Bass Lake is also known as Crane Valley Reservoir
Click on the picture for a expanded version
||The original dam
was built in 1896 and enlarged in 1910. The Sugar Pine Railroad used to
cross the dam, bringing logging to Fresno. The Dam is actually two
parts both basically earth (Hydraulic Fill).
The long side, the one you see from most angles of the lake has no
spillway. There is a water tower which allows for the regulated outflow
to the generator and stream.
|The other side is around to the East. It
is where the spillway is located. The spillway is specially designed to
allow high levels of water to flow down stream without damaging the
spillway has 2 moveable gates to regulate outflow. The height of
the Spillway to the top of the gates is about 11.5 ft. The top of the
gate is 3376.4 ft elevation.
|Here you see the steel tracks for the removable boards. The boards slide into a track and hold water
back. They are installed after April 1st and remove November 1st. They can not be removed when holding back water. Typically no water goes through the spillway since it cannot be used
to generate power. The spillway provides emergency protection to the dam. All outflow is regulated through the power station.
||The Boards and the Gates are closed in this picure taken with the lake filling and only 3" of water pushing against the boards.
Take a Hike!
The Dam is accessible from the public boat ramp on the South
East side of the Lake from Road 222. You can walk across the long dam,
follow the paved road a little further and you will see the Spillway.
If you follow the paved road for 10 minutes you will meet Road 274 and
see Browns Ditch, or reverse the path and start at browns Ditch.
Along side the Falls are trails on both sides. They will take you up
the creek to where Road 274 crosses. The trails go up at least another
mile. Beware of poison oak. Be in shape because it is a steep climb.
of the rain and snow melt, run into the lake through the Falls located
at the North West end. North Shore Road (rd 432) crosses over this
creek called 'North Willow Creek' This creek is also the source of drinking water for the Pines Track & Falls Tracks
is Browns Ditch. This slue was added to increase the inflow when the
dam was enlarged in 1910. The slue is located at the North Eastern side
Lake. You can see Browns Ditch on Road 274 & Central Camp.
Water fills the slue at a maximum rate of 75 cu/ft/sec from Browns
Creek and South Willow Creek along with several other unnamed creeks.
|Many smaller streams also feed water to the lake.
Willow Cove - Pines Creek
Lake Shore Cove - Salter Creek
Recreation Point - Slide Creek
Crane Valley Power House, at Bass Lake has a 900 KW Generator,
installed in 1919. This is one of 5 generators on the San Joaquin
River system producing about 28 MW's of power
power House as seen from the top of the dam. Water is diverted to
either the creek or to another slue taking it to other
generators. Water is always released into the creek to maintain
the down stream habitat.
Dam Operation and DescriptionThe Lake is
Owned by PG&E and regulated by government agencies.
PG&E operates the lake under a Federal License which sets the
conditions for maintaining the lake's water level and outflow needs.
Considerations are made for the following uses:
Flood Control & Lake Level
This needs are obvious. As summer ends the lake level is lowered to
60% of capacity to about -25 ft. Regulations require the Lake to be lowered to 60% of capacity by September 15th and 50%
by November 1st. The Bass Lake Homeowners Association and other
community interest lobbies
PG&E to request a waiver of the rules delaying the draw down. This
waiver is granted if a number of conditions exist to assure the lake is
lowered to required levels. PG&E also schedules a maintenance
outage to service all the power stations and slues in the system. This
outage usually occurs in July & August so the ability to draw
down the lake is limited to
providing water to downstream habitat. Over the past few years the lake
level has been kept high enough to keep docks floating through Labor
Drink Water Supply
The Lake provides limited drinking water to the PG&E Camp site
area behind Millers Landing. Bass Lake Water District draws water from
the stream feeding the falls. Other homes and tracks obtain well water.
Down Stream Habitat
It is not possible to cut all water out flow down stream without
damaging the habitat. Water supports fishing and wild life. It is not
wasted however since down stream dams also generate power. Water
flows into the central valley and is used for drinking and
Crane Valley Powerhouse, sited immediately below
Bass Lake Dam generates 900 KW of power through its turbine and after
the water is discharged from the powerhouse, it continues through four
more down stream powerhouses generating about 28 MW for the
system. From the top of the dam you can see the powerhouse
and the water moving down stream. Power is generated when ever the lake
is drawn down for any reason. Sometimes energy needs out weigh the
recreational needs to keep the lake full.
The Lake brings thousand of people to the area and make a
significant contribution the the area's economy. The government and
PG&E do there best to maintain the lake's condition including
keeping the water level high enough during the summer.
|Dam Information |
||Dam Name||Crane Valley
||Quad Name ||BASS LAKE
||Material Volume||907,000 cu yd
||Storage Capacity||45,410 ac-ft
||Reservoir Area||1,165 acre
||Drainage Area||51.4 sq mi
|Crest Elevation||3,380.86 ft
||Crest Length||1,880 ft
||Crest Width||40 ft
|Total Freeboard||14.80 ft
||Operating Freeboard||4.1 ft