Great Sand Dunes National Park and Preserve is a U.S. national park that protects large sand dunes on the eastern edge of the San Luis Valley and a nearby national preserve in the Sangre de Cristo Range in south-central Colorado. The park was first created as Great Sand Dunes National Monument on March 17, 1932, by President Herbert Hoover. At that time, the protected area covered 35,528 acres (55.5 square miles; 143.8 square kilometers). In 2000, the boundaries were changed, and the area was reclassified as a national park and preserve. This change was completed on September 24, 2004. The park covers 107,342 acres (167.7 square miles; 434.4 square kilometers), and the preserve adds 41,686 acres (65.1 square miles; 168.7 square kilometers), totaling 149,028 acres (232.9 square miles; 603.1 square kilometers). In 2019, the park had 527,546 visitors.
The park includes the tallest sand dunes in North America, reaching up to 750 feet (230 meters) high. These dunes cover about 30 square miles (78 square kilometers) and are estimated to contain over 1.2 cubic miles (5 billion cubic meters) of sand. Over long periods, sediments from nearby mountains filled the valley. When lakes in the valley dried up, the exposed sand was carried by strong southwest winds toward the Sangre de Cristo Range, forming the dune field over tens of thousands of years. The four main parts of the Great Sand Dunes system are the mountain watershed, the dune field, the sand sheet, and the sabkha. Ecosystems in the mountain watershed include alpine tundra, subalpine forests, montane woodlands, and riparian zones.
Evidence of human presence in the San Luis Valley dates back about 11,000 years. The first known people in the area were the Southern Ute Tribe, and the Apache and Navajo also have cultural ties to the region. In the late 17th century, Diego de Vargas, a Spanish governor, was the first European recorded to enter the San Luis Valley. Later, explorers such as Juan Bautista de Anza, Zebulon Pike, John C. Frémont, and John Gunnison traveled through the area in the 18th and 19th centuries. Settlers began farming, ranching, and mining in the valley in the late 19th century. The park was first created as a national monument in 1932 to protect it from gold mining and a concrete manufacturing business.
To reach the dunes in spring and summer, visitors must walk across Medano Creek, which has its highest water flow from late May to early June. From July to April, the creek is usually only a few inches deep or dry. Hiking is allowed across the dunes, but visitors should be aware that sand temperatures can reach 150°F (66°C) in summer. Popular activities include sandboarding and sandsledding, which require special equipment that can be rented near the park entrance or in Alamosa. Visitors with four-wheel drive vehicles may drive 22 miles (35 kilometers) on an unpaved road to Medano Pass, crossing Medano Creek nine times and traveling through deep sand. Hunting is allowed in the preserve during autumn but is not permitted in the national park. The preserve covers nearly all the mountainous areas north and east of the dune field, up to the ridgeline of the Sangre de Cristo Range.
History
The oldest evidence of humans in the area is about 11,000 years old. Some of the first people to live in the San Luis Valley and the Great Sand Dunes were nomadic hunter-gatherers who relied on mammoth and bison herds for survival. These people lived during the Stone Age and used large stone spears or dart points called Clovis and Folsom points to hunt. They only stayed in the area when hunting and gathering plants was easy, and they left during times of drought or when food was scarce.
When Spanish explorers arrived in the 17th century, modern American Indian tribes already lived in the region. The Ute people called the Great Sand Dunes "Saa waap maa nache," which means "sand that moves." The Jicarilla Apache called the dunes "Sei-anyedi," meaning "it goes up and down." The Navajo people named Blanca Peak, a mountain near the dunes, "Sisnaajini," or "White Shell Mountain." These tribes used the inner layers of bark from ponderosa pine trees for food and medicine. People from Tewa and Tiwa-speaking pueblos near the Rio Grande believed a lake near the dunes was a sacred place where their people emerged into the present world. They called the lake "Sip'ophe," or "Sandy Place Lake," which is thought to be the springs or lakes west of the dunes.
In 1694, Don Diego de Vargas became the first European known to enter the San Luis Valley. However, Spanish herders and hunters from northern New Mexico may have reached the valley as early as 1598. De Vargas and his men hunted a group of 500 bison in the southern part of the valley before returning to Santa Fe. In 1776, Juan Bautista de Anza and his group likely passed near the dunes during a journey back from a raid against the Comanche. At this time, the valley was a travel route for the Comanche, Ute, and Spanish soldiers. The dunes were probably a visible landmark for travelers.
