The Balancing Reservoir at Loch Raven

The Loch Raven Reservoir watershed property is a fascinating place full of relics of another time. An especially interesting place is the Balancing Reservoir, a decommissioned reservoir located near Cromwell Valley Park.

Take a look at the history and function of the remnants found at the Balancing Reservoir, and look at how I surveyed and added information about the reservoir to the map on

balancing shaft
The old shaft that conveyed water from a 12′ wide conduit built in 1881 to the reservoir above


Loch Raven Reservoir is a 23-billion gallon reservoir located near Towson, Maryland. The original reservoir was smaller and utilized a low dam which is still standing, downstream of the upper dam. The original lower dam connected with the Lake Montebello reservoir via a 12-foot diameter conduit. The conduit was built by tunneling underground and follows a nearly straight line to the Montebello gatehouse.

The construction of the upper dam at Loch Raven raised the water level of the reservoir from 170 feet above sea level (at the lower dam) to 188 feet and eventually to 240 feet. Raising the dam increased the water storage capacity significantly but also increased the water pressure in the 1881 conduit. The pressure presented a problem for city engineers. To reduce the water pressure in the conduit, city engineers elected to build a balancing reservoir over the conduit.

The Balancing Reservoir

How the balancing reservoir looked while in use. Via Ronald Parks.

The balancing reservoir allowed the excess water pressure in the conduit to be relieved. The facility consisted of a smaller reservoir (nine million gallons), which stored the over-pressure water in an abandoned quarry behind an earthen dam. Water would flow back into the conduit when the upstream supply decreased.

The balancing reservoir has been dry since 1946, but the earthworks remain. With a little imagination, a visitor can visualize how the reservoir worked. Thre are four main components that remain to help.

  1. The standpipe (or shaft), which conveyed water between the conduit and the reservoir.
  2. The dam, which impounded up to nine million gallons in the reservoir.
  3. The spillway, which conveyed excess water out of the reservoir, down an outfall and into Minebank Run
  4. The quarry, which provided the basis for the reservoir.

Finding the Remnants Today

The balancing reservoir became obsolete when a new tunnel opened between Loch Raven and Montebello in 1946. Though it fell out of use, all four components remain on the watershed property.

The Shaft

The shaft is technically known as a standpipe. It forms a connection between the tunnel below and the balancing reservoir above. The shaft extends from the top of the cap to the bottom of the tunnel, 55 feet in total. The exposed portion of the shaft extends 22 feet from the ground to the cap. While in operation, water from the conduit would rise through the standpipe and out one of the six 36-inch portals at the base.

A close-up look at the 36″ portals that cover the shaft.

The earthwork around the shaft is finished in concrete and sloped so that water can drain from the balancing reservoir back into the conduit. The outflow down the shaft would occur whenever the sluice gates at the Upper Loch Raven Dam were closed or were not feeding enough water to fill the conduit.

Today, the 22-foot tall shaft and surrounding concrete earthworks protrude prominently out of the earth in a wooded area just east of Cromwell Valley Park.

The Dam

A view looking along the footpath that crosses the earthen dam.

The earthen dam, clad in concrete on the inside face, is intact. The dam is 8 feet wide along the top and has a crest elevation of approximately 205 feet. The dirt used to construct the dam was excavated from the nearby hillsides.

Today, there is a dirt path that runs along the top of the dam, with a side path going down the face into the reservoir which leads to the shaft and continues to an unnamed dirt trail that connects the two parts of the Cromwell Valley Park.

The Spillway

The spillway is a twenty-foot wide concrete channel that drained excess water from the balancing reservoir, which had a low elevation of 190 feet. The spillway elevation is 200 feet at its peak, so water more than ten feet from the bottom would flow out of the spillway and into a channel that led to Minebank Run.

Today, the concrete paved channel is still intact and is a strange sight to see out in the woods. The channel is dry now, with a few trees growing through cracks. The outfall has a few danger signs to warn the public of the steep drop off beyond.

