WSP04503

• File Number: 8142.600.20
• Description: Trinidad Project - Environmental Studies
• State: CO
• Basin: Arkansas
• Water Division: 2
• Date: 3/1/1974
• Author: Corps of Engineers
• Title: Draft Environmental Statement - Trinidad Lake Project - Purgatoire River - Colorado
• Water Supply Pro - Doc Type: Report/Study

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II. Environmental Setting Without the Project.

A. Features of the Purgatoire River Basin.

1. Geographical Description. The Purgatoire River Basin

extends from the eastern slopes of the Cu1ebra Range of the Sangre

de cristo Mountains in easternmost Costilla County to the city of

Las Animas. The drainage .area is approximately 3,511 square miles

and-occupies parts of Costilla, Las Animas, Otero, and Bent Counties
in Colorado and Colfax and Union Counties in New Mexico. It is
approximately 150 miles long and varies in width from about 10 to
40 miles. Descending generally in a southwest to northeast direction,

the roughly cresent-shaped basin features high mountain peaks, rugged

foothills and extensive high plains. Elevations range from 14,069
feet at Cu1ebra Peak to 4,100 feet at Las Animas at the lowermost
part of the basin.
The basin is drained by the Purgatoire River, a right bank
tributary of the Arkansas River, which, from its formation at the

confluence of the Middle and North Forks, traverses the central

portion of the basin for appro~imately 186 river miles to join the

Arkansas River about 3 miles downstream from Las Animas. The North

and Middle Forks of the Purgatoire River emanate high on the eastern

slopes of the eu1ebra Range. From this mountainous area the river

flows through rough and rocky terrain. Passing through the city of

Trinidad, the river enters a high plains area through which it flow.

in a wide shallow valley for about 35 miles. It then passe. through

a narrow rugged canyon which is about 100 miles long and flanked by

high plains. This canyon gradually widens and merge. with the

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