A fish ladder, also known as a fishway, fish pass, fish steps, or fish cannon, is a structure on or around artificial and natural barriers (such as dams, locks and waterfalls) to facilitate diadromous fishes' natural migration as well as movements of potamodromous species. [1] Most fishways enable fish to pass around the barriers by swimming and leaping up a series of relatively low steps (hence the term ladder ) into the waters on the other side. The velocity of water falling over the steps has to be great enough to attract the fish to the ladder, but it cannot be so great that it washes fish back downstream or exhausts them to the point of inability to continue their journey upriver.
Written reports of rough fishways date to 17th-century France, where bundles of branches were used to make steps in steep channels to bypass obstructions.
A 1714 construction of an old channel bypassing a dam, "originally cut for the passage of fish up and down the river", is mentioned in the 1823 U.S. Circuit Court Case Tyler v. Wilkinson. This example predates the 1880 fish ladder at Pawtuxet Falls. The 1714 channel "wholly failed for this purpose" and, in 1730, a mill was built in its place. The channel and its mill usage became an important legal case in U.S. water law. [2]
A pool and weir salmon ladder was built around 1830 by James Smith, a Scottish engineer on the River Teith, near Deanston, Perthshire in Scotland. Both the weir and salmon ladder are there today and many subsequent salmon ladders built in Scotland were inspired by it. [3]
A version was patented in 1837 by Richard McFarlan of Bathurst, New Brunswick, Canada, who designed a fishway to bypass a dam at his water-powered lumber mill. [4] In 1852–1854, the Ballisodare Fish Pass was built in County Sligo in Ireland to draw salmon into a river that had not supported a fishery. In 1880, the first fish ladder was built in Rhode Island, United States, on the Pawtuxet Falls Dam. The ladder was removed in 1924, when the City of Providence replaced the wood dam with a concrete one. USA legislated fishways in 1888. [5]
As the Industrial Age advanced, dams and other river obstructions became larger and more common, leading to the need for effective fish by-passes. [6]
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Fish ladders have a mixed record of effectiveness. This varies for different types of species, with one study showing that only three percent of American Shad make it through all the fish ladders on the way to their spawning ground. [21] Effectiveness depends on the fish species' swimming ability, and how the fish moves up and downstream. A fish passage that is designed to allow fish to pass upstream may not allow passage downstream, for instance. [22] Fish passages do not always work. In practice a challenge is matching swimming performance data to hydrodynamic measurements. [23] [24] Swim tests rarely use the same protocol and the output is either a single-point measurement or a bulk velocity. In contrast, physical and numerical modelling of fluid flow (i.e. hydrodynamics) deliver a detailed flow map, with a fine spatial and temporal resolution. Regulatory agencies face a difficult task to match hydrodynamic measurements and swimming performance data.
During the last three decades,[ when? ] the ecological impact of culverts on natural streams and rivers has been recognised. While the culvert discharge capacity derives from hydrological and hydraulic engineering considerations, [25] this results often in large velocities in the barrel, which may prevent fish from passing through.
Baffles may be installed along the barrel invert to provide some fish-friendly alternative. [26] [27] [28] For low discharges, the baffles decrease the flow velocity and increase the water depth to facilitate fish passage. At larger discharges, baffles induce lower local velocities and generate recirculation regions. However, baffles can reduce drastically the culvert discharge capacity for a given afflux, [29] thus increasing substantially the total cost of the culvert structure to achieve the same design discharge and afflux. It is believed that fish-turbulence interplay may facilitate upstream migration, albeit an optimum design must be based upon a careful characterisation of both hydrodynamics and fish kinematics. [24] [30] [31] Finally the practical engineering design implications cannot be ignored, while a solid understanding of turbulence typology is a basic requirement to any successful boundary treatment conducive of upstream fish passage. [32]
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: CS1 maint: numeric names: authors list (link)A weir or low-head dam is a barrier across the width of a river that alters the flow characteristics of water and usually results in a change in the height of the river level. Weirs are also used to control the flow of water for outlets of lakes, ponds, and reservoirs. There are many weir designs, but commonly water flows freely over the top of the weir crest before cascading down to a lower level. There is no single definition as to what constitutes a weir.
