Unusual October Rainfall Pushes Rio Grande to Historic Levels Near Alamosa

ALAMOSA, Colo. — A series of rainfall events beginning in late September and continuing through October has brought an unusual amount of moisture to the San Luis Valley and the greater Four Corners region. The resulting rise in the Rio Grande near Alamosa has drawn attention to the river’s history, local flood protection, and the potential effects of high water on surrounding agricultural lands.

According to the National Weather Service, the Rio Grande at Alamosa reached a reported river stage of approximately 9.9 feet, comparable to a previous crest of 9.9 feet recorded on June 5, 1948. The comparison places the current event in historical context, although the gauge reading represents river stage rather than the actual depth of the river.

An Unusual Time of Year for High Water

October typically brings colder temperatures to the San Luis Valley, where freezing conditions are common. This year’s pattern of late-season rainfall has made the timing of the river’s rise particularly noteworthy.

The sequence of rain events, beginning in late September and continuing through October, provides important context for understanding the current conditions. Rainfall totals, river gauge readings, and the timing of successive crests can help explain how the river has responded to the additional moisture.

Alamosa’s History of Flood Protection

Flooding is not new to the Rio Grande corridor. Following past flooding, improvements were made to the levee system along the river through Alamosa during the 1980s.

The levee remains an important part of the community’s flood protection. However, conditions can differ along stretches of the river outside protected areas, including nearby agricultural lands. Current river levels and official flood guidance are important to understanding the risks in those locations.

A Rare Late-Fall Event

In an article published by the Alamosa Citizen, Pat McDermott, a retiree from Colorado Division of Water Resources in the San Luis Valley, described the late-fall flooding as “legendary,” reflecting how unusual the timing of the event is considered to be.

As the Rio Grande continues to respond to recent rainfall and another crest is anticipated, updated gauge readings and local conditions will help clarify the extent and significance of the event.

For residents and agricultural producers in the San Luis Valley, the evolving situation is a reminder of the connection between weather, river levels, and the infrastructure designed to protect communities along the Rio Grande.