PARENT SESSION
Oral Session #82: Urban Ecology.
Presiding: M. Cadenasso
Thursday, August 8. 9:00 AM to 11:30 AM. Grand Ballroom East, Radisson.

Bonita creek - Ecological restoration in an urban setting.

Griswold, Margot^*,1, ¹ Earthworks Construction & Design, Los Angeles, CA

ABSTRACT- The restoration of lower Bonita Creek and its adjacent upland in the city of Newport Beach, Orange County California presented several challenges for ecological restoration in the urban setting. In the conceptual design phase, the reconstructed creek was to designed with a low flow channel and an underground box culvert to divert high flows over that of a 10-year storm event for flood control. Through a watershed analysis and a series of hydrologic models and site evaluations, the final restoration plan was developed for lower Bonita Creek. In the final design and implementation, ecological criteria prevailed and the high flow box culvert was deleted and natural flows were retained throughout the restored creek. The plant palettes specified in the conceptual plan were modified to reflect the changes in the final design of the creek. Based on the results of the watershed analysis, surface flow models, soil moisture tests, and the micro-topography of the site after finish grading, the layout of species in each habitat type was determined. The density of plants per acre suggested in the conceptual plan was reduced to encourage natural recruitment and to limit competition for nutrients and water to establish healthy, self-sustaining plants. Adjacent upland slopes were restored to coastal sage scrub habitat. Results are presented for the development of the vegetation and wildlife use of the site after six years. The evaluation of the hydrologic, biogeochemical, and biologic conditions of the site indicate a functioning riparian habitat and adjacent upland buffer in an urban setting. The site is part of a bike and trail system for Orange County. Tours of the site are geared to educate the public about local ecological restoration.

KEY WORDS: ecological, creek, upland, restoration