A 1990 study by the U.S. Fish and Wildlife Service revealed a startling fact: more than half of the 221 million acres of wetlands that existed in the lower 48 states in the late 1700s have been destroyed. Since the 1990s, the NPS has operated under a “no-net-loss of wetlands” policy. Under this policy, any construction or other activity on park lands that has adverse impacts on wetlands must compensate by restoring at least 1 acre of wetlands for each acre degraded or destroyed. This and other NPS wetland protection policies have kept new impacts on wetlands to a minimum.
However, thousands of acres of wetlands in our national parks have been damaged or destroyed by land-use practices and activities that occurred before they became part of the national park system. NPS management policies address this concern with a “net gain of wetlands” goal, to be accomplished through restoration. Specifically, our wetland policies direct parks to identify sites where wetlands have been degraded or lost due to human activities and restore them to their pre-disturbance conditions.
Cape Cod National Seashore, Everglades National Park, Assateague Island National Seashore, Indiana Dunes National Lakeshore, Denali National Park, Redwood National Park and many other NPS units are restoring wetlands of all types. Here are some of the wetland restoration projects NPS Water Resources Division (WRD) staff have helped design and implement across the Service.
From the 1950s through the early 1990s, thousands of cubic yards of gravel were extracted from the Snake River floodplain in John D. Rockefeller, Jr. Memorial Parkway, primarily for road projects on federal lands. Closure of this gravel pit in 1992 left over 60 acres of poorly vegetated waste piles and steep-walled borrow ponds that were visible from the road connecting Grand Teton and Yellowstone National Parks. During the late 1990s, the NPS obtained funding to design and implement a restoration plan for the abandoned mine site.
WRD staff, Colorado State University cooperators and park staff collaborated on the restoration design. They based the design on extensive analysis of soil, vegetation, and hydrologic data collected within the mined area and in nearby, undisturbed floodplain and wetland systems. These undisturbed “reference areas” served as models for creating the desired habitat types in the mined area. Special factors that had to be addressed included the complex hydrology of the site, the need to protect existing western boreal toad breeding habitat, and beneficial use of topsoil that had been set aside during the mining process.
Under the direction of the design team, contractors used heavy equipment to reshape more than 268,000 cubic yards of mine waste to create the contours specified in the grading plan. Crews then installed thousands of willow cuttings and hundreds of thousands of wetland plants to create 50 acres of sedge meadows, willow flats, stream channels, oxbow ponds, and upland features. Grizzly bears, moose, bison, trumpeter swans, sandhill cranes, western boreal toads and many other wildlife species now inhabit the restored site.
Each year, thousands of visitors pass through Halstead Meadow as they drive the Generals Highway toward the park’s famous giant sequoia groves. In its natural state, this wet meadow and fen system provided important habitat for plants and animals and offered scenic beauty and wildlife viewing opportunities for visitors. However, intensive livestock grazing in the early 1900s stripped away wetland vegetation and the meadow developed deep gullies that drained the site. Damage intensified in 1934 when the highway was built across the meadow and water was directed through a pair of culverts under the fill. By 2005, the main gully was 2000 feet long, up to 15 feet deep, and up to 85 feet wide. It lowered the water table, dried and washed away soils, altered vegetation communities and curtailed wetland functions on about half of the 21-acre meadow.
In 2007, NPS staff and cooperators from Colorado State University began a pilot restoration project in Upper Halstead Meadow. Contractors placed 8,100 cubic yards of fill in the gullies to recreate the original meadow contours and installed erosion control fabric and fallen trees to help stabilize the site. The next spring, crews installed more than 53,000 native wetland plants to establish the dense vegetation needed to spread sheetflow across the site and stabilize soils.
