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83-474: In 1898, plans began to form to build a hydroelectric power generation dam near Coon Rapids, Minnesota. While originally conceived as a private venture, in 1911 Congress approved federal funding for the dam to make it a joint private-public operation. Land was purchased from John Dunn, after whom the island in the middle of the channel is named. H. M. Byllesby & Company began construction the dam in January 1913 and

166-419: A fish ladder are often taken to counteract this. Navigation locks have also potential to be operated as fishways to provide increased access for a range of biota. Locks can be built side by side on the same waterway. This is variously called doubling , pairing , or twinning . The Panama Canal has three sets of double locks. Doubling gives advantages in speed, avoiding hold-ups at busy times and increasing

249-451: A $ 6.2 million two-year plan to reconstruct the dam. While the original footings were used, the rest of the dam was entirely rebuilt. The new dam consisted of four gates with inflatable rubber bladders. Tears in the bladders requiring repair occurred in 1997 and 2000, resulting in a complete replacement of the bladders with an upgraded design in 2002. The rubber bladders installed in the 1997 reconstruction proved to be ineffective in preventing

332-594: A 13-foot difference between the dam and the original riverbed. The pool is around 600 acres, with the effects of the dam diminishing after the Ferry Street bridge in Champlin , about six miles upstream. Three Rivers Park District , a special park district serving the Twin Cities Hennepin , Carver , Dakota , Scott , and Ramsey counties, owns the dam and operates the 160-acre Mississippi Gateway Regional Park on

415-555: A boat in a lock. One incident, which took place in June 1873 on the Chesapeake and Ohio Canal, involved the boat the Henry C. Flagg and its drunk captain. That boat was already leaking; the crew, having partially pumped the water out, entered Lock 74, moving in front of another boat. Because they failed to snub the boat, it crashed into and knocked out the downstream gates. The outrush of water from

498-464: A boat in the lock. A 200-ton boat moving at a few miles an hour could destroy the lock gate. To prevent this, a rope was wound around the snubbing post as the boat entered the lock. Pulling on the rope slowed the boat, due to the friction of the rope against the post. A rope 2 + 1 ⁄ 2 inches (6.4 cm) in diameter and about 60 feet (18 meters) long was typically used on the Erie Canal to snub

581-500: A boat travelling upstream, the process is reversed; the boat enters the empty lock, and then the chamber is filled by opening a valve that allows water to enter the chamber from the upper level. The whole operation will usually take between 10 and 20 minutes, depending on the size of the lock and whether the water in the lock was originally set at the boat's level. Boaters approaching a lock are usually pleased to meet another boat coming towards them, because this boat will have just exited

664-528: A broad canal for more than one boat to be in a staircase at the same time, but managing this without waste of water requires expertise. On English canals, a staircase of more than two chambers is usually staffed: the lockkeepers at Bingley (looking after both the "5-rise" and the "3-rise") ensure that there are no untoward events and that boats are moved through as speedily and efficiently as possible. Such expertise permits miracles of boat balletics: boats travelling in opposite directions can pass each other halfway up

747-426: A flight of locks is simply a series of locks in close-enough proximity to be identified as a single group. For many reasons, a flight of locks is preferable to the same number of locks spread more widely: crews are put ashore and picked up once, rather than multiple times; transition involves a concentrated burst of effort, rather than a continually interrupted journey; a lock keeper may be stationed to help crews through

830-412: A gate, or pair of half-gates, traditionally made of oak or elm but now usually made of steel ). The most common arrangement, usually called miter gates , was invented by Leonardo da Vinci sometime around the late 15th century. On the old Erie Canal , there was a danger of injury when operating the paddles: water, on reaching a certain position, would push the paddles with a force which could tear

913-435: A lock is a fixed chamber in which the water level can be varied; whereas in a caisson lock , a boat lift , or on a canal inclined plane , it is the chamber itself (usually then called a caisson ) that rises and falls. Locks are used to make a river more easily navigable, or to allow a canal to cross land that is not level. Later canals used more and larger locks to allow a more direct route to be taken. A pound lock

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996-421: A lock. To help boats traveling downstream exit a lock, the locksman would sometimes open the paddles to create a swell, which would help "flush" the boat out of the lock. A boatsman might ask for a back swell, that is, to open and shut the paddles a few times to create some waves, to help him get off the bank where he was stuck. If boats ran aground (from being overloaded) they sometimes asked passing crews to tell

