Directions to Horse Canyon :
From Highway 1 going north, make a right on Highland Drive and enter the Cal Poly campus. At the third stop sign, turn left on Via Carta. Continue down Via Carta until you see the Horse Unit on your left and the Ornamental Horticulture Unit on your right. Find parking in this area. Walk past these buildings and you will see the corral behind the Horticulture Unit on your right. Walk through the gate and begin the
Horse Canyon hike.
1 .Horse Corral 4 . Serpentine Outcrop and Power Lines
The walk up to Indonesian Reservoir passes through the horse corrals, which are managed primarily by Cal Poly students.
2 . Indonesian Reservoir
On the opposite hillside from the previous serpentine outcrop is another outcrop, which appears to be more significantly weathered. There is a noticeable vegetation change at the serpentine boundary.
5 . Lower Tributary
Indonesian Reservoir represents the lowest drainage point for Horse Canyon Watershed. The water is pumped into the reservoir as part of Cal Poly's water management plan. From the reservoir the water will be gravity fed to various locations around campus.
3 . Serpentine Outcrop
This is one of the smaller tributaries that serve as draws into
Horse Canyon. During rainy months this tributary will contribute significant amounts of runoff into Indonesian
Reservoir.
6 . Road up the Canyon
Just up the road from the reservoir inlet is a prominent serpentine outcrop located on the east (right) side of Horse
Canyon. Serpentine makes up the majority of the underlying bedrock for this area and is an important factor on the areas hydrology. It also happens to be the state rock of California.
The ranch road is used for access to upper Poly Canyon and is a popular horseback riding trail. At the time this picture was taken the road had just been graded to smooth out arisen channels caused by winter rains. The road is a significant sediment contributor to the Horse Canyon creeks and
Indonesian Reservoir.

7 . Culvert 11 . View of Upper Road
This culvert was intended to divert water from the main tributary under the road and into the main creek channel.
However, since the ranch road is in-sloped all of the road runoff is also diverted into this culvert. The road adds 9.3 acres of watershed area to this already undersized culvert.
Frequently during heavy rains the culvert will plug with debris causing the water to wash over the road.
8 . Road Cut
Canyon.
12
This is the view of the Horse Canyon upper ridge from the main tributary. On the other side of this ridge lies Poly
. Reservoir and Campus
Along the ranch road are excellent road cuts that expose some of the area's soil types. This is a profile of Los Osos soil, which is an older soil commonly found on upland sites.
The Los Osos soil is commonly covered with grassland vegetation and is excellent for grazing.
9 . Upper Tributary
From this view the Cal Poly campus can be seen in the valley. Just behind the campus lies San Luis Mountain.
13 . Horses on Perimeter of Corral
As we finish our hike and look back up to the east a noticeable feature can be seen as a scar on the mountain behind the horses. Cal Poly uses gravel from this site to maintain their ranch roads like the one we just hiked on.
HOPE YOU ENJOYED THE HIKE!
This is the largest tributary to the main Horse Canyon stream channel. The shallow serpentine bedrock during high rain months causes much of the runoff to be in the form of overland flow. This can significantly affect the mainstream discharge.
10 . Old Weir
This is one of the weirs built to study the discharge of Horse
Canyon watershed. Many of the weirs have been filled in with sediment and are no longer functional. Horse Canyon is one of the larger watersheds on campus and it is important to continue monitoring its discharge.