Double Rock Park Stream Restoration Project

The Double Rock Park stream restoration is a pilot project for the Baltimore County, Maryland, Stream Restoration Program. The study assessed watershed conditions and the stream channel stability of Stemmer's Run and its tributaries from the downstream boundary of Double Rock Park to its headwaters. Double Rock Park is a highly utilized public recreation facility with unique physiographic features that include waterfalls which are uncommon in eastern Maryland. The objectives of the study were to diagnose the causes of stream bank erosion, and to recommend stream and watershed restoration strategies within the 754 acre watershed draining to the park boundary. The paper presents a methodology for diagnosing causes of the stream bank erosion through the use of the Rosgen Stream Classification System, a system of classifying stream channels by delineative criteria which integrate the eight variables which shape and maintain channels. The methodology includes at assessment of how the channel handles stress during frequent high flows based upon its width-depth ratio, slope, confinement, the size and cohesiveness of the materials in the active channel, vegetation on the banks and its depositional state. A method of evaluating the equilibrium between channel size and flow regime is also presented. The results of the analysis are used in the design of a stable channel configuration. Stream restoration concepts are specified for reaches of Stemmer's Run. The goal at each site is a stable stream type having the capacity to convey frequent high flows, the competence to transport sediment delivered from the watershed, and a dramatic reduction of sediment from bank erosion.