1079-537: A main 1,000-foot (300 m) section with a 103-foot (31 m) control gate and nine additional steel gates, connecting the Hennepin County side to Dunn Island on the Anoka County side of the river. A shorter 400 foot section, originally containing the 200 foot long powerhouse, connects the island to the Anoka County side. The difference between the headwater and tailwater is usually around 19 feet (5.8 m), with

1162-500: A proposed amendment to the Minnesota constitution that would have banned same-sex marriage . U.S. House MN Senate The Majority of Scott County is in the 55th Senate District. Small portions of the county are in the 20th and 56th Districts. MN House The Majority of the County take place within the 55A & 55B Districts. Shakopee is in the 55A district and most of the rest of

1245-533: A separate category. Hispanics/Latinos can be of any race. As of the census of 2000, the county had 89,498 people, 30,692 households, and 23,970 families. The population density was 251 inhabitants per square mile (97/km ). There were 31,609 housing units at an average density of 89 per square mile (34/km ). The county's racial makeup was 93.65% White , 0.92% Black or African American , 0.77% Native American , 2.17% Asian , 0.03% Pacific Islander , 1.24% from other races , and 1.21% from two or more races. 2.66% of

1328-430: A short way into the chamber from below the upper gates. Allowing the rear of the boat to "hang" on the cill is the main danger when descending a lock, and the position of the forward edge of the cill is usually marked on the lock side by a white line. The edge of the cill is usually curved, protruding less in the center than at the edges. In some locks, there is a piece of oak about 9 in (23 cm) thick which protects

1411-480: A staircase lock can be used as an emergency dry dock). To avoid these mishaps, it is usual to have the whole staircase empty before starting to descend, or full before starting to ascend, apart from the initial chamber. One striking difference in using a staircase of either type (compared with a single lock, or a flight) is the best sequence for letting boats through. In a single lock (or a flight with room for boats to pass) boats should ideally alternate in direction. In

1494-404: A staircase, however, it is quicker for a boat to follow a previous one going in the same direction. Partly for this reason staircase locks such as Grindley Brook, Foxton, Watford and Bratch are supervised by lockkeepers, at least during the main cruising season, they normally try to alternate as many boats up, followed by down as there are chambers in the flight. As with a flight, it is possible on

1577-454: A swell to anyone to help them on the way, but some would ask for money for the swell. The Erie Canal management did not like swelling for two reasons. First, it used too much water lowering the water on the pound above sometimes causing boats to run aground. In addition, it raised the water level on the pound below, causing some boats to strike bridges or get stuck. On horse-drawn and mule-drawn canals, snubbing posts were used to slow or stop

1660-426: Is a normal top gate, and the intermediate gates are all as tall as the bottom gate). As there is no intermediate pound, a chamber can only be filled by emptying the one above, or emptied by filling the one below: thus the whole staircase has to be full of water (except for the bottom chamber) before a boat starts to ascend, or empty (except for the top chamber) before a boat starts to descend. In an "apparent" staircase

1743-480: Is changing dramatically. Cities are continually growing, causing an increase in population from roughly 90,000 in 2000 to more than 150,000 today, making Scott County one of Minnesota's fastest-growing counties. According to the United States Census Bureau , the county has an area of 368 square miles (950 km ), of which 356 square miles (920 km ) is land and 12 square miles (31 km ) (3.2%)

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1826-479: Is entirely within the county and within the cities of Prior Lake and Shakopee. Due to its proximity to major cities, the tribe has earned revenues at its gaming casinos and hotel; it has used funds to reinvest in economic development for the tribe, founding numerous other enterprises. The tribe is also committed to philanthropy, having donated more than $ 350 million to organizations and causes in Scott County and across

1909-626: Is most commonly used on canals and rivers today. A pound lock has a chamber with gates at both ends that control the level of water in the pound. In contrast, an earlier design with a single gate was known as a flash lock . Pound locks were first used in China during the Song dynasty (960–1279 CE), having been pioneered by the Song politician and naval engineer Qiao Weiyue in 984. They replaced earlier double slipways that had caused trouble and are mentioned by

1992-443: Is only a staircase if successive lock chambers share a gate (i.e. do not have separate top and bottom gates with a pound between them). Most flights are not staircases, because each chamber is a separate lock (with its own upper and lower gates), there is a navigable pound (however short) between each pair of locks, and the locks are operated in the conventional way. However, some flights include (or consist entirely of) staircases. On

2075-533: Is part of the Minneapolis - St. Paul - Bloomington , MN- WI Metropolitan Statistical Area . It is a member of the Metropolitan Council , and shares many of the council's concerns about responsible growth management, advocating for progressive development concepts such as clustering, open-space design, and the preservation of open space and rural/agricultural land. The Shakopee-Mdewakanton Indian Reservation