The first written records about the Great Sand Dunes appeared in the journals of Zebulon Pike in 1807. Pike was exploring the area as part of a mission to find the Arkansas and Red Rivers. He reached the site of present-day Pueblo, Colorado, and later crossed the Sangre de Cristos Mountains near the dunes.
In 1848, John C. Frémont was hired to find a railroad route from St. Louis to California. He crossed the Sangre de Cristos Mountains in winter, proving that such a journey was possible. In 1853, Captain John Gunnison and his group crossed the dunes on horseback. Over time, the Rocky Mountains were explored, and treaties were made with Native American tribes, though many were broken. In 1852, Fort Massachusetts was built and later moved to Fort Garland to protect settlers traveling into the valley. Settlers used trails like Medano Pass and Mosca Pass to reach the valley. These trails were later improved into roads. The Mosca Pass Toll Road was built in the 1870s and used for transportation until a flood damaged it in 1911. It was partially rebuilt in the 1930s and 1950s but is now a hiking trail.
The Herard family, after whom Mount Herard is named, established a ranch along Medano Creek in 1875. They used the old Medano Pass Road to travel. The modern unpaved road follows this route and is only open to four-wheel drive vehicles. The Herards raised cattle, horses, and operated a trout hatchery. Other families, like the Trujillo family, also settled near the dunes. Their ranch later became part of the Medano–Zapata Ranch, owned by the Nature Conservancy since 1999. The Trujillo homestead and ruins were declared a National Historic Landmark in 2004. Frank and Virginia Wellington built a cabin and dug an irrigation ditch that now follows Wellington Ditch Trail.
Gold and silver rushes after 1853 brought many miners to the area, and mining businesses still operate today. Small gold discoveries were made near the San Luis Valley. Some people believed the Great Sand Dunes might contain gold, and newspapers in the 1920s estimated its value. A gold mill was built along Medano Creek in 1932, but the operation was not profitable.
Residents of Alamosa and Monte Vista worried that mining or concrete manufacturing might harm the dunes. By the 1920s, the dunes became a source of local pride and a potential tourist attraction. Members of the P.E.O. Sisterhood pushed for national monument status, which was granted in 1932 by President Herbert Hoover. Later efforts in the 1990s led to the expansion of the area into a national park and preserve by 2000–2004.
Geology
The park has the tallest and widest sand dunes in North America. These dunes rise up to 750 feet (229 meters) from the floor of the San Luis Valley, which is located on the western side of the Sangre de Cristo Range. The dunes cover an area of about 30 square miles (78 square kilometers) and contain more than 1.2 cubic miles (5 billion cubic meters) of sand.
The San Luis Valley was formed when the Sangre de Cristo Range was raised due to the movement of large pieces of Earth’s crust. The San Juan Mountains, to the west of the valley, were created by volcanic activity. The valley is located between these two mountain ranges and is about the same size as the state of Connecticut. Over time, sand, rock, and water from melting glaciers and rain filled the valley. Evidence of flash floods, such as larger rocks found along Medano Creek, shows that sudden, heavy rains once carried sediment through the valley.
In 2002, scientists found lakebed deposits on hills in the southern part of the valley. This discovery confirmed that a large lake, named Lake Alamosa after the largest town in the valley, once covered much of the valley floor. Lake Alamosa disappeared when it broke through volcanic rock in the southern part of the valley. The water then flowed through the Rio Grande, likely creating the steep Rio Grande Gorge near Taos, New Mexico. Smaller lakes also existed in the valley, and sand and rock from the San Juan Mountains and Sangre de Cristo Range continued to flow into these lakes. Over time, climate changes reduced the size of these lakes, leaving behind a layer of sand. Remnants of these lakes still exist as wetlands called sabkhas.
After the lakes dried up, wind carried sand from the valley floor toward a low area of the Sangre de Cristo Range. The wind funnels through three mountain passes—Mosca, Medano, and Music Passes—and the sand collects in this natural area. Wind blowing from the valley toward the mountains and wind blowing back toward the valley during storms cause the dunes to grow taller. Two streams, Medano and Sand Creeks, also carry sand from the mountainside into the dune field and back to the valley floor. These streams then disappear into the sand layer, and wind blows the sand back into the dune field. This process helps form barchan and transverse dunes, which contribute to the dunes being the tallest in North America.
