Restoration Recommendations for Fish Species Re population of Strawberry Creek based on High Flow and Stream Habitat Assessment Cheryl Lee Abstract Strawberry Creek is an urbanized creek that is in the process of being restored However the final step of re populating the creek with fish has not been as successful as planned One proposed theory for the failure of these attempts has been the lack of high flow refuges To address this possibility flow patterns were observed and diagrammed during times of high flows at various sites along the creek on the U C Berkeley campus High flows are flows caused by rain storms resulting in higher than normal flows Habitat assessment was also a concern thus creek characteristics of depth width bank angle undercut vegetation overhang sediment type bank development creekside vegetation and flow were measured Flow was measured at times of normal or base flow as well as at times of high flow Six different sites of Strawberry Creek on campus were observed and assessed for flow and habitat characteristics based on observations and previously documented criteria to make larger scale restoration recommendations Flows were found to vary significantly between base and high flow conditions Additionally it was found that there are very few high flow refuges in Strawberry Creek This in addition to mostly unfavorable habitat characteristics leads to a wide range of restoration recommendations However implementation of such recommendations are limited due to the highly urbanized nature of the creek Ideally restoration should include the reduction of channelized sections and or banks as well as the planting of more vegetation along the banks Other recommendations which may not be as feasible would be to create more meanders or variations on ox bow to give fish areas of reduced flow Introduction Strawberry Creek on the University of California Berkeley campus has been an integral part of the university s long history The current site of the campus was originally chosen because of the presence of Strawberry Creek Willey 1887 However over the years the creek has been modified and degraded due to the urban impacts and influences of the campus and surrounding areas These impacts have led to poor water quality lack of flora and fauna and threatened structures due to bank erosion Finally in 1987 these concerns were addressed by the University to create and implement a management plan for Strawberry Creek Charbonneau 1987 The plan has been implemented in several aspects and has treated many of the problems the creek faced Restoration efforts have included sewer and sanitary system repairs bank stabilization check dam repair and installation regrading slope stabilization and revegetation These efforts have led to improved water quality and the return of several biological communities Charbonneau and Resh 1992 The next step in the restoration process is the reintroduction of several fish species However these efforts have not experienced their anticipated success Kondolf pers comm One reason of the lack of success may be the extreme urbanization of the Strawberry Creek watershed About 40 of the 470 ha watershed is urban and characterized by extensive areas of impermeable surfaces such as parking lots buildings roads and irrigated lawns The added impermeable surfaces create more run off which leads to increased flows since less water is able to permeate into the ground These factors combined with culverting channelization and storm water routing create a hydrologic regime where peak storm flows are higher than preurbanization conditions Charbonneau and Resh 1992 Charbonneau 1987 Impacts of channelization on habitat for fish and invertebrates include removal or subsequent loss of riparian vegetation loss of instream cover snags altered riffle pool sequence decreased stream sinuosity altered substrate composition increased stream velocity increased bank erosion and bed scour increased suspended sediment and increased water temperature Crandall et al 1984 These factors lead to the idea that perhaps the winter storm flows flush the fish populations out thus preventing them from establishing themselves High flows or flushing is detrimental to the fish if they are unable to tolerate the increased water velocities The intolerance of higher flows can lead to the fish being eliminated from the stream Nunnally 1978 Another possibility is that the fish are flushed downstream by the high flows but not eliminated from the stream Yet both of these consequences are still counter to the goal of fish re population in the desired stretch However the flushing might be avoided if there are high flow refuges for the fish populations Yet the presence of high flow refuges has yet to be documented for Strawberry Creek although the issue has been considered for the creek and other restoration efforts Kondolf pers comm Flow refuges not only offer areas or retreat for energetic savings but also offer opportunities for enhanced feeding and migration Gerstner 1998 It has been shown that areas of high flows have reduced predation on macroinvertebrates Hart and Merz 1998 The lack of predation or potential food for fish species is another reason why refuges are essential It has been found that the availability of flow refuges is a critical habitat factor for brown trout and grayling species Maki Petays 2000 These refuges have been found to be essential during the winter Vehanen 2000 Additionally during times of high flow these species were more susceptible to downstream displacement in channelized streams Maki Petays 2000 Refuges provide a number of benefits for fish They should provide protection from swift currents high temperatures and predators Garcia De Jalon 1996 One way these qualities can be attained is having areas of adequate cover Cover may be in the form of riparian vegetation undercut banks aquatic vegetation and rubble boulder areas Debris jams may also form refuges and pools Reiser and Bjornn 1991 Plunge pools can offer additional refuges due to the increased dissolved oxygen levels and depth Fitzgerald 1998 Another high flow refuge could result from in stream large woody debris which has many other stream altering benefits Kondolf 2000 Other consequences of refuge areas should also be considered While debris jams may form beneficial refuges they could become sediment traps Reiser and Bjornn 1991 Another effect of refuges could be increased pool formation or flooding which is a drawback
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