2158-598: Is stocked with Rainbow Trout; other species are present as well. Cenaiko Lake was created in 1987 and is named after former Anoka County commissioner Nick Cenaiko. Over 350,000 people visit the parks each year. The dam connects to Elm Creek Park Reserve via the Rush Creek Regional Trail . Lock (water navigation) A lock is a device used for raising and lowering boats , ships and other watercraft between stretches of water of different levels on river and canal waterways . The distinguishing feature of

2241-420: Is water. It is the third-smallest county in Minnesota by land area and second-smallest by total area. The Minnesota River is the county's boundary in both the north and the west. The broad river valley juts through glacial sediment into some of the oldest rock known. Now mostly farmland, it was an oak savanna and a mixture of grass and clusters of trees that grew parallel to the river valley. The savanna bordered

2324-846: The Bollène lock on the River Rhône has a fall of at least 23 m (75 ft), the Leerstetten, Eckersmühlen and Hilpoltstein locks on the Rhine–Main–Danube Canal have a fall of 24.67 m (80.9 ft), each and the Oskemen Lock on the Irtysh River in Kazakhstan has a drop of 42 m (138 ft). The natural extension of the flash lock , or staunch, was to provide an upper gate (or pair of gates) to form an intermediate "pound" which

2407-464: The Caledonian Canal the lock gates were operated by man-powered capstans , one connected by chains to open the gate and another to draw it closed. By 1968 these had been replaced by hydraulic power acting through steel rams. The construction of locks (or weirs and dams) on rivers obstructs the passage of fish. Some fish such as lampreys, trout and salmon go upstream to spawn. Measures such as

2490-470: The Grand Union . Operation of a staircase is more involved than a flight. Inexperienced boaters may find operating staircase locks difficult. The key worries (apart from simply being paralysed with indecision) are either sending down more water than the lower chambers can cope with (flooding the towpath, or sending a wave along the canal) or completely emptying an intermediate chamber (although this shows that

2573-552: The Kennet and Avon Canal . Scott County, Minnesota Scott County is a county in the U.S. state of Minnesota . As of the 2020 census , the population was 150,928. Its county seat is Shakopee . Shakopee is also the largest city in Scott County, the twenty-first-largest city in Minnesota, and the sixteenth-largest Twin Cities suburb. The county was organized in 1853 and named in honor of General Winfield Scott . Scott County

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2656-700: The Rochdale Canal , which both have a rise of nearly 20 feet (6.1 m). Both locks are amalgamations of two separate locks, which were combined when the canals were restored to accommodate changes in road crossings. By comparison, the Carrapatelo and Valeira locks on the Douro river in Portugal, which are 279 feet (85 m) long and 39 feet (12 m) wide, have maximum lifts of 115 and 108 feet (35 and 33 m) respectively. The two Ardnacrusha locks near Limerick on

2739-581: The Song dynasty (960–1279 CE). The Songshi or History of the Song Dynasty, volume 307, biography 66, records how Qiao Weiyue, a high-ranking tax administrator, was frustrated at the frequent losses incurred when his grain barges were wrecked on the West River near Huai'an in Jiangsu . The soldiers at one double slipway, he discovered, had plotted with bandits to wreck heavy imperial barges so that they could steal

2822-535: The " Big Woods ", a "closed-forest savanna" that covered most of Minnesota before it was logged in the mid-19th century. Scott is one of 17 Minnesota savanna counties with more savanna soils than either forest or prairie soils. One example of native vegetation in Scott County: Note: the US Census treats Hispanic/Latino as an ethnic category. This table excludes Latinos from the racial categories and assigns them to

2905-588: The 19th century. With the fast-growing farms, towns sprang up. Shakopee , the County Seat, began in 1851 as a trading post by the Dakota Village of Chief Shakopee (or Shakpay). Other towns were established alongside transportation routes. When the railroads came to Minnesota, they became the primary mode of transportation, and eventually highways were developed along the ox cart trails between the communities. Due to urban sprawl and suburbanization this rural county

2988-485: The Anoka County side of the dam. Due to the cost of upkeep, Three Rivers Park District considered selling the dam to the Minnesota Department for Natural Resources in 2010, resulting in a dispute with Anoka County in 2011 which caused Three Rivers Park district to revoke the lease. Ultimately, Anoka County purchased the leased land from the park district. By the 1990s, the dam was facing serious wear and tear, and