Vegetation has grown on the valley floor, reducing the amount of sand that blows into the main dune field. However, smaller parabolic dunes still form in the sand layer and move across grasslands, joining the main dune field. Some of these dunes become covered by plants and stop moving. The dune system remains stable because opposing wind directions balance each other over time. Additionally, the main dune field has a layer of moist sand beneath a thin layer of dry sand. While wind moves the top layer of sand during storms, the moist sand below stays in place.
Scientists believe Lake Alamosa disappeared about 440,000 years ago. The dunes themselves likely formed from sand left behind by smaller lakes that existed later. A new dating method called optically stimulated luminescence (OSL) is being used to study the age of the dunes. This method involves taking sand samples from deep within the dunes and measuring how long the sand has been buried. So far, OSL dating has shown that the oldest sand deposits are from the late Pleistocene epoch, which was during the middle years of the current ice age.
The dunes have dark areas where magnetite, a type of iron oxide, has settled. Magnetite is a magnetic mineral that is heavier than other sand particles. When wind removes the sand above, magnetite remains in place, forming dark patches visible in the dune field.
Geography
Great Sand Dunes National Park and Preserve is located in Saguache and Alamosa Counties, Colorado, near 37.75° north latitude and 105.5° west longitude. The national park is in the San Luis Valley, while the national preserve is to the east, in part of the Sangre de Cristo Range of the Rocky Mountains. Elevations range from about 7,500 feet (2,291 meters) in the valley west of the dunes to over 13,600 feet (4,146 meters) at Tijeras Peak in the preserve.
The dunes cover about 30 square miles (78 square kilometers), but the flat sand sheet around them holds most of the sand, about 90% of the total in the park. To the east, tall, forested mountains over 13,000 feet (4,000 meters) are the most noticeable feature. Other features include snow-fed creeks from the mountains, alpine lakes, and wetlands formed by spring-fed creeks and small lakes in the valley.
The main dune field is about 4 miles (6.4 kilometers) wide and 6 miles (9.7 kilometers) long. A nearby area called the Star Dune Complex adds about 6 square miles (16 square kilometers), totaling 30 square miles (78 square kilometers). Together, the park and preserve cover about 15 miles (24 kilometers) wide and 15 miles (24 kilometers) long. The park itself includes 107,342 acres (167.7 square miles; 434.4 square kilometers), and the preserve adds 41,686 acres (65.1 square miles; 168.7 square kilometers), for a total of 149,028 acres (232.9 square miles; 603.1 square kilometers).
The Rio Grande National Forest is to the north and southeast, while the Sangre de Cristo Range’s forested slopes were renamed the Great Sand Dunes National Preserve. The San Isabel National Forest is east of the preserve beyond the mountain ridge. Private land borders much of the park’s southern edge. The San Luis Lakes State Wildlife Area is near the park’s southwest corner, and the Rio Grande flows through the valley farther south. The Baca National Wildlife Refuge is to the west, and the San Juan Mountains begin at the valley’s western edge. Private land from the Baca Grande subdivision is near the northwest.
The nearest city is Alamosa, about 30 miles (48 kilometers) away by road to the southwest. Nearby towns include Crestone to the north, Mosca and Hooper to the west, Blanca and Fort Garland to the south, and Gardner to the east. Colorado Springs and Denver are a few hours away by car to the northeast. Major roads through the San Luis Valley include U.S. Route 160, which runs east-west just south of the park, and U.S. Route 285, which runs north-south west of the park, parallel to Colorado State Highway 17.
The Great Sand Dunes are in the high desert of the San Luis Valley, about 7,694 feet (2,345 meters) above sea level, just west of the Sangre de Cristo Range. The dunes have a cold, dry climate with hot summers and cold winters. Summer highs average slightly above 80°F (27°C) in July, the warmest month. Winter nights can be extremely cold, with temperatures below freezing. The dunes receive very little rain, about 11.13 inches (283 mm) per year. Despite this, the area is classified as a desert because of high evaporation rates.
Spring weather varies, with some days warm and sunny, others cold and snowy. March is the snowiest month, though temperatures can reach above 50°F (10°C) on some days. In late spring, Medano Creek often has its highest water flow, but snow and wind may still occur. Summer days are warm, with temperatures averaging 75–80°F (24–27°C), but sand surfaces can reach 150°F (66°C) on sunny afternoons. Nights are cool, with temperatures often below 50°F (10°C). Thunderstorms are common in July and August, bringing rain, wind, and lightning. Fall is generally mild, with warm days and cold nights. Occasional storms may bring ice or snow. Winters are cold, with temperatures well below freezing, but the dry air makes the cold feel less intense. Average winter highs are just above freezing, even in January, the coldest month.
