typical of precise procedural injunctions in Purāṇic rites.