ACEC

Deep River Rock Riffle Improvements Project

Firm: Patrick Engineering, Inc.


Other Consultants:


Owner: Little Calumet River Basin Development Commission


Description: Original or innovative Application of New or Existing Techniques Spurred by the need to harness the run-of-the-river for power and industrial cooling by pooling impounded water, hundreds of thousands of low-head dams, ranging up to 15-feet in height, were built across U.S. rivers and streams. The number of dams greatly increased in the 1900’s with the 1960’s and 1970’s being considered the “golden era” of dam construction. However, following the centralization of industry and agriculture, the need for dams ceased, and America’s river landscape became dotted with defunct dams with no societal benefit. Low-head dams are often neglected, and removal or modification is often more economical in the long run. Moreover, and as previously indicated, kayakers, canoers, rafters, boaters, anglers and swimmers are often unaware of the dangerous forces and fast recirculating currents that these dams can produce – creating a significant safety hazard. Therefore, by constructing a rock riffle on the downstream side of the dam, the existing wetlands along the backwater pool are not affected or lost. A rock riffle structure is composed of a stepped pool system, typically built at a 3-5% slope, depending on the space available and the species of fish that will attempt to move upstream through the riffle. Riffles may be closely spaced to create stepped pool channels or spread apart to divide the spacing into runs and pools, typical of meandering channels. Over the last four decades, rock riffle structures have significantly improved river safety, and helped restore river ecology. Future Value to the Engineering Profession and Perception by the Public Today, the impacts and consequences of climate change and global warming can be seen in every aspect of the world we live in. Rivers and wetlands play a critical role in thermal microclimates, carbon storage, flood control, groundwater recharge, and support the diverse habitat for numerous native plants and animal species. However, science shows that dams cause considerable disruption and are detrimental to the ecology of river and wetlands. Dams change the chemical, physical, and biological processes of rivers and backwater wetlands; alter water temperature and oxygen levels; and can trap sediments, which are sometimes contaminated in the backwater area. Sediment pollution is a major contributor to the degradation of aquatic life and its associated habitats. Suspended solids increase the water temperature and lower dissolved oxygen, harming sensitive aquatic animal species. Furthermore, sediment pollution can block out sunlight for aquatic plants, which cover spawning areas and food sources; thereby reducing the populations of animals, such as fish and insects, disrupting the natural food chain and decreasing diversity. Therefore, stabilizing rivers and streams using natural restoration methods, such as rock riffles, has allowed for the free movement, recolonization, and recovery of various aquatic animals. Furthermore, dam modifications encourage diversification of genetics with aquatic species, creating a more sustainable, healthy, quality river environment. Social, Economic, and Sustainable Design Considerations Patrick and our subconsultants completed a riffle design, which removed portions of the sheet-pile dam and installed natural materials in a drop-pool-configuration-type riffle, which allows for fish migration and natural habitat. The riffle structure also serves to increase recreational opportunities and safety, which will attract recreational users to this unique river park. Complexity The residents of Lake Station have a deep affinity for the role that Deep River and the dam played in their childhoods, as well as the recreation opportunities the river provides today. Therefore, it was imperative that the proposed improvement not diminish the culture and identity that so many had adopted. A series of meetings were held with the local community, and action groups formed to maintain the public’s voice as the project moved forward. Furthermore, this area of the river had a history of extensive flooding and no rock riffle of this size had been completed within the State of Indiana. Therefore, the Patrick Team proactively engaged and coordinated with permitting agencies to ensure not only fish and wildlife passage, but also that proposed improvements did not adversely impact the floodplain. Exceeding Owner Needs In its infancy, the Deep River Rock Riffle project started out as just that – a rock riffle. However, stakeholders soon realized that they had an opportunity to truly “Build Back Better.” This project not only restored river ecology and improved safety; but leveraged recreational enhancements to reconnect people to the river’s edge. Improvements included: a new boat ramp; a 220-foot-long bicycle/pedestrian bridge spanning Deep River; 0.5 miles of shared-use paths connecting downtown Lake Station to Lake County’s Three Rivers Park and Belleboo’s Play and Discovery Center; stone terracing for fishing or passive contemplation; and pollinator garden landscaping – dramatically transforming this area of Lake Station.  





Little Calumet River Basin Development Commission