Ecology
The Great Sand Dunes system has four main parts: the mountain watershed, the dune field, the sand sheet, and the sabkha. The mountain watershed gets snow and rain that flows into creeks. These creeks move through alpine tundra, lakes, subalpine and montane woodlands, and then reach the dune field. Sand from the valley floor is caught in streams and carried back toward the valley. When creeks flow into the valley floor, the sand is picked up again and moved to the dune field. The movement of water and wind, along with 7% moisture below the dry sand surface, helps the dunes reach great heights.
The dune field has reversing dunes, transverse dunes (also called crescentic or barchan dunes), and star dunes. The sand sheet is the largest part of the system, covering sandy grasslands around three sides of the dune field. About 90% of the sand is in the sand sheet, and the rest is in the dune field. Small parabolic dunes form in the sand sheet and move into the main dune field. Nabkha dunes form near plants. The sabkha is where sand becomes wet from rising groundwater. When water evaporates in late summer, minerals like baking soda harden the sand into a white crust. Sabkha areas are found in western parts of the sand sheet where groundwater meets the surface. Some sabkha wetlands are deep with many plants and animals, while others are shallow and salty.
The park and preserve have hundreds of plant species that live in environments like alpine tundra and wetlands. Trees include aspen, Douglas fir, pinyon pine, ponderosa pine, Rocky Mountain juniper, three-leaf sumac, bristlecone pine, red osier dogwood, and narrow-leaf cottonwood.
Flowering plants include alpine phlox, dwarf clover, alpine forget-me-not, alpine avens, paintbrush flowers, lousewort, blue-purple penstemon, aspen daisy, western paintbrush, elephantella, snow buttercups, scurfpea, Indian ricegrass, blowout grass, prairie sunflower, Rocky Mountain beeplant, rubber rabbitbrush, speargrass, small-flowered sand-verbena, narrowleaf yucca, prickly pear cactus, Rocky Mountain iris, and white water buttercup.
Inland saltgrass is the main grass type near the sabkha wetlands.
Mammals in the area include pika, yellow-bellied marmot, bighorn sheep, black bear, snowshoe hare, Abert's squirrel, gray and red foxes, cougar, coyote, mule deer, water shrew, beaver, porcupine, kangaroo rat, badger, pronghorn, and elk. Over 2,000 bison live on private land within the park, owned by The Nature Conservancy, which is not open to the public.
More than 250 bird species have been found in the park and preserve. Many birds nest in mountains, forests, grasslands, or wetlands during summer. Some birds include brown-capped rosy finch, white-tailed ptarmigan, red-breasted nuthatch, peregrine falcon, mountain bluebird, northern pygmy owl, dusky grouse, hummingbird (four species), western tanager, burrowing owl, bald eagle, golden eagle, sandhill crane, American avocet, and great blue heron.
Reptiles in the park include short-horned lizard, fence lizard, many-lined skink, bullsnake, and garter snake.
Fish in the park’s streams include Rio Grande cutthroat trout, Rio Grande sucker (Catostomus plebeius), and fathead minnow.
Amphibians include tiger salamander, chorus frog, northern leopard frog, spadefoot toad, Great Plains toad, and Woodhouse’s toad.
The park has several insect species that live only there, such as the Great Sand Dunes tiger beetle, a circus beetle (Eleodes hirtipennis), Werner’s (Amblyderus werneri) and Triplehorn’s (Amblyderus triplehorni) ant-like flower beetle, and undescribed species of clown beetle, noctuid moth, and robber fly. Over 1,000 types of arthropods have been found in the park.
Alpine tundra is the highest ecosystem in the park, where trees cannot grow. Wildflowers, pikas, yellow-bellied marmots, ptarmigans, and bighorn sheep live here. The tundra starts at about 11,700 ft (3,600 m) and reaches the highest peaks. At subalpine elevations near the tree line, trees grow twisted and stunted due to wind, snow, ice, short growing seasons, and poor soil. The area between subalpine forests and alpine tundra is a safe place for some animals and birds during storms. Bristlecone and limber pines grow very slowly and can be over 1,000 years old.
