After :
Quail Creek, a tributary to the Gunpowder River in Baltimore
County, was damaged by the failure of a regional stormwater management
pond which breached during a 5-inch rainstorm in 1989. The drainage area
at the pond is 500 acres. The stream had hosted a trout population three
years before the failure. One month after the failure, surveys by the State
Department of Natural Resources showed that no young trout were present
and the macroinvertebrate population had declined to a few diptera (a very
tolerant form of two winged fly).
Brightwater was hired by the developer who had been given an enforcement order requiring him to restore the stormwater management facility and the stream. Brightwater designed the restoration plan and negotiated with the agencies for permit approval. The design effort was the minor part of the work, since the restoration plan called for heavy equipment to work in the stream channel. Prior to this work, permit conditions had always prohibited this in Maryland. The design took three months to develop and permit negotiations took another year. The actual construction was done by Dave Rosgen, with Brightwater providing support and construction management services. The restoration project was completed in August of 1990.
Brightwater has conducted monitoring of the stability, particle size distribution of substrate, water te~mperature, fish and macroinvertebrate populations for six years. Permanent cross sections were installed and surveyed annually, and pebble counts were conducted annually. Aquatic macroinvertebrates and fish were sampled each year. Recording thermometers were installed to record thermal effects of the stormwater management pond. The results of this monitoring show a recovery of fish and macroinvertebrate populations, a shift in particle size distribution from a dominant size of sand less than two millimeters up to 64 - 256 millimeters. The restoration work is stable and vegetation has recovered enough to provide the permanent stabilization on banks where root wad revetments were installed. One of the surprising things discovered on Quail Creek was the relationship of sediment generated from an input of excess sediment into a stream channel. The quantity of sediment that entered Quail Creek during the failure of the pond was 120 cubic yards. This input initiated accelerated bank erosion which resulted in more than 3,000 cubic yards of new sediment being generated in the first year before the restoration work was done. The restoration work has arrested that process and allowed the system to recover.