The Quarry

Panoramic photo over 180 degrees inside of the quarry

The old quarry was chosen as the site for the reservoir due to its proximity to the conduit. The abandoned quarry was also a desirable place to build a reservoir as the earth had already been removed. The quarry dates back to the 1860s.

Today, the quarry is plainly visible a few steps from the balancing shaft. There is a short path the goes into the horseshoe-shaped quarry where the hiker can see the chiseled rock all around. There are also remains of a fire pit in the quarry.

Mapping the Balancing Reservoir

The balancing reservoir area as seen on the Strava basemap.

OpenStreetMap is a map that anyone can edit. The data it houses can be downloaded by anyone as well. I enjoy adding data about parks and trails, mainly because others can use that data to plan hikes or trail runs via sites like Strava and GaiaGPS. These sites use OSM data to power their routing tools and maps.

The Balancing Reservoir area is covered by trees and does not look like anything special on aerial photos. Trails in the woods are challenging to map by tracing aerial photography. There are two methods that I use to add trails and other features to the map that are typically obscured by trees: LiDAR and GPS tracking.


Lidar is a technology that uses laser light to measure the elevation of a surface, typically ground elevation. LiDAR datasets are enormous in raw form, so they’re often rendered into map form for viewing. The State of Maryland publishes shaded relief maps for each county in Maryland on the state’s IMAP open data portal. The data is free from license and accessible to all at no charge.

The balancing reservoir stands out as a chiseled area in the center of the image

Based on the lidar, leaf-off aerial photography, and an old plan sheet for the balancing reservoir, I was able to identify the location of the shaft, spillway, dam, and quarry quite quickly. The surface of the earth does not tend to change drastically over the timespan since the reservoir was in operation. Additionally, moving dirt around is an expensive endeavor, so we can expect that the balancing reservoir will remain intact unless it becomes a grave concern to the public.

1:2000 scale shaded relief map showing the components of the balancing reservoir and the approximate location of the 1881 conduit


Some paths and trails are visible on the shaded relief map and aerial imagery. I added the paths that I could see on these maps, but ultimately a ground-truthing expedition was required add all of the balancing reservoir features.

I set out on a short hike to verify and photograph the balancing reservoir site facilities. While walking, I recorded my position with GaiaGPS on iPhone, and with a Garmin VivoActive HR watch. After the hike, I saved the GPS data from Gaia and Strava and loaded it into the JOSM OpenStreetMap editor for input into OSM.

The paths and features added to OSM via JOSM

Back on the computer, I brought in the GPS data (in the form of GPX files) and photos to JOSM. Switching between the lidar and regular imagery layers, and using the photos and GPS data for reference, I added the paths, cliffs, and spillway to map. The Lidar-based shaded relief map is especially helpful in this endeavor, as the spillway, dam and cut lands are plainly visible.

A static map showing the balancing reservoir on the default OpenStreetMap layer

Exploring the Balancing Reservoir

Static preview of an interactive map I made to show the locations of the trailheads and paths leading to the balancing reservoir

There are three points of entry to the balancing reservoir site, marked as trailheads on the map. The Lime Kiln trailhead is temporarily closed for renovations (as of December 2016). The Greenhouse Path trailhead is better for accessing the area from the Willow Grove Nature Center area, while the Sycamore Path trailhead is better for accessing it from the Loch Raven Drive area.


Special thanks to Ronald Parks for his insight into the history of this area. Ronald has published two books that document the history of the Loch Raven Reservoir and maintains a blog about the Baltimore City water system as well.

Thanks to the Baltimore County Department of Recreation and Parks and the Cromwell Park Council for publishing inspirational maps and other information on the Cromwell Valley Park website.

Maryland and Pennslyvania Railroad Abutments East of Towson

The Ma & Pa route

One of my many interests is the study of old and abandoned railways. The Maryland and Pennsylvania Railroad is one of my favorites because it ran through many places I’ve called home. There is a Ma&Pa Railroad abutment located in the woods east of Towson that I hiked to and wrote this article about.