3071-510: The Chinese polymath Shen Kuo (1031–1095) in his book Dream Pool Essays (published in 1088), and fully described in the Chinese historical text Song Shi (compiled in 1345): The distance between the two locks was rather more than 50 paces, and the whole space was covered with a great roof like a shed. The gates were 'hanging gates'; when they were closed the water accumulated like a tide until

3154-715: The Dakota Indians to reservations in upper Minnesota. Scott County was established and organized by an Act passed in the legislature on March 5, 1853. The 369-square-mile (960 km ) county was named after General Winfield Scott . Settlers started entering the area in the mid-1850s. The Minnesota River and the ox cart trails were the primary transportation routes. The first settlers were Yankees, followed by groups of Germans , Irish , Czechs , and Scandinavians . They each brought their own traditions and religions. Most of these settlers became farmers. Fur trading, lumbering, and farming were Minnesota's major industries all throughout

3237-568: The Democratic ranks. However, since the “Reagan Revolution”, Scott County has become solidly Republican voting, with no Democrat gaining a majority of the county's vote since Jimmy Carter in 1976, although Carter in 1980 and Bill Clinton in 1992 and 1996 won pluralities. Although a conservative stronghold in modern times, the suburban voters of Scott County, like those elsewhere, tend to be more liberal on social issues. For example, while Mitt Romney handily won Scott County in 2012, voters also rejected

3320-552: The Grand Union (Leicester) Canal, the Watford flight consists of a four-chamber staircase and three separate locks; and the Foxton flight consists entirely of two adjacent 5-chamber staircases. Where a very steep gradient has to be climbed, a lock staircase is used. There are two types of staircase, "real" and "apparent". A "real" staircase can be thought of as a "compressed" flight, where

3403-719: The Minnesota River. They had many trails leading to these settlements and to the Red River Valley in the North, and the Prairie du Chien to the Southeast. These trails were later used by the fur traders and settlers, and were known as the "ox cart trails." The area of Scott County, as well as much of southern Minnesota, was opened for settlement by two treaties signed at Mendota and Traverse des Sioux , in 1851 and 1853. These treaties removed

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3486-748: The Shakopee-Mdewakanton Dakota; the Renaissance Festival , and Valleyfair Amusement Park. Scott County was first inhabited by two bands of the Santee Sioux (Dakota) Indians, the Mdewakanton and Wahpeton . Their semi-nomadic life followed a seasonal cycle. They gathered food, hunted, fished, and planted corn. In the summer the Dakota villages were occupied but in the winter the groups separated for hunting. They had many permanent villages along

3569-512: The Shannon navigation in Ireland have a rise of 100 feet (30 m). The upper chamber rises 60 feet (18 m) and is connected to the lower chamber by a tunnel, which when descending does not become visible until the chamber is nearly empty. A pound is the level stretch of water between two locks (also known as a reach ). The cill , also spelled sill , is a narrow horizontal ledge protruding

3652-631: The St. Anthony Falls Commercial Club lobbied for Congress to add a lock to the dam. However, as the river above the dam was deemed not to be navigable, the power company was not required to build the $ 150,000 lock. The lack of a lock makes it the theoretical northernmost navigable point on the Mississippi River; however, since 2015, Upper St. Anthony Falls lock have been sealed to prevent the spread of Asian carp and as such Saint Anthony Falls in Minneapolis are

3735-470: The advent of canals in Britain. The sides of the turf-lock are sloping so, when full, the lock is quite wide. Consequently, this type of lock needs more water to operate than vertical-sided brick- or stone-walled locks. On British canals and waterways most turf-sided locks have been subsequently rebuilt in brick or stone, and so only a few good examples survive, such as at Garston Lock , and Monkey Marsh Lock , on

3818-463: The bottom cill at all but the higher tides – the new bottom chamber rises just far enough to get the boat over the original lock cill. In China, the recently completed Three Gorges Dam includes a double five-step staircase for large ships, and a ship lift for vessels of less than 3000 metric tons. Examples of "apparent" staircases are Foxton Locks and Watford Locks on the Leicester Branch of

3901-617: The canal would cause frequent interruptions of the heavy road traffic. It can be emptied by pumping – but as this uses a lot of electricity the method used when water supplies are adequate is to drain the lock to a nearby burn . In 2016 the Kieldrecht Lock in the Port of Antwerp in Belgium took over the title of the world's largest lock from the Berendrecht Lock in the same port and still has

3984-588: The chambers so that some water from the emptying chamber helps to fill the other. This facility has long been withdrawn on the English canals, although the disused paddle gear can sometimes be seen, as at Hillmorton on the Oxford Canal . Elsewhere they are still in use; a pair of twinned locks was opened in 2014 on the Dortmund–Ems Canal near Münster , Germany. The once-famous staircase at Lockport, New York ,

