The Patapsco River and Valley

NOTICE: Due to the flooding event on May 27, 2018, portions of the Southern end of Patapsco Valley State Park remain closed. The closures will affect those visiting the Avalon area and Hilton area. Lost Lake remains closed including the Grist Mill trail. Please see the Alert page for the most updated information.

Avalon History Center. Founded in 1907 as the Patapsco Forest Reserve, Patapsco Valley State Park is Maryland’s oldest state park. It is the site of some of Maryland’s earliest mills and factories, America’s first common-carrier railroad, and the world’s first underwater hydroelectric plant.

Catastrophic floods have damaged or destroyed many of the valley’s historic structures and sites. As you travel through the park, whether by foot, bicycle or car, keep an eye out for historic structures, sites and ruins. Wayside interpretive signs will help you discover the valley’s rich history, especially in the Avalon and Orange Grove Areas. Be sure to bring a park map with you on your journey.

Please note that on busy summer weekends, several park areas, such as Avalon, Orange Grove and Daniels, often fill to capacity. Be sure to arrive early if you plan to come on the weekend.

Historic Sites

There are four main areas of the park where trails, historic sites, and parking lots are grouped together. Each area - Avalon, Orange Grove, Hollofield and Daniels - offers unique sites and experiences. The areas as listed below follow a geographical sequence upstream.

Elk Ridge Landing and the Elk Ridge Furnace

Elk Ridge Landing, established in 1690, was a prominent colonial deep-water port, similar to Annapolis and Joppa. Prior to the establishment of Baltimore, Elk Ridge Landing was a "gateway" for shipping agricultural products, natural resources and manufactured goods from the Patapsco's many tobacco plantations. Thanks to erosion caused by deforestation, Elk Ridge Landing silted in and was no longer a serviceable port by 1868.

Elkridge was also the site of one of Maryland’s first iron furnaces: Elk Ridge Furnace. Built by Caleb Dorsey in 1755, the furnace manufactured “pig iron”-- cast iron that was worked into implements such as nails, horseshoes and shovel spades by blacksmiths. The furnace reportedly supplied cannons and ammunition during the Revolutionary War.

You can view a portion of Elk Ridge Landing at the historic Elkridge Furnace Inn restaurant. From U.S. 1 North in Elkridge, turn right on Levering Avenue. Go one block, and turn left on Main Street. Follow Main Street one block, and turn right on Furnace Avenue. Proceed down Furnace Avenue to the Furnace Inn on your left. Furnace Inn is a part of the State Park that is leased as a private inn and conference center. The buildings that make up the Elkridge Furnace Inn restaurant complex date to the early-to-mid 1800s, and only scant ruins of the furnace itself remain along the river bank. This curatorship/lease arrangement aids the state in preserving this historic building, while providing public access to this historic structure.

Avalon Area

The Avalon Area consists of the Thomas Viaduct and the William Offutt Visitor’s Center, plus sites of the Avalon Iron Works, the Avalon Water Works, Camp Tydings, and Lost Lake.

The Thomas Viaduct was completed in 1835 and is the world's largest multiple-arched stone railroad bridge with a curve. Built by the Baltimore & Ohio Railroad, the Thomas Viaduct makes up the first leg of the railroad’s Washington Branch. It is named for the B&O’s first president, Philip Thomas. The viaduct is located just west of the Avalon Area contact station. Enter the Avalon Area of Patapsco Valley State Park off U.S. 1 at South Street, just north of Elkridge. Proceed on Park Entrance Road to the contact station. Temporary parking is available in front of the contact station. An interpretive sign is located at the contact station. To view the bridge, carefully walk down the road to examine the Viaduct, keeping in mind the danger of the blind curve on the roadway. Please note that the viaduct is still an active railroad. Do not, under any circumstances, approach the tracks or cross the bridge.