The Ma & Pa as it was affectionately known, ran from Baltimore to Harrisburg via Bel Air, as seen in the timetable map on the right.

If a local government had snatched up the right of way after the Ma & Pa declared bankruptcy in the middle of the last century, it could have been an extreme transit right of way in the current one. Sadly, planners let this one go, and now there is no rail transit to Towson, nor is there a rail link to bustling Bel Air and Baltimore.


Working in Towson has got me interested in how this railway traversed it. There are two stone abutments on York Road near the intersection of York and Towsontown Blvd, which stand tall as reminders of this rail line. Traveling east, however, the path is not as clear.

By the time I-695 (the Beltway) was planned, the Ma&Pa was already nearly dead. Building the Beltway interchange at Cromwell Bridge Rd and Loch Raven Blvd required an immense earth moving project because of the ridge that runs east and west across the county. The Ma&Pa tackled this feature head on by steaming uphill to Towson and then staying on the top of the ridge. Since the beltway had to be a loop, State Roads Commission engineers had to cut through the ridge, and they chose this location.

There once was a gap in the ridge right around where Loch Raven Boulevard and Cromwell Bridge Road meet today. That gap was smaller in those days and contained a stream, the bed of Cowpens Road, and a large trestle on which the Ma&Pa rode. When the beltway designers chose this area to run the road through, the trestle had to go.


SRC Right of Way Plat 10609

The plat above tells the story of what became of the railroad trestle at this location. The beltway and an upgraded Loch Raven Blvd would forever change the landscape. However, some evidence of this trestle remains today, and there could be more to be found.

Ma&Pa Railroad Abutment Hike

On a hot Tuesday in July 2013, I hiked up the ridge south of Loch Raven High School looking for an abutment there, with a friend. Here’s a rough GPS trace of that trip. Right where I thought it’d be, we found a large stone abutment, still largely intact and unaltered. After taking a few photos, we hiked back down to the car and called it a day.


Later, I produced two maps of the abutment as well as places to look for other ones. Some of the areas are vastly overgrown with shrubs and weeds, so I may have to return in the winter. I’m curious whether certain other abutments survive, and what, if any, evidence there is in the triangle between Loch Raven Blvd, I-695, and Cromwell Bridge Rd.
Update 19 Nov 2015: Updated links.
Update 22 Dec 2016: links and content

Map of All MTA Maryland Stops

When I’m not riding the bus, I’m making maps. It is what I do for work (and sometimes fun). I produced a map of every MTA Maryland transit stop. These could be rail, metro, MARC, or bus. I used Google Refine to clean up the data and Carto to map it!

Zoom into Baltimore or Washington and pan around. The number of stops is staggering (although routes don’t use every stop). Click a point to see more details.

Technical Notes

The data are sourced from the GTFS data exchange.

I brought the stops file into Google Refine and ran a whole bunch of transformations to fix things like case, abbreviations, spacing, and formatting. Many of the stops had abbreviations like F/S (far side) that are not clear, so I spelled them all out. Google Refine lets you manipulate massive data sets like this (6228 records) easily! Next, I exported that data and pulled it into Carto.

Getting to the MVA

I sold my car and wrote this story about the trip from Towson to the MVA in Northeast Baltimore to return my registration tags.

Slow Progress

I left work at around 1:30 pm so that I could get down to the MVA before it gets too crowded. Well, by 2:30 pm I was only on the corner of York and Northern Parkway. I could have walked down here in less time than it has required thus far.

The 8

My starting bus stop in Towson. As of 2016 this stop has been moved.

Route 8 is busy. It goes from Towson to downtown via York Road and then Greenmount, and then across one of the city arterials to University of Maryland Hospital. The bus I rode on was an articulated bus, aka bendy bus, which is a testament to the route’s popularity. It stops at practically every corner along the route, though, so it can take a while to get where you need to go.

The 44

Eventually, the 44 did come, around 2:45 pm. That bus was an older model and was full; standing room only. I stood near the rear doors until we got to Sinai Hospital, where many people got off. Besides being full, the drive was otherwise uneventful.