The team incorporated “lessons learned” from the pilot project into the design for the Lower Halstead Meadow restoration. A critical step in this second project phase was having the Federal Highway Administration replace the old highway fill and culverts with a new bridge spanning the entire meadow. Once the bridge was finished in 2012, contractors back-filled the gullies in the lower meadow to restore the original topography and placed alternating strips of erosion control fabric and native sod on the bare soil. The team then released water from the upper meadow under the bridge and onto the lower meadow as sheetflow, which reconnected the two restored areas and reestablished the natural hydrology of Halstead Meadow. The following spring, crews installed thousands of native wetland plants to complete the lower meadow restoration. By 2015, the entire 21-acre wet meadow was once again stable and functioning as it did before the damage occurred.
Prisoners Harbor, a primary Santa Cruz Island visitor destination near the mouth of Cañada del Puerto Creek, is rich in cultural and natural history. The Chumash people called the island home for 10,000 years, until the late 1820s. In the 1830s, an unsuccessful penal colony was established on the island, giving the harbor its name. In the late 1800s, ranchers settled the island and developed the lower Cañada del Puerto area as a livestock holding facility. In doing so, they filled the largest coastal wetland system in the Channel Islands. This eliminated vital habitat for migratory waterfowl and for wildlife found only on the Channel Islands, including Santa Cruz Island foxes and Island scrub-jays. They also rerouted the creek and built a flood protection levee along its lower banks, which disconnected the creek from its floodplain and exposed a 5000-year old Chumash Village archeological site to erosion.
In 2004, park managers asked for assistance from WRD in developing wetland and stream restoration concepts for Prisoners Harbor. Goals included reestablishing habitat for migratory waterfowl and resident wildlife, protecting the archeological site, and improving the visitor experience. WRD and park staff based the restoration design on detailed investigations of hydrology, vegetation, soil, and topography at the former wetland site and in nearby “reference wetlands” that served as models for restoration. The grading plan called for excavating 10,000 cubic yards of fill to restore the coastal wetlands and reconnect the stream to its floodplain. Careful consideration was given to both wetland function and visitor enjoyment. For example, willow stands were oriented to provide screening and cover for waterfowl, and overlooks were established to provide visitors with opportunities to observe wildlife and learn about restoration.
During October-November 2011, contractors completed earthmoving and erosion control work according to design specifications. In the following months, park and WRD staff, volunteers, and Los Angeles Conservation Corps (LACC) crew members installed over 15,000 native wetland plants to complete the restoration. LACC’s primary mission is to provide at-risk young adults with opportunities for success by providing them with job skills training, education and work experience, with an emphasis on conservation and service projects. In addition to benefitting from the LACC crew’s hard work on the project, the NPS staff enjoyed and learned from many interesting discussions with them.
In addition to preserving 10,000 years of human history, Pecos National Historical Park in New Mexico is responsible for managing riparian and wetland habitats along Glorieta Creek and the Pecos Wild and Scenic River. One such area, a half-mile stretch of floodplain and terraces along lower Glorieta Creek, was mined for sand and gravel before becoming part of the park. Once mining ended in the mid-1980s, ranchers bulldozed the remaining material into levees and created two reservoirs on 5.6 acres. The reservoirs soon became a threat to the ecology of Glorieta Creek. Floodwaters periodically swept thousands of fish from the creek into the reservoirs, where they were trapped and later died as the ponds dried. Flooding also caused breaches in the progressively weakening levees, washing sediment into the creek and toward the Pecos River approximately ½ mile downstream.
During 1998-2000, park managers received technical assistance and funding to create a more stable, functional riparian-wetland ecosystem in this highly disturbed landscape. WRD staff and Colorado State University cooperators completed restoration grading and planting plans and developed contract specifications. Earthmoving contractors excavated 30,000 cubic yards of material from the levees and reservoir bottoms to achieve the contours specified in the restoration design. In the spring of 2000, crews planted over 1000 willows and cottonwoods and nearly 10,000 native sedges, rushes, bulrushes, and spike rushes across the site. One section of levee was left in place to provide short-term flood protection for the newly planted area until soil-stabilizing plant cover could take hold.
In 2007, the design team revisited the site to evaluate project success and make further management recommendations. They found that cottonwoods and willows were thriving and native wetland plants had formed nearly 100% cover. A contractor removed the remaining levee segment in 2013, and the site is now performing natural and beneficial functions including maintenance of natural stream channel, floodplain and wetland habitats, water quality improvement, sediment retention and flood storage.