The William Offutt Visitor’s Center is one of the few surviving buildings from Avalon Iron & Nail Works. Built in the 1830s, this tiny stone duplex was home to at least two families employed by the forge, which operated nearby from 1761 to 1868. The Visitor Center is currently undergoing restoration and is not open to the public. Interpretive exhibit panels are located on the grounds near the Visitor’s Center. Also near the Visitor’s Center are the remnants of the Baltimore County Water and Electric Company’s water filtration plant. Also known as the Avalon Water Works, the water treatment plant supplied clean water to local communities in the early 1800s. The Visitor’s Center can be reached by following the Avalon entrance road to the end, making a right at the “T” and then parking in the parking lot on the right.

Old Gun Road stone arch bridge spanned the millrace that supplied water to Avalon Water Works. The age of this bridge is unknown, but is believed to date back to either the early 19th or 20th century. The Gun Road stone arch bridge is located across from the Avalon Visitor Center parking lot.

Near park Shelter #1 are the remains of Camp Tydings, a Civilian Conservation Corps (CCC) Camp that operated between 1933 and 1942. The CCC was created in 1933 as part of the New Deal, and employed young men to work on environmental conservation projects, which helped shape many of the parks we still enjoy today. Following the start of World War II, the CCC camp was converted to the nation's first conscientious objectors’ camp. Shelter #1 can be reached by following the Avalon entrance road to the end, making a right at the “T” and then the next immediate left.

Lost Lake is a man-made lake that once was part of the Avalon Dam and millrace. Please note that due to a recent flood, Lost Lake and the Grist Mill Trail remain closed until further notice. After Tropical Storm Agnes bypassed Avalon Dam in 1972 (part of it survives on the other side of the river), a new Lost Lake was built by DNR to replace the original. It is called Lost Lake because during much of the year an algae layer covers the pond. Lost Lake is located at the end of the same road at Shelter #1 (see above).

At the end of Lost Lake parking lot is the eastern terminus of the Grist Mill Trail. Along the Grist Mill Trail between Avalon and Orange Grove are the remnants of a tanker truck that was deposited on the river bank by Tropical Storm Agnes in 1972.

Orange Grove Area

The Orange Grove Area consists of Swinging Bridge, ruins of the Orange Grove flour mill, and the sites of Bloede’s Dam and the Patterson Viaduct.

The Swinging Bridge spans the Patapsco River at Orange Grove, 1.6 miles northwest of Avalon, following Park Road beyond shelters 104 and 105. Previous suspension foot bridges at this location enabled residents of the Orange Grove mill town to cross the river to Baltimore County. This was especially helpful for those who worked at the C.A. Gambrill Manufacturing Company’s Orange Grove Flour Mill, which stood five stories high. Orange Grove flour was sold in white bags whose tops were string tied and whose labels proclaimed "Patapsco Superlative Flour." This mill burned down on May 1, 1905. Cross the bridge to discover ruins of this large mill site that extended from the railroad tracks to the Swinging Bridge abutment.

The site of Bloede Dam is located about a mile upstream from Orange Grove. It is believed to have been the world's first submerged electric-generating plant. Local businessman and philanthropist Victor G. Bloede and electrical engineer Otto Wonder developed this unique and experimental hydroelectric dam, which operated from 1907 until about 1930. The dam was removed in 2018 to restore passage for migratory fish. To see the dam site, follow the River Road (on foot or by bicycle) upriver beyond the Orange Grove Shelter, or follow the Grist Mill Trail (across the river) upstream.

The Patterson Viaduct was built for the Baltimore and Ohio Railroad in 1829. Named for B&O director William Patterson, the bridge spanned 375 feet with four arches. The bridge’s lifespan was relatively short; a flood swept away three of its arches in 1866. An iron bridge was built in its place until the line was bypassed in 1903. Today, the remaining abutment and arch support the “cable-stay” bridge that makes up the western terminus of the Grist Mill Trail.

Hollofield Area

The Hollofield Area consists of the Union Dam, the Union Dam Tunnel and the U.S. 40 Bridge.

The first Union Dam was built in 1810 by the Union Manufacturing Company for a cotton mill, which was located in present-day Oella, over one mile downstream. The mile-long millrace was intended to power several mills, but only powered one. The original stone and wood dam was replaced by a concrete dam in the early 1900s. Tropical Storm Agnes diverted the river around the dam in 1972. When the concrete dam was removed in 2010, remnants of the original dam were revealed. Today, you can visit the dam site by following the Union Dam Trail beyond Hollofield Shelter 300 down into the valley.

The nearby Union Dam Tunnel was built by the Baltimore & Ohio Railroad in 1902 to bypass a tight, narrow curve around around the hillside. The tunnel is on private property and is still an active railroad. Please view the tunnel from a safe distance and do not approach the tracks.

The U.S. 40 Bridge, originally called the Edmondson Avenue Extension Bridge, was built by the State Roads Commission in 1936 to carry Baltimore National Pike across the Patapsco Valley. Built of reinforced concrete, the bridge features 27 small arches overtop of a 180 foot-long gentle arch. Hollofield is named from the last owners of Ellicott’s Upper Mills, which was established in the late 18th century. A clerical error has caused the misspelling of “Hollifield” to stick and the park area today is called “Hollofield.”

Daniels Area

The Daniels Area consists of the Daniels Dam, the ruins of the towns of Daniels and Guilford and the original road bed of the Baltimore & Ohio Railroad.

The Daniels dam once powered the mill and town of Daniels. Originally called Elysville, then Alberton, Daniels was founded in the 1840s as a textile mill. In the 1860s, the mill produced canvas tents for the Union Army. The current name, Daniels, came from the C.R. Daniels Company who took ownership of the mill in 1940. The mill company demolished much of the milltown in 1968 and Tropical Storm Agnes destroyed the mill in 1972. To visit the Daniels dam and town site in Baltimore County, take Route 29 North to its termination at Route 99, Old Frederick Road. Turn right on Old Frederick Road and proceed to the first left, which is still Old Frederick Road. Proceed about one half mile to a left on Daniels Road where you drive about one mile to a parking lot on the left and the dam will be on your left. Please note that the site of the original mill, along with the surviving James A. Gary Methodist Church, are on private property. Do not trespass.

To see the ruins of Guilford, the milltown on the Baltimore County side of the river, hike on Old Alberton Road. Guilford was built as part of the Alberton/Daniels mill town, but because it was built on the other side of the river, it had its own identity. To reach old Alberton Road, take Daniels Road back to a left on Old Frederick Road. Follow Old Frederick Road to the railroad crossing and steel bridge at the "T" intersection across the bridge where you turn left on Hollofield Road. Proceed .3 miles to a "T" intersection with Dogwood Road. Turn left over a bridge, then turn left immediately into Alberton Road. Park in the lot before the cattle gate. Proceed through the gate passed the private home on the hill. Hike the Alberton road behind the gate and along the river. Please use caution when exploring the ruins.

Much of the Old Main Line Trail west of Daniels on the Howard County site follows the original alignment of the B&O Railroad as it was laid out in 1831. It was found to be too windy, even in the 1830s, and part of this line was bypassed by a short realignment in 1838, and then completely bypassed in 1907. Bridge abutments and piers from the 1838 realignment are visible near Daniels Dam and about a half-mile upstream.

For Further Reading…

Cramm, Joetta M., A Pictorial History of Howard County, Donning Publishing, 1988.

Dilts, James W., The Great Road: The Building of the Baltimore and Ohio, the Nation’s First Railroad, 1828-1853, Stanford University Press, 1996.

Harwood, Herber H., Impossible Challenge II: Baltimore to Washington and Harpers Ferry, 1828-1994, Barnard Roberts, Inc., 1994.

Sharp, Henry K., The Patapsco Valley, Cradle of the Industrial Revolution in Maryland, The Maryland Historical Society, 2000.

Travers, Paul J., The Patapsco: Baltimore’s River of History, Shiffer Publishing, 2016.