FLOOD11631 ‎(2)‎

• County: Costilla
• Community: Costilla County
• Stream Name: Rio Grande, Trinchera Creek, Culebra Creek, Costi
• Basin: Rio Grande
• Title: Floodplain Information Report - Costilla County
• Date: 3/1/1989
• Prepared For: Costilla County, CWCB
• Floodplain - Doc Type: Floodplain Report/Masterplan

2.2 Human Settlement
With~n Costilla County there are ~wo incorporated
municipalities, the Towns of San Luis and Blanca, as well as
numerous unincorporated settlemen~s. San Luis is the oldest
town in Colorado, having been incorpo~ated in 1851. The whole
area was settled as part of the northward expansion by Spanish
settlers from the Santa Fe/Taos area of what is now north~rn
New Mexico. They were the first white settlers in the area.
Much evidence of the area's Spanish heritage still remain~.
According to the 1980 U.S. Census, the total population of
Costilla County was 3,071. In May, 1988 the Colorado
Department of Local Affairs estimated the county's 1987
population at 3,403. The 1980 Census population for the Town
of Blanca was 252, and for the Town of San Luis it was 842.
State estimates for 198'7 population for the two towns werP 289
and 954, respectively.
2.3 Studv Reaches
Tn addition to examining the Rio Grande throuqh Costilla
County, this report examines all three major streams that are
tributary to the Rio Grande (Trincher~ Creek, Culebra Creek,
and Costilla Creek), and their subtributaries, from the Sangre
de Cristo Mountains downstream to their confluences with the
Rio Grande (or to the state line in the case of Costilla
Creek). Subtributaries were studied where existing or
projected populatioii concentrations or development activifiy
warranted delineation. While this sCudy was being prepared,
one area of particular interest was t~e site of the proposed
gold mi~ing and milling project by Battle Mountain Corpor~tion,
about 3 miles east of San Luis in the Rito Seco basin.
Specific stream reaches, with approxi~ate lengths, are listed
in Table 1.
2.4 Rio Grande Basin
The Rio Grande has its headwaters in the San Juan Mountains
of Hinsdale, Mineral, and San Juan Counties. Elevations in the
western headwaters range as high as 13,895 feet. (The highest
elevation in the entire Rio Grande basin is actually in
Costilla County, at 14,345 feet.) The river then flows
sou~heasterly into Rio Grande County and then Alamosa County,
whege it tuzns to the south. It enters Costilla County at an
elevation of about 7,520 feet, forming the boundary between
Costilla and Conejos Counties. It leaves Colorado at an
elevation of about 7,475 feet, continuing through Albuquerque
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