Subalpine forests and meadows collect heavy snow in winter and summer rains. This area has the most variety of Rocky Mountain plants and animals. Subalpine forests range from 9,500 ft (2,900 m) to 11,700 ft (3,600 m). Montane forests and woodlands are found at drier foothills from about 8,000 ft (2,400 m) to 9,500 ft (2,900 m). Pinyon-juniper and ponderosa pine woodlands grow on dry slopes, while cottonwood and aspen trees grow in drainages. Cougars hunt mule deer at night. Owls, dusky grouse, turkeys, and bullsnakes live in these drier woodlands.
The riparian zone follows creeks through subalpine and montane areas. Cottonwood and aspen trees, red osier dogwood, and alder grow here, providing shade and habitat for black bears, water shrews, and western tanagers. Rio Grande cutthroat trout live in Medano Creek.
The top layer of the dune field is often dry, but the dunes stay moist all year because of rain. The 7% moisture under the surface allows animals like Ord’s kangaroo rat, Great Sand Dunes tiger beetle, scurfpea, and blowout grass to live there. Many animals visit the dunes from other areas, including elk, pronghorn, bison, coyotes, bobcats, and raptors.
The sand sheet has grasslands and shrublands around the dune field from 7,500 ft (2,300 m) to 8,200 ft
Features
The park protects the tallest sand dunes in North America, along with alpine lakes, tundra, mountain peaks over 13,000 feet (3,962 m) high, mixed conifer forests, grasslands, and wetlands.
Medano Creek, which is on the east side of the dunes, does not have a permanent or stable streambed because new sand falls into the creek. Underwater sand ridges that work like dams form and break down, creating water surges that look like waves. These surges happen about every 20 seconds. In years with a lot of water, the surges can reach up to 20 inches (51 cm) high. The "surge flow" usually happens during the peak flow period from late May to early June each year.
Big Spring Creek is a special creek fed by a spring that comes from an unconfined aquifer. This creates wetlands that support rare plants and animals in an area that is usually dry. The creek was named a National Natural Landmark in 2012.
Recreation
To reach the dunes, visitors must walk across Medano Creek, which is wide and shallow. The creek usually flows past the main dunes parking area from late April to late June, with the highest flow between late May and early June most years. In other months, the creek is often only a few inches deep or has no water. Hiking is allowed throughout the dunes, but the sand can become very hot in the summer, reaching up to 150 °F (66 °C). Sand wheelchairs are available at the visitor center. Sandboards and sand sleds can be rented near the park entrance or in Alamosa, the nearest city.
The Mosca Pass Trail is a 7-mile (11-kilometer) roundtrip hike that follows a small creek through aspen and evergreen forests to Mosca Pass, which is 9,737 feet (2,968 meters) high in the Sangre de Cristo Range. American Indians and early settlers used this path to travel between the San Luis Valley and the Wet Mountain Valley to the east. Trails in the northeastern part of the park lead to alpine lakes in the mountains. A trail to Medano Lake and Mount Herard’s summit is near Medano Pass Road. A trail along Sand Creek leads to Sand Creek Lakes and Music Pass, which is 11,380 feet (3,470 meters) high and offers views of the Upper Sand Creek basin. Spur trails along Sand Creek connect to four alpine lakes that feed the creek and to several peaks over 13,000 feet (4,000 meters) high. The Sand Ramp Trail connects the dune field to the mountains, linking the park’s campground to Medano Pass Road and the base of the Sand Creek Trail. Most grasslands, shrublands, and wetlands in the park have no trails but are open for hiking. The Nature Conservancy’s Medano Ranch can only be visited on guided tours. A fence surrounds the property to keep the Conservancy’s bison herd contained and to mark boundaries.
Medano Pass Road is a 22-mile (35-kilometer) four-wheel drive (4WD) road that starts where the main park road ends. The unpaved road crosses Medano Creek nine times and travels 4 miles (6.4 kilometers) through deep sand. Only street-licensed 4WD vehicles, motorcycles, or bicycles are allowed. Fat tire bikes are recommended by the park service for the deep sandy sections. The road winds along the eastern edge of the dunes, through a forested mountain canyon inside the National Preserve, and over Medano Pass, which is 9,982 feet (3,043 meters) high at the 11.2-mile (18-kilometer) mark. The road continues down into the Wet Mountain Valley and connects to Colorado State Highway 69. Visitors should know that hunting is allowed in the National Preserve during autumn.