Palo Alto Battlefield NHP is located near the mouth of the Rio Grande River, just north of Brownsville, Texas. In 1846, this site was an open wet prairie straddling the historic road between the fishing village of la Punta de Isabela and the town of Matamoros, Mexico. The Mexican army selected this strategic position to intercept United States forces that were moving to relieve the besieged Fort Brown, located 10 miles away on the banks of the Rio Grande. This was the first major battle of the war between Mexico and the United States over disputed territory north of the Rio Grande. The prairie landscape at the park includes several abandoned stream channels known locally as “resacas.” The resacas fill with water after rainstorms and remain ponded for weeks or months, creating wetland conditions. One of these channels, the Palo Alto Resaca, played a strategic role in placement of the Mexican and U.S. battle lines and affected troop movements during the battle.
Although the prairie and resacas retain some of their original characteristics, agriculture, ranching and drainage projects occurring long after the battle altered the historic landscape. The dominant plant species of the prairie, gulf cordgrass, was removed and the ground was plowed for agriculture. Cordgrass has not recolonized the core battlefield, even decades after agriculture ceased. Landowners also dug over 8000 feet of ditches along the resaca margins to drain water into stock ponds, and they deposited the excavated soil as levees along the resaca banks. Visitors walking the interpretive trails leading to the Mexican and American battle lines or viewing the battlefield from the raised overlook must now see past these distractions to connect with the historic events that took place there. A major goal of the park is to remove these man-made features and restore the landscape so that visitors can fully understand and experience the conditions that shaped the battle. This restoration also meets the NPS’s goal to preserve the valuable natural resource functions that these wetlands once provided, but that are much reduced due to disturbance.
A project is now underway to restore the core battlefield area of the park. In February 2017, the drainage ditches, stock ponds and artificial levees were completely removed, restoring the land contours that existed at the time of the battle. Working with Natural Resources Conservation Service, WRD and university cooperators, the park established a small plant nursery facility at the battlefield. Thousands of gulf cordgrass seedlings have already been planted on the site, and up to 100,000 more seedlings will be installed in 2018.
Moores Creek National Battlefield in eastern North Carolina commemorates a Revolutionary War battle that occurred in and adjacent to a pine savanna wetland there. More than 100 years after the battle, landowners installed a drainage ditch and tile system and converted the site mostly to dry meadow and woodland. Despite the drying, relic populations of insect-eating pitcher plants and state threatened wetland species like Carolina bog mint and spring flowering goldenrod have persisted in small, undrained pockets at the site. Once the park was established, the NPS built a visitor center just above the meadow and developed interpretive trails to lead visitors through the battlefield.
By the late 1990s, a park objective was to reestablish the landscape that existed at the time of the Battle of Moores Creek (1776), while preserving the rare native plant species that were still found in small numbers there. Park staff worked with WRD, The Nature Conservancy, the North Carolina Heritage Program, the U.S. Environmental Protection Agency, and others to restore the former wet pine savanna habitat. The project team installed shallow wells at the site to document existing (pre-restoration) hydrologic conditions. They also prepared an evaluation of existing vegetation that included a plant community map, locations of rare species, and identification of relic wet pine savanna species. The team recommended a 3-5 year prescribed burn cycle that would help control weedy species and promote recovery of native pine savanna vegetation once the hydrology was restored.
In late 1998, the project team conducted a hydrologic restoration experiment. Park staff blocked and backfilled the ditch at a location that would simulate its full removal, and they monitored the existing well network for more than a year. Monitoring results showed that plugging the ditch restored hydrologic conditions that could once again support a wet pine savanna ecosystem on most of the site. The park decided to keep the ditch plugged permanently, and obtained funds to grow and install 25,000 wet pine savanna plants in 2005-2006. The recommended 3-5 year prescribed burn cycle is now being put into effect, and the park continues to plant longleaf pines, the signature tree species of wet pine savannas.