The 1986 baseline study of the creek coincided with the sixth driest weather year on record in the San Francisco Bay area (EB MUD). Therefore, the creek channels observed to be flowing in the Fall of 1986 can be considered to be perennial channels under most circumstances. Figure 6 shows the locations of the ephemeral and perennial channels in the Strawberry Creek system.
The Strawberry Creek channel passing through the Botanical Garden dries up quickly above the Garden. Flow in this branch is augmented by EBMUD water several times a week from February through December or throughout the year if it is especially dry. This is done to support the goldfish pond in the Rhododendron Dell and for aesthetic purposes. The unnamed branch of Strawberry Creek just northwest of the Botanical Garden along Centennial Drive flows at about 0.005 cfs. This branch is fed primarily from a groundwater dewatering well located at the Animal Behavior Research Station. This well is pumped continuously to prevent landslides in the area that may occur due to saturated soil conditions and the overflow is dumped into the creek channel. DOFM is currently looking at the feasibility of using this groundwater supply for flow augmentation and irrigation purposes at the Botanical Garden. Hamilton Creek was found to be flowing at the rate of about 0.003 cfs out of the upper canyon.
The other perennial channels in the watershed include Chicken Creek and an unnamed creek that drain the central portion of the canyon including LBL. Both of these channels had very low summer flows, about 0.002 cfs. The perennial North Fork drains the northern part of the watershed encompassing most of the LBL complex as well as Lawrence Hall of Science, Math and Space Sciences complexes and extends all the way to Grizzly Peak Boulevard. The LBL stream reaches are culverted underground, making identification of the exact sources of these waters difficult. However, much of this water is drainage from hydraugers (drilled underground horizontal drains) that dewater the hill area around the LBL complex.
Table 5 presents summer baseflow measurements taken in conjunction with the baseline water quality sampling program. This shows that about two-thirds of the Main Branch streamflow came from the South Fork, whereas one-third was North Fork flow. The average combined flow of Strawberry Creek ranged from 0.50-1.13 cfs, averaging 0.89 cfs. The flow in both forks approximately doubled through the central campus due to the contribution of point source effluent.
The point sources on campus contribute a significant volume to the total summer baseflow of Strawberry Creek. North Fork point sources comprise an average of 0.14 cfs, or about 50% to the average low flow streamflow of 0.28 cfs in the North Fork. Point sources in the South Fork also contribute an average of 0.29 cfs or about 50% to the average summer baseflow of 0.58 in the South Fork. Therefore, about half (0.43 cfs) of the average baseflow (0.89 cfs) of the Main Branch of Strawberry Creek is comprised of central campus point source effluent.