I arrived at the MVA and did what I needed to do. After returning the tags, I looked at options to get home. Maryland Department of Transportation built the newest MVA facility near the Baltimore Metro Subway, and I elected to take that home. The Metro is great. It took less than 20 minutes to get from Northwest Baltimore to the Johns Hopkins Hospital stop. I support any future expansions of this system!

The Metro

The Metro Subway is known for its exceptionally thoughtful station design. Here are some pictures I took during my trip.

Leaving the Johns Hopkins Metro station, I walked through the hospital campus to Wolfe Street and then boarded the 13 Fells Point home.

Rescheduled Routes

I learned an interesting nugget of information from the 11 bus driver today!

Sometimes the bus destination indicator (right above the windshield) will indicate something other than the normal destination, e.g. “11 ARENA” instead of “11 CANTON”. (See picture)

Confused as to why this might be, I inquired with the driver. I learned that when many buses are running late, system-wide, dispatch can alter their routes so that they give people the opportunity to get downtown, and then get on another bus that isn’t late. Otherwise you’d have busses from the same route running practically on top of each other.

Route 13

Today’s ride home proved to wild journey on Maryland’s MTA Local Bus System. I ended up traversing some very sketchy areas, surely frightening poor Meredith, and despite my VFW status, I must admit I was scared at times. I sometimes think having a CCW wouldn’t be such a bad thing.

My typical route home is taking the MTA Route 11 from Towson to Canton. That bus travels down Charles St for its entire length practically and then on down to Canton via Pratt / President / Fleet / Boston. Normally it takes about an hour and a half to get home. Sucks but its cheap and I catch up on audiobooks. On Orioles / Ravens days however, this can become a 2.5-3 hour ordeal as busses don’t fare well in downtown gridlock.

Today I opted to take the mighty 48 quickbus, and would transfer to the 13. Somehow we got stuck with a bus from 1999 that was on its last legs. The 48 goes straight down York and then onto Greenmount through some fairly rugged areas. I don’t mind that stretch though. I was just chatting with the driver the whole time about the Red Line and BRT vs LRT vs HRT. I was solicted by the gentleman next to me for some $3 bootleg DVDs. The labels were printed on an injet with no red ink left.

At Greenmount and North Ave I had to get off and wait for the 13. If you don’t know this corner, its a fairly rough spot. All you can see around are vacant homes, burned and boarded, some convenience stores, and Greenmount Cemetery. Not a good place to hang at night. Anxious to get home (and out of the ghetto) I jumped on the first 13 bus I saw, but it was the wrong one. Uh Oh…

I ended up getting on the 13 to Patterson Park Ave. Which terminates at the scenic [sic] corner of Patterson Park Ave and Federal (see map). This is the 1600 block of Patterson Park, not at all nice. The driver ditched the bus and said she’d be back in a few minutes. Unsure of what to do, I figured I’d just walk on down Patterson Park Ave (through some of the most troublesome east side ghetto neighborhoods) on down to the Park, and then home. Here’s a map of where I got off the bus.

View Larger Map

Not a good plan. I quickly realized that I was much further north of the park than I realized. Over a mile in fact, and I also realized at this point that walking down this stretch of road wasn’t a great plan. I had my iPhone on me and could have charted a different path, but I was anxious about pulling out the iPhone in that area. I always think it’s better not to show the gadgets in an area where you might be targeted for armed robbery. Here’s one of the blocks I walked by:

View Larger Map

I kept walking though. I made it as far as Monument before Meredith finally came and picked me up. Thank goodness! The streets were really starting to deteriorate and I was becoming wary of some kids that seemed to be following me. I called some friends that work in those police precincts later and confirmed I was walking straight through some of their most problematic areas. Glad I’m home.

I learned today that there is a lot more of Baltimore than most of us know, as we zoom by on the beltway or 95. Taking the bus really can inject you right into the veins of some Baltimore slums that are reminiscent of Tikrit. I also learned that reading those bus signs is important, and on Game Days I should probably drive.

Hope you’ve enjoyed my story.