The Bull Run Hydroelectric Project was a PGE development on the Sandy River basin near the town of Sandy, Oregon.  Originally built between 1908 and 1912 by the Mt Hood Railway and Power Co.,  it supplied hydroelectrical  power for the Portland area for nearly a century, until it was removed in 2007 and 2008. The project used a system of canals, tunnels, wooden flumes and diversion dams to feed a remote storage reservoir and powerhouse. The entire project was removed because of rising environmental costs, lack of fish ladders and diminishing hydroelectrical returns. Marmot Dam on the Sandy River was demolished in 2007, and the Little Sandy Dam on the Little Sandy River was taken down in 2008.

Roslyn Lake

 The storage reservoir was called Roslyn Lake.  It had earthen walls which formed a 10-foot high berm around the entire lake.  The lake covered 160 acres and had a max depth of 27 feet.  It was fed by the flume from the Little Sandy River Dam.  The lake had a variety of campgrounds, picnic areas and docks for swimming.  It was regularly stocked with trout.  I have been unable to find how the reservoir got the name Roslyn Lake.  But I do have a theory:  The reservior adopted the name Roslyn Lake in 1925.  At this same time, a Portland City Commissioner named John M. Mann owned a 150-acre ranch near the lake called Roslyn Lodge.   He would have parties and event gatherings there sometimes.  It's likely that Commissioner Mann used his ranch's namesake when the name was changed from Bull Run Reservoir to Roslyn Lake.  It was changed because people were getting Bull Run Reservoir confused with Bull Run Lake 30 miles upriver.


 The lake was drained and dried up in 2008.

Roslyn Lake 2013

 Pictured above is a view of Roslyn Lake.  This shows the powerhouse (white building lower left). The lake and the powerhouse were connected by the 2 flowtubes or penstocks.  This picture gives an idea how much force the water would have charging down the steep hill to the powerhouse turbines.  The lake sat 320 feet above the powerhouse.

The entire hydroelectric project started here at the Little Sandy River.  Here a dam was placed which diverted the water to a 3 mile long wooden flume. The dam was 16-feet high and used the entire river turning the downstream river into a dry riverbed.  No fish ladders were needed here because the lower river was completely compromised.  This flume emptied into Roslyn Lake. From Roslyn, it traveled a short distance down a steep hill to the powerhouse where the turbines were.  After wards, the water was released back to the Bull Run River. Once this dam was removed, water stopped flowing into the flume and Roslyn Lake no longer had a water supply.  

The flume was 3.2 miles long and was all gravity feed.  It was built between 1909 and 1912 by hand.  The flume was 14 feet wide and 9 feet deep.  It had rails on top for service cars to run on when men worked on the flume.

Within a year, the plant realized and added more potential with the building of Marmot Dam.  This bigger dam brought water from the neighboring Sandy River and "bumped up the volume" of hyrdoelectric power produced.  Marmot dam was 47 feet high and was made from concrete.  The water traveled down open canal and thru several underground tunnels and was dumped just in front of the Little Sandy River.

Below, you can see a diagram of how the rivers, tunnels, canals and flumes interconnected to bring water to the impoundment reservoir above the Bull Run powerhouse.

In 2008, the lake was drained and the surrounding dikes were pushed into the lake bed making the area more level.  Canals and tunnels connecting the Sandy to the Little Sandy river were filled in.  Concrete troughs and spillways were removed.  The wooden flume was cut into pieces and air-lifted piece by piece out by helicopter.  The old lake bed was used as a staging area for this.  Most of the project was removed to allow nature to grow over and cover it.  On Phelps road, where the flume used to cross, there remain concrete footings that trace the flume's path.  Roslyn Lake park still exists.  The Bull Run powerhouse is being restored as a museum.

Bull Run Hydroelectric Time Line

1906  Planning begins on BRHEP

1908  Construction on LSRD and flume begin

1912  Little Sandy River Dam completed

1912  Bull Run begins generating power
1912  MHR & PC merges with PRL & PC (PGE)

1913  Marmot Dam completed
1925  Bull Run Reservoir renamed Roslyn Lake

1989  Marmot wooden crib dam replaced with new concrete dam
1999  PGE announces it will remove Marmot dam
2004  Marmot Dam operating license expires

2007  Marmot Dam demolished

2008  Little Sandy River Dam demolished
2008  Roslyn Lake ceases to exist 

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