Most of the national park and the entire National Preserve allow horseback riding and pack animals. Areas where riding is not allowed include developed spaces like Pinyon Flats campground, picnic areas, and the visitor center, all paved roads, many hiking trails, and the dunes area from the parking lot to the High Dune, which is for walking only. Horse camping in the national park is limited to wilderness areas, with campsites at least 0.25 miles (0.4 kilometers) from roads or trails. Camping is allowed in most parts of the National Preserve and at designated sites along Medano Pass Road, as long as guidelines for minimal impact are followed. Permitted pack animals include horses, mules, burros, donkeys, alpacas, and llamas. Overnight guests at Zapata Ranch can take guided trips into the park; Zapata Partners is the only NPS-licensed provider of horseback riding in the Great Sand Dunes.
The National Preserve next to the national park is also managed by the National Park Service, and seasonal hunting is allowed there. Hunting rules include not chasing wounded animals if they leave the preserve and enter the national park. Mountain lion hunting with dogs is permitted, but unless the dogs have spotted a lion and are actively pursuing it, they must be leashed. Other animals that can be hunted include turkey, bear, bighorn sheep, elk, and mule deer.
Designations
The dunes and surrounding area became a national monument in 1932 after a law was passed. The law was supported by the P.E.O. Sisterhood and local people, and signed by President Herbert Hoover. The original monument covered 35,528 acres (55.5 square miles; 143.8 square kilometers). In the late 1990s, more support led to the area being renamed Great Sand Dunes National Park and Preserve in 2000. The International Union for Conservation of Nature (IUCN) listed the area as a protected landscape (management category V) in 2000, including the national park, preserve, and Baca National Wildlife Refuge nearby.
In 1976, the U.S. Congress created the Great Sand Dunes Wilderness, a protected area of 32,643 acres (51 square miles; 132 square kilometers) within the monument. This is the only wilderness in the U.S. that protects a saltbush-greasewood ecosystem and includes the entire dune field and much of the area west of the dunes. In 1993, Congress also created the Sangre de Cristo Wilderness, covering 219,900 acres (343.6 square miles; 889.9 square kilometers) of mountainous land. Most of this area is managed by the U.S. Forest Service, while the National Park Service manages the part now called a national preserve. Motorized vehicles and ATVs are not allowed in wilderness areas, and ATVs are banned in the national park and preserve. These rules help protect wildlife, like the Great Sand Dunes tiger beetle, from harm caused by human activities. Both wilderness areas exclude roads, such as the paved park road and the unpaved Medano Pass Road. The IUCN has listed the 51-square-mile (132-square-kilometer) dune area on its global wilderness list (management category Ib) since 1976.
In 1999, the Nature Conservancy bought land in the Medano–Zapata Ranch, located west and south of the dunes. Some of this land is within the national park, including a fenced area with a bison herd in 44,000 acres (68.8 square miles; 178.1 square kilometers). This area can only be visited on guided tours. The Nature Conservancy, along with federal and state governments, aims to protect the ecosystem while allowing sustainable use, similar to conservation plans for parts of the Yukon in Canada.
The redesignation as Great Sand Dunes National Park and Preserve was approved in 2000 when President Bill Clinton signed the Great Sand Dunes National Park and Preserve Act. The law required the Secretary of the Interior to create the park once enough land was acquired. The park and preserve became official in September 2004 after enough land was obtained, making the area four times larger.
In 2002, the Nature Conservancy bought the Baca Ranch, a 97,000-acre (151.6 square mile; 392.5 square kilometer) area, for $31.28 million. Funding came from the Department of the Interior, the Colorado State Land Board, and private donors. The Baca Ranch included land in valleys and mountains, from 7,500 feet (2,286 meters) west of the dunes to the 14,165-foot (4,317-meter) summit of Kit Carson Peak. This purchase made the monument three times larger. The ranch was divided into three parts: the Sangre de Cristos section became part of the Rio Grande National Forest; the area west of the dunes became the Baca National Wildlife Refuge, managed by the Fish and Wildlife Service; and the area east of the dunes was first added to the Rio Grande National Forest and later became a national preserve managed by the National Park Service. Hunting is allowed in the preserve, but logging and mining are not.
In 2016, the federal government began buying 12,518 acres (19.6 square miles; 50.7 square kilometers) of the Medano–Zapata Ranch from the Nature Conservancy. This land is within the current park boundaries and includes the bison herd’s area, as well as meadows and wetlands. The goal is to complete the park, making it fully accessible to the public.
In May 2019, the Great Sand Dunes National Park and Preserve was named an International Dark Sky Park by the International Dark-Sky Association.