Bonneville Lock and Dam consists of several run-of-the-river dam structures that together complete a span of the Columbia River between the U.S. states of Oregon and Washington at River Mile 146.1. The dam is located 40 miles (64 km) east of Portland, Oregon, in the Columbia River Gorge. The primary functions of Bonneville Lock and Dam are electrical power generation and river navigation. The dam was built and is managed by the United States Army Corps of Engineers. At the time of its construction in the 1930s it was the largest water impoundment project of its type in the nation, able to withstand flooding on an unprecedented scale. Electrical power generated at Bonneville is distributed by the Bonneville Power Administration. Bonneville Dam is named for Army Capt. Benjamin Bonneville, an early explorer credited with charting much of the Oregon Trail. The Bonneville Dam Historic District was designated a National Historic Landmark District in 1987.
The Hiram M. Chittenden Locks, or Ballard Locks, is a complex of locks at the west end of Salmon Bay in Seattle, Washington's Lake Washington Ship Canal, between the neighborhoods of Ballard to the north and Magnolia to the south.
The English River Thames is navigable from Cricklade or Lechlade to the sea, and this part of the river falls 71 meters (234 feet). There are 45 locks on the river, each with one or more adjacent weirs. These lock and weir combinations are used for controlling the flow of water down the river, most notably when there is a risk of flooding, and provide for navigation above the tideway.
Richmond Lock and Footbridge is a lock, rising and falling low-tide barrage integrating controlled sluices and pair of pedestrian bridges on the River Thames in southwest London, England, and is a Grade II* listed structure. It is the furthest downstream of the forty-five Thames locks and the only one owned and operated by the Port of London Authority. It was opened in 1894 and is north-west of the centre of Richmond in a semi-urban part of southwest London. Downstream are Syon Park and Kew Gardens on opposite banks. It connects the promenade at Richmond with the neighbouring district of St. Margarets on the west bank during the day and is closed at night to pedestrians – after 19:30 GMT or after 21:30 when BST is in use. At high tide the sluice gates are raised and partly hidden behind metal arches forming twin footbridges.
A spillway is a structure used to provide the controlled release of water downstream from a dam or levee, typically into the riverbed of the dammed river itself. In the United Kingdom, they may be known as overflow channels. Spillways ensure that water does not damage parts of the structure not designed to convey water.
A culvert is a structure that channels water past an obstacle or to a subterranean waterway. Typically embedded so as to be surrounded by soil, a culvert may be made from a pipe, reinforced concrete or other material. In the United Kingdom, the word can also be used for a longer artificially buried watercourse.
Hells Gate is an abrupt narrowing of British Columbia's Fraser River, located immediately downstream of Boston Bar in the southern Fraser Canyon. The towering rock walls of the Fraser River plunge toward each other forcing the waters through a passage only 35 metres (115 ft) wide. It is also the name of the rural locality at the same location.
A low-water crossing is a low-elevation roadway traversing over a waterbody that stays dry above the water when the flow is low, but is designed to get submerged under high-flow conditions such as floods. This type of crossing is much cheaper to build than a high bridge that keeps the road surface consistently above the highest water level, and is usually deployed in semi-arid areas where high-volume rainfall is rare and the existing channel is shallow, particularly in developing countries.
Molesey Lock is a lock on the River Thames in England at East Molesey, Surrey on the right bank.
San Francisquito Creek is a creek that flows into southwest San Francisco Bay in California, United States. Historically it was called the Arroyo de San Francisco by Juan Bautista de Anza in 1776. San Francisquito Creek courses through the towns of Portola Valley and Woodside, as well as the cities of Menlo Park, Palo Alto, and East Palo Alto. The creek and its Los Trancos Creek tributary define the boundary between San Mateo and Santa Clara counties.
A drop structure, also known as a grade control, sill, or weir, is a manmade structure, typically small and built on minor streams, or as part of a dam's spillway, to pass water to a lower elevation while controlling the energy and velocity of the water as it passes over. Unlike most dams, drop structures are usually not built for water impoundment, diversion, or raising the water level. Mostly built on watercourses with steep gradients, they serve other purposes such as water oxygenation and erosion prevention.
Hubert Chanson is a professional engineer and academic in hydraulic engineering and environmental fluid mechanics. Since 1990 he has worked at the University of Queensland.
Savage Rapids Dam was an approximately 39-foot-high (12 m), 500-foot-long (150 m) irrigation diversion dam spanning the mainstem of the Rogue River in Josephine County, Oregon. The dam was demolished and removed in 2009. From 1921 until the spring of 2009, the Savage Rapids Dam almost entirely functioned for irrigation purposes, and it did not provide any flood control, hydro-electric power, inland waterway, or other significant beneficial uses. It only provided very minor recreational or wildlife benefits.
Red Bluff Diversion Dam is a disused irrigation diversion dam on the Sacramento River in Tehama County, California, United States, southeast of the city of Red Bluff. Until 2013, the dam provided irrigation water for two canals that serve 150,000 acres (61,000 ha) of farmland on the west side of the Sacramento Valley. The dam and canals are part of the Sacramento Canals Unit of the Central Valley Project, operated by the U.S. Bureau of Reclamation. In 2013, the dam was decommissioned and the river allowed to flow freely through the site in order to protect migrating fish. A pumping plant constructed a short distance upstream now supplies water to the canal system.
The Nimbus Fish Hatchery is located in eastern Sacramento County, built on the downstream side of the Nimbus Dam. It is one of the 21 fish hatcheries the California Department of Fish and Wildlife oversees. Chinook salmon and steelhead are raised, and about 4 million Chinook salmon and 430,000 steelheads released each year.
An elver pass or eel pass is a waterway modification constructed to mitigate the effects of obstructions, especially manmade weirs, on waterways, watercourses, ditches, drains, channels and flumes, on the movement of eels, fish and elvers. Powerful swimmers, including salmon and sea trout, find it easy to pass through many structures. However, it is widely accepted that some structures make fish migration more difficult upstream.
Liverpool Weir is a heritage-listed weir on the Georges River at Heathcote Road near Newbridge Road, Liverpool, Sydney, New South Wales, Australia. It was designed by David Lennox and built from 1836 by convict labour, directed by Captain W. H. Christie. It is also known as Bourke's Dam. It was added to the New South Wales State Heritage Register on 13 August 2010.
Craven Dam is at the confluence of the Qu'Appelle River and Last Mountain Creek and immediately east of the village of Craven on the Qu'Appelle River at LSD SW 24-20-21 W2. It is in the Canadian province of Saskatchewan in the RM of Longlaketon No. 219. The dam does not create a reservoir as its purpose is to regulate water flow along the Qu'Appelle River. The dam is operated by the Saskatchewan Water Security Agency and can be accessed on the north side by Highway 99.
Ecohydraulics is an interdisciplinary science studying the hydrodynamic factors that affect the survival and reproduction of aquatic organisms and the activities of aquatic organisms that affect hydraulics and water quality. Considerations include habitat maintenance or development, habitat-flow interactions, and organism responses. Ecohydraulics assesses the magnitude and timing of flows necessary to maintain a river ecosystem and provides tools to characterize the relation between flow discharge, flow field, and the availability of habitat within a river ecosystem. Based on this relation and insights into the hydraulic conditions optimal for different species or communities, ecohydraulics-modeling predicts how hydraulic conditions in a river change, under different development scenarios, the aquatic habitat of species or ecological communities. Similar considerations also apply to coastal, lake, and marine eco-systems.