Exploring the Hidden History Beneath Maryland’s Patuxent Reservoirs

Añadido: 2026-05-12

[00:00:00]You're driving south on Interstate 95 in Maryland between Baltimore and DC. As you leave Howard County, have you ever glanced to your right to see this oddlooking structure? It's obviously a dam, but what's it doing here? Right next to the highway, and what hidden history lies just beyond? Let's find out. Hey, Zach here. Today, I'm at Rocky Gorge Reservoir in Maryland. And if you're wondering what's behind the dam in my thumbnail picture, this lake is just part of the answer. Rocky Gorge is one of two lakes that were built along the Puxen River in the mid 20th century to supply water to neighboring counties.

[00:00:38]But beneath these waters lie the remnants of old roads, bridges, and even entire towns that once stood along the Puxen River. In this video, we're going to explore some of that hidden history and try to discover some of the traces that still remain today.

[00:00:54]Rocky Gorge Reservoir sits almost dead center between Baltimore and Washington DC and it forms the border between Howard County in the north and Montgomery and Prince George counties to the south. The lake extends for nearly 10 miles behind the dam, which had its official name changed to T. Howard Ducket Dam in 1967.

[00:01:17]Duckett was one of the founders of the utility company that constructed the dam, the Washington Suburban Sanitary Commission or WSSC.

[00:01:26]Because of this name change for the dam, the lake is often referred to as the T.

[00:01:31]Howard Ducket watershed, but I will probably stick with calling it Rocky Gorge since it's shorter.

[00:01:38]The dam itself is off limits to the public, so our best vantage point is from the air. And if you're wondering why it was built so close to the highway, you actually have it backwards.

[00:01:50]The dam was built nearly 20 years before I 95 was completed through the area.

[00:01:56]This 1971 view shows the highway being built next to the already decades old dam. And this view from the dam shows the nearly completed highway almost ready to open for traffic. Note the pumping station just down from the dam, which is used to send water to filtration plants down river. This station, which still exists, actually predates the dam, and its location partially determined where the dam would be built.

[00:02:28]The Rocky Gorge Dam was built between 1952 and 1954 when the WSSC acquired over 3,000 acres that would become the reservoir. This image looks upriver with the dam construction at the bottom and the dotted line denoting the planned location of the lake. You can get an idea from this photo why the initial name of the dam and lake was Rocky Gorge. Another view closer to the ground, but looking in the same direction better shows the contours along the old riverbed features which are now completely submerged beneath the lake.

[00:03:05]Backing up just a little bit, we can see the dam structure being built. Note the cable system at the top of the image, which was used to place forms and deliver concrete to the construction site. This image from March of 1954 shows the nearly completed dam with the cableways still in place overhead. Note the already rising water levels behind the dam. The completed dam is 131 ft high and 840 ft across and it holds back on average 5 1/2 billion gallons of water at an average depth of 75 ft. From our elevated vantage point, we can zoom in to see some of the finer structure, including the steep spillway and the seven floodgates, which are all currently closed. The lake is fairly low at the moment, so there's no need to have them open. The gates themselves aren't really a means of preventing floods as much as safeguarding the dam.

[00:04:08]In 1972, during Tropical Storm Agnes, all of the floodgates were opened to alleviate pressure behind the dam. A similar situation occurred in early 2013.

[00:04:21]In both cases, the excess water quickly made its way downstream to Laurel, leading to instances of flooding in the low-lying areas of the city. As bad as this was, it's surely preferable to the catastrophic flood that would result from the dam actually failing. To alleviate concerns of the dam failing, improvements were made in the early 201s to fortify the dam to withstand a 1 in 10,000year flood. Their words, not mine.

[00:04:52]Hopefully, these improvements are never put to the test. The lake behind the dam serves as a source of drinking water for Montgomery and Prince George counties, but it also provides numerous recreational opportunities for visitors who purchase a permit from WSSC.

[00:05:09]I visited the Sup Lane Recreation Area on the south side of the lake. And this location offers a boat launch for non- gasoline powered craft, playgrounds for kids, walking paths, and miles of shoreline for fishing.

[00:05:41]The place is pretty empty today, but there is one boat out on the water. It must be a water company employee, though, since it appears to be a powered boat.

[00:05:52]These days, the watershed and its immediate surroundings are an idyllic recreation spot isolated by the water company's buffer property around the lake. And this becomes even more obvious as we transition to modern aerial imagery, where the lake is completely surrounded by forests. The only major highway crossing the lake is Maryland Route 29. But what was here before the reservoir? To explore that, we're going to travel back in time gradually to catalog the changes as we go. Note the bottom left as we transition to our first stop, 1977.

[00:06:30]The only major change is Route 29 shifting back to a previous alignment.

[00:06:35]Other than that, the area around the lake looks largely unchanged and all of the local highways are present and accounted for. Traveling back to 1963, we do lose I95 and Maryland 216, but the lake property is still unchanged.

[00:06:53]Going back further to 1952, now things are getting interesting. Now, all of the local highways are gone except for a small sliver of 29 that looks to be under construction at the top of the screen. This far back in time, the lake itself is gone, too. Although construction has obviously started in the area where the dam will be upstream, the river valley looks largely untouched from the construction and moreover, it looks devoid of any real development at all. There are certainly no towns and even individual homes are few and far between.

[00:07:31]Our final stop is 1943, long before any construction was started on the lake.

[00:07:36]Here we see the river valley in its undisturbed state. And if we overlay the watershed property onto the image, we can see that there were a few farms on the Howard County side that were displaced by the lakes's construction.

[00:07:50]But overall, the land still looks largely undeveloped. Now, this aerial image is a little too cluttered to discern any fine details. So, let's look at a topographical map from around the same time.

[00:08:04]Here, the structures are denoted by black squares, so it's a little easier to see the properties affected by the lakes's construction.

[00:08:13]Aside from the affected properties, there is one major road that crossed the Puxen River in this area, the old Colombia Turnpike. This road actually dates back to the early 1800s, and it used to connect the District of Columbia to Elicate Mills, the present-day Elicate City. This old road is interesting enough to have a whole video devoted to it, and I hope to do one in the future, but for now, let's just focus on this small section that crossed the Puxen River. If we transition back to the modern aerial view, we can see that while some sections of the original road survive on the north and south sides of the lake, the original river crossing now sits at the bottom of the lake. A more modern bridge, built shortly after the lake was constructed in the 1950s carries the present-day Route 29 over the reservoir. But is there anything left of the old alignment? Let's go check it out.

[00:09:10]Starting where the old Columbia Road ends on the north side of the lake.

[00:09:15]Here we are looking north on Old Colia Road. And as we turn toward the lake, we can see that the road ends at a trail head.

[00:09:35]And towering above the park information board is a road sign telling us that we're on the right track.

[00:09:57]This trail follows the path of the old road. And while it is mostly gravel covered, there are some small hints of the old paved surface.

[00:10:16]It's hard to tell on the camera, but we have been descending over the whole length of this trail, and we can see where it drops down to water level ahead.

[00:10:42]I had hoped to see a paved section of the road disappearing into the lake, but it seems like all hints of the road here have been washed away.

[00:10:53]We can see the modern Route 29 bridge in the distance, carrying the successor to this old alignment. But what about the old river crossing here?

[00:11:04]Until the lakes's creation in the early 1950s, arriving at this spot would have afforded us this view with the old road crossing this steel truss bridge. This bridge was built in 1883, replacing a series of wooden bridges that sat at this same location, dating back to the road's initial construction in the early 1800s.

[00:11:28]This bridge was double span, and it had a single pillar in the middle, and the road surface was wooden planks.

[00:11:36]Looking up river, we get a better view of the pillar, as well as an old car sitting on the bridge. The steel from the bridge was likely salvaged when the lake was built. But if anything survives of the pillar or the abutments, they've been submerged beneath these waters for over 70 years.

[00:11:55]But what about old Columbia Road on the other side of the lake? Well, on the south side, I actually get my wish and find the paving disappearing into the lake.

[00:12:10]And as we turn to the south and head up the hill, we can see the old road is much more intact on this side, although I still wouldn't want to drive on it.

[00:12:27]There also seems to be much more of a climb on this side to get out of the valley.

[00:12:33]I wonder how the cars in the early 20th century fared on this stretch of road.

[00:13:16]We can see the cars zooming by on busy Route 29 just beyond the trees.

[00:13:32]And here is where the old road meets up with the current highway.

[00:13:37]Old Columbia Pike would have crossed the modern road at a diagonal here on its way to Burtonville as shown by our starred position on this map. And so it turns out that aside from a handful of farms and a section of old road, not much of significance was lost to the construction of Rocky Gorge Reservoir.

[00:13:58]But can that also be said for the other lake on the Puxen River, Triadadelphia Reservoir, which sits 13 miles upstream from Rocky Gorge? Just like the reservoir downstream, Triadadelphia forms the border between Howard and Montgomery counties. But one of the major differences here is how accessible the dam is compared to the one at Rocky Gorge.

[00:14:23]From the visitor center, you just have to walk down the hill and the dam is right there.

