Arroyo Buñirigo is a stream in the Atalaya area of Buenos Aires province that flows into the Río de la Plata. The arroyo carries significant historical weight, having served as an active colonial port through which salt arrived from southern Buenos Aires province and La Pampa, and salted meat was exported to the Caribbean and Brazil — a period during which as many as 40 vessels were reportedly moored here at once.

The most critical consideration for paddlers is water depth at and near the mouth. Sediment accumulation is a persistent and serious problem: the Río de la Plata deposits sediment in a north-south direction, building up to the north of the breakwater structures, while prevailing southeast winds contribute additional sand to the south side. The combined effect means that on most days the depth is insufficient even for small motorboats and inflatable craft to pass through. Paddlers should be aware that low water conditions can render the mouth effectively impassable, and conditions vary considerably depending on river levels.

At the mouth, there are partially constructed breakwater structures (escolleras) from an unfinished marina project that was begun several years ago and subsequently stalled. These structures present a navigational consideration and are visible during low-water periods. The intended marina would have served both recreational and commercial purposes, but the works remain incomplete.

Given the chronic shallow-water and sediment issues at the confluence with the Río de la Plata, paddlers planning to transit the mouth should carefully assess water levels before launching, as conditions that allow passage are the exception rather than the norm.