108°W 106°W 104°W SEDGWICK Cache la Poudre River LOGAN South Platte River Little Snake River MOFFAT JACKSON LARIMER PHILLIPS Yampa River ROUTT WELD f MORGAN White River GRAND 40°N Blue River BOULDER YUMA 40°N RIO BLANCO WASHINGTON BROOMFIELD EXPLANATION GILPIN ADAMS High Plains DENVER Regional Aquifers Eagle River CLEAR CREEK Region Eagle River SUMMIT GARFIELD EAGLE ARAPAHOE e North Fork South PlatteJEFFERSON River Mountainous Region Outline Colorado River Roaring Fork River Arikaree River Mountainous Region DOUGLAS KIT CARSON Arkansas River Dominated by East Muddy Creek ELBERT PITKIN Precambrian Rocks MESA LAKE PARK Colorado Taylor River Area Where Colorado LINCOLN Plateaus Regional Aquifers Big Sandy Creek Plateaus DELTA d TELLER Extend Into Mountainous c EL PASO Region Region CHAFFEE CHEYENNE GUNNISON Colorado Neogene Volcanics South Arkansas River Piedmont Gunnison River FREMONT Uncompahgre River Paleogene Volcanics MONTROSE Region San Miguel River Arkansas River CROWLEY KIOWA OURAY PUEBLO CUSTER 38°N SAGUACHE SAN MIGUEL 38°N Mountainous Valley Key b BENT PROWERS HINSDALE OTERO Intermountain Valley Outline DOLORES SAN JUAN a a) San Luis Valley West Dolores River Rio Grande MINERAL HUERFANO b) Wet Moutain Valley- Dolores River Huerfano Park RIO GRANDE ALAMOSA c) Upper Arkansas Valley d) South Park MONTEZUMA Los Pinos River BACA Animas River LAS ANIMAS e) Blue River Valley LA PLATA COSTILLA Purgatoire River CONEJOS f) Middle and North Parks Piedra River San Juan RiverARCHULETA 108°W 106°W 104°W 0 20 40 60 80 100 Miles 0 20 40 60 80 100 Kilometers Figure 12-01. Mountainous region. Valley outlines from NHDH HUC8; geology from Tweto (1979). Colorado Geological Survey ON-010 Colorado Groundwater Atlas. .