[00:14:41]There are even some recreational areas just below the dam.

[00:14:53]Brighton Dam is actually older than Rocky Gorge, having been completed in 1944.

[00:14:59]It was built by the same construction firm as Rocky Gorge, leading to its very similar construction style, albeit this dam is significantly wider and shorter than the one downstream, coming in at 82 feet high and 1,000 ft long. With that longer length, Brighton has 13 floodgates compared to the seven at Rocky Gorge. Interestingly, since this dam was built at the height of World War II, German PSWs housed in Frederick were used as manual labor during its construction.

[00:15:33]I'm sure this area below the dam is a popular fishing spot. And not just for humans.

[00:15:44]This fella looks like he's having about as much luck as I usually do while fishing.

[00:15:50]Another major difference compared to Rocky Gorge is that Brighton has a busy road crossing over top.

[00:16:04]From the north side, we can get nice views of the lake, which looks just about as low as Rocky Gorge was.

[00:16:14]And from the other side, a bird's eye view of the spilling basin.

[00:16:20]Now, one of the main draws to this location in the springtime is the Brighton Aelia Garden, which sits just west of the dam and across the road from the visitor center.

[00:16:32]The Aelia Garden at Brighton Dam was established in 1959 and is home to over 22,000 Aelia bushes spread over 5 acres.

[00:16:43]In addition to the aelas, dogwood trees were added in the 1990s.

[00:16:50]I just happened to come here around peak bloom time. And while I was blissfully unaware of that fact, it seems like everyone else definitely knew. I could barely find a parking space in the visitor lot.

[00:17:39]Incidentally, the Aelia Garden does offer decent views of the upper side of the dam.

[00:17:46]Just like Rocky Gorge, Triadadelphia is primarily a source of drinking water, but it does offer a number of recreation areas catering to boating, fishing, hiking, and other activities. Usage permits are required, and they can be purchased online or at the visitor center at Brighton Dam.

[00:18:06]Now, similar to what we did at Rocky Gorge, let's explore what was here before the lake was built. But because Triadadelphia is such a big lake, we're going to split it up into two historically significant sections. One in the south near the dam and the other towards the northern extremity of the lake. First, let's look at the southern region. I've labeled a couple roads of importance, including Greenbridge Road, which dead ends at the Greenbridge Recreation Area. I'm going to cycle back fairly quickly because not much changes here over the years.

[00:18:45]1943 is as far back as we can go with these highresolution aerial images and unfortunately the construction of the lake has already begun by this point. So there is no opportunity to see what the landscape looked like before.

[00:19:00]Nevertheless, we can see a hint of something interesting just below center frame where it looks like Greenbridge Road once crossed where the lake now sits. To verify this idea, let's go further back in time to the 1923 topographical map where we can see that Greenbridge Road did indeed cross the lake. Moreover, it intersected with another road heading to the northeast.

[00:19:26]And at that intersection, which would now be underwater, the black squares on the map imply that some buildings once stood. It's worth noting that Brighton Dam Road, which I still have marked on the map, hasn't been built yet in 1923.

[00:19:41]Greenbridge Road is the main East West thoroughfare and likely remained so until the lake was built and Brighton Dam Road replaced it. We're going to go back in time once more to the 1860 Martinet map to get one more piece of the puzzle. Here we see that the area of this intersection was actually called Green's Bridge. I dug a little further and found some information from the minutes of local court proceedings.

[00:20:10]During the March 174748 court term, Richard Snowden applied for a contract to rebuild three bridges over the Puxen River near Hyets, between William Richardson and John Gaither, and near Richard Green's Mill. This is almost certainly referring to the Greens Bridge shown here, implying that this road was an important east-west route dating back to colonial times.

[00:20:38]Let's highlight the East West Road as well as the one branching to the northeast before transitioning back to the present.

[00:20:46]This shows us that the entire intersection now sits at the bottom of the lake, including the locations of the old bridge and likely Green's Mill, too.

[00:20:57]Moreover, we can see the point where Brighton Dam Road diverges from the original alignment east of the lake. The surviving stub of a road on that side serves as a driveway to multiple residences.

[00:21:10]The road heading northeast from Green's Bridge has been completely obliterated from the map. Now, I want to travel in time once more. This time to early 2018 when the lake was at an historic low point. I'm going to zoom in, and I want you to focus on these two spots as I remove the red highlight. We can see on the left the point where Green Bridge Road disappears into the lake. But even more interesting is the trace of road that we can see on the right. And right next to it seems to be the foundation of a structure that once sat next to the road. These days, the lake is nowhere near low enough to see the remnants on the right, but we can visit the Greenbridge recreation area to see what we can find there.

[00:21:57]This boat ramp utilizes the end of the Greenbridge Road on this side of the lake.

[00:22:04]I'm guessing the paving on this ramp is a fairly recent improvement to the boat launch. There is no way the old road would look this good after 80 years underwater.

[00:22:17]We can see the dam in the distance.

[00:22:32]Unfortunately, despite my best efforts, I wasn't able to find any pictures of Green's Bridge. And while the lake is certainly a beautiful site, it's time to move on to our northern section of interest.

[00:22:45]It was here, roughly at center frame, where sat the old village of Triadadelphia, the lakes's namesake.

[00:22:53]Unfortunately, even if we jump all the way back to the 1943 aerial, we are still too late to see the village as the lakes's construction has already wiped it out. The 1923 topographical map is a little more informative, showing the road that crossed the river as well as the main street of the town lined by structures. But even by that point, the town was over a 100red years old.

[00:23:20]Triadadelphia was founded in 1809 when three enterprising men from nearby Brookville set up a cotton mill along the Puxen River. Around the mill, a small town quickly grew that eventually included a store, a church, a school, and a number of houses to accommodate the mill workers. Unfortunately, the mill at Triadadelphia was never very successful as it had a number of factors working against it. First and foremost was its location away from easy transportation routes which made receiving raw materials and shipping finished products very costly.

[00:24:01]Additionally, the Triadia Mill couldn't compete with the larger, better positioned mills in the state, which offered lower prices and a wider variety of products. The company changed hands a number of times throughout the 19th century and even had to deal with disasters in the form of fires and floods.

[00:24:22]The flood of 1889 caused such damage that it ended the mill operations in the town. However, local residents continued living in the town until they were eventually evicted in the early 1940s to make way for Triadadelphia Reservoir.

[00:24:39]These days, very little remains of the old town, but we can go check out the location on foot. Starting at the Triadia Recreation Area, here is where Triadadelphia Lake Road ends at the area parking lot.

[00:25:02]This recreation area is definitely feeling the effects of the low lake conditions.

[00:25:07]I think there should actually be water here under this pier.

[00:25:27]The boat ramp is closed for good reason.

[00:25:33]I was intrigued enough to climb this winding set of stairs. thinking there might be something interesting at the top, but nope, just a trail.

[00:25:43]I did follow it for a while, but there was really nothing of interest.

[00:25:52]This boat launch likely follows the path of the old road, but I think the paving must be fairly recent, just like at Greenbridge.

[00:26:01]There won't be any boats launching here for a while.

[00:26:13]To get to the recreation area, we follow this path around where the water should be.

[00:26:33]Check out this weird rock sticking out of the stone wall here.

[00:26:43]You can see where this path brought us with respect to the boat ramp that we were just on.

[00:26:56]This small hill hosts a playground and some limited picnic facilities.

[00:27:09]According to the old maps, the town church would have sat up here on the hill directly in front of us.

[00:27:16]I couldn't find any old pictures of it, though.

[00:27:23]This path continues down toward the lake where another small boat launch sits also well above the current water line.

[00:27:32]The old village buildings would have been in this general area here.

[00:27:38]However, I'm not really seeing any foundational remnants despite the low level of the lake.

[00:27:49]I did check the 2018 aerial imagery when the lake was historically low and I was able to spot some foundational remnants.

[00:27:58]Oddly though, they appear to be in the old riverbed.

[00:28:03]If you want to read a much more thorough examination of the various town ruins uncovered during this time, Dr. Steven Curtis has an excellent writeup called Triadadelphia exposed. I will include a link in the video description.

[00:28:19]Aside from the submerged relics, there are a couple of other leftovers from Triadadelphia that survive to the present day. Somewhere on the hill above where the village sat, the old Triadia cemetery still survives. I believe it is supposed to be around here somewhere. I did search for it, but I couldn't find it. Here is an image of the cemetery that I was able to find online.

[00:28:45]The other Triadadelphia survivor is the bell that once stood a top the old mill building. Since 1902, the bell has resided at the nearby Sherwood High School in Ashton Sandy Spring. For 50 years, the bell was used to call students, but since 1954, it has been housed in this stone structure just outside of the school building.

[00:29:16]It serves as a lasting reminder to all that was lost beneath the lakes.

[00:29:24]Well, I hope you like this look at the lakes along the Puxen River. They may seem like they've been here forever, but they're actually fairly new additions to a landscape that's been changing for centuries with a rich history hidden just below the surface. As always, thanks for watching. Please consider subscribing so that you don't miss any future content, and check out my Patreon for bonus pictures and videos. Until next time, see you later.