4067-617: The chambers still have common gates, but the water does not pass directly from one chamber to the next, going instead via side ponds. This means it is not necessary to ensure that the flight is full or empty before starting. Examples of famous "real" staircases in England are Bingley and Grindley Brook . Two-rise staircases are more common: Snakeholme Lock and Struncheon Hill Lock on the Driffield Navigation were converted to staircase locks after low water levels hindered navigation over

4150-404: The chance of a boat finding a lock set in its favour. There can also be water savings: the locks may be of different sizes, so that a small boat does not need to empty a large lock; or each lock may be able to act as a side pond (water-saving basin) for the other. In this latter case, the word used is usually "twinned": here indicating the possibility of saving water by synchronising the operation of

4233-514: The concept has been suggested in a number of cases, the only example in the world of a drop lock that has actually been constructed is at Dalmuir on the Forth and Clyde Canal in Scotland. This lock, of the single-chamber type, was incorporated during the restoration of the canal, to allow the replacement of a swing bridge (on a busy A road) by a fixed bridge, and so answer criticisms that the restoration of

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4316-463: The country. The Minnesota River had supported the county's fur trading, lumbering, and farming industries in the 19th century. Today, Scott County experiences a growing mix of commercial, industrial, and housing development, but is still primarily rural. Scott County is home to several historical, scenic, and entertainment destinations including Canterbury Park , The Landing, Minnesota's Largest Candy Store , Elko Speedway , Mystic Lake Casino run by

4399-449: The county to shift overwhelmingly to Warren G. Harding in 1920 before swinging to Robert La Follette , coreligionist Al Smith and fellow “wet” Democrat Franklin D. Roosevelt . In 1936 the county's isolationism gave a powerful vote to William Lemke ’s Union Party , and apart from Harry Truman ’s Farm Belt appeal in the 1948 election Scott County would turn Republican until another Catholic nominee, John F. Kennedy , returned it to

4482-535: The current practical limit. By the 1960s, hydroelectric generation on the dam was no longer profitable, and power generation was halted in 1966. The plant was demolished in 1967, and in 1969 Northern States Power Company donated the dam to the Hennepin County Parks District . A walkway was constructed across the dam in 1977, and the park opened in 1978. In 1994, Anoka County entered a thirty-year lease agreement with Three Rivers Park District for

4565-448: The first to solve the problem of keeping the Nile free of salt water when his engineers invented the lock around 274/273 BC. All pound locks have three elements: The principle of operating a lock is simple. For instance, if a boat travelling downstream finds the lock already full of water: If the lock were empty, the boat would have had to wait 5 to 10 minutes while the lock was filled. For

4648-599: The first true pound lock was built in 1396 at Damme near Bruges , Belgium. The Italian Bertola da Novate (c. 1410–1475) constructed 18 pound locks on the Naviglio di Bereguardo (part of the Milan canal system sponsored by Francesco Sforza ) between 1452 and 1458. In Ancient Egypt, the river-locks was probably part of the Canal of the Pharaohs : Ptolemy II is credited by some for being

4731-425: The flight quickly; and where water is in short supply, a single pump can recycle water to the top of the whole flight. The need for a flight may be determined purely by the lie of the land, but it is possible to group locks purposely into flights by using cuttings or embankments to "postpone" the height change. Examples: Caen Hill locks, Devizes . "Flight" is not synonymous with "Staircase" (see below). A set of locks

4814-512: The form of the now-disused Écluse des Lorraines , connecting the Canal latéral à la Loire with the River Allier . A drop lock can consist of two conventional lock chambers leading to a sump pound, or a single long chamber incorporating the sump – although the term properly applies only to the second case. As the pounds at either end of the structure are at the same height, the lock can only be emptied either by allowing water to run to waste from

4897-516: The inside walls of the lock with wood, so as not to abrade the boats. This was done, for instance, on the Chesapeake and Ohio Canal with the locks near the Paw Paw Tunnel . and also the Chenango Canal On large modern canals, especially very large ones such as ship canals , the gates and paddles are too large to be hand operated, and are operated by hydraulic or electrical equipment. On

4980-414: The intermediate pounds have disappeared, and the upper gate of one lock is also the lower gate of the one above it. However, it is incorrect to use the terms staircase and flight interchangeably: because of the absence of intermediate pounds, operating a staircase is very different from operating a flight. It can be more useful to think of a staircase as a single lock with intermediate levels (the top gate

5063-450: The lock caused the upstream gates to slam shut, breaking them also, and sending a cascade of water over the boat, