As previously discussed, urbanization of the watershed has had profound effects on Strawberry Creek. Continued development will create additional impervious surfaces that will further increase runoff and peak flows into the creek drainage system. This could pose both a flooding and erosion hazard to the central campus area if enough impervious surface was added. Due to these considerations, a full buildout scenario was constructed based on future development projections for the University, LBL, and North Berkeley.
At the present time, the upper Strawberry Creek watershed encompasses about 137.2 areas (78%) of the total central campus area of 177 acres. Impervious areas on the central campus consist of buildings, roads, parking lots, walkways and turf areas. Turf areas are considered impervious because they are at or near saturation due to irrigation, and during heavy rainfall these areas will quickly become saturated, resulting in excessive surface runoff. At this time, approximately 105.2 acres (77%) of the central campus watershed area is comprised of impervious surfaces. Table 7 presents a breakdown of the existing and proposed amounts of impervious areas by their respective subwatersheds.
The southwestern section of the central campus drains directly into the Main Branch of the creek. This small subcatchment area has a higher percentage of impervious surface than the rest of the campus because of the large relatively impermeable turf areas at Evans Field and Edwards Track Stadium whose drainage is routed into the Main Branch. Table 7 shows no net change in the amount of projected impervious surface in the central campus watershed. Future development on the central campus will add a minimal amount of impervious surface because almost all the sites being considered are already impervious areas such as parking lots. The relatively small amount of additional impervious surface added can be offset by the replacement of the Agriculture parking lot and the temporary buildings in the Central Glade with previous landscaping. The amount of previous landscaping will depend upon the extent of additional impervious turf areas placed in these areas. If relatively little turf is used, these additional landscaped areas will off set the impervious surf aces added by projected development on the central campus.
According to the UC Campus Planning Office, the following projects and potential construction sites within the central campus creek watershed are either currently being considere4 will be considered in the future, or are already under construction:
- Genetics/Plant Biology buildings and parking structure under construction between Morgan and Warren Halls.
- Future Chemisrry building in parking lot #48 west of Latimer Hall.
- Future Student Services building in the vicinity of Building T-4. Plans are to remove all the temporary buildings and landscape that area.
- Future underground expansion connecting Moffitt and Doe Libraries. Some previous areas will be removed and replaced by a roof structure.
- Future Business School building at the present site of Cowell Hospital. Cowell will be either renovated with an addition on the east site or demolished.
- Agriculture parking lot (#1) will be removed and the courtyard areas between Giannini, Wellman, and Hilgard Halls restored.
- New building to replace Callaghan Hall.
- Future potential development site at North Gate parking lot #66 on Observatory Hill.
- Future potential development site at Stanley Hall parking lot #80.
- Future potential development site at Dwinelle parking lot #20.
- Future potential development site at Hellman Tennis complex north of Edwards Track Stadium.
- Future additions to Morrison and Kroeber Halls.
- Tentative future development site at Haviland Hall parking lot #41.
Other potential University development sites being considered in the rest of the watershed include:
- Addition to Bowles Hall
- Future Computer Science building at parking lot #26 between Etcheverry Hall and Le Roy Street (N orthside).
- Botanical Garden parking lot opposite the LBL gate on Centennial Drive.
- Possible additions to the north and south sides of the Lawrence Hall of Science.
- Additional parking lot above the Lawrence Hall of Science off Centennial Drive.
- Hill Housing student resident complex along La Loma A venue.
- Future addition to the north end of Stem Hall.
- Future limited expansion in the area of the Math and Space Sciences buildings.
- Possible utilization of the Animal Behavior Research Station as a future development
No plans yet exist for these projects so it is speculative as to how much impervious surface these projects will add. It is esJ:imated that about 3.2 acres of impervious surface will be added by these projects assuming that the Animal Behavior Research Station is not developed. All of these sites except the Botanical Garden parking lot (about 0.5 ac.) will drain into the North Fork subwatershed. This amount of development should not significantly affect the hydrologic regime of Strawberry Creek.
According to the LBL Long Range Development Plan of 1987, there is a projected 4% increase (6.1 acres) in the amount of impervious surface added to the LBL complex over existing conditions. Currently, 49.5 acres (38%) of the 129.7 acre facility consists of impervious surfaces such as structures, roads and parking areas. In the future, this is projected to increase to 55.6 acres (42%) of impervious surface in an expanded site of 133.4 acres. Open space within the complex will diminish from 80.2 to 77.8 acres, or from 62% to .58% of the total area. Of the projected 6.1 acre increase in the total amount of impervious surface at LBL, approximately 4 acres will be located at the Life Sciences Research area at the eastern end of LBL north of the Botanical Garden. This area drains into the South Fork of Strawberry Creek and should not significantly affect its hydrologic regime.
According to the City of Berkeley Planning Department, no significant development plans are currently being considered for the area of North Berkeley within the watershed. It appears that the residential areas bordering University and LBL property are at or near full buildout potential.
Based on this analysis, it is estimated that about 4.4 acres of impervious surface could be added to the North Fork subwatershed, whereas 4.6 acres could be added to the South Fork subwatershed in the foreseeable future. This relatively small amount of additional impervious surface should not significantly impact the hydrologic regime of the creek drainage system. However, the cumulative impacts of continued development in the future will likely prcxluce deleterious effects over the long term. In the near future it is possible that some accelerated streambank erosion may occur in the unnamed branch of Strawberry Creek west of the Botanical Garden and in the North Fork channel on the central campus, as these channel reaches will bear the brunt of the additional storm runoff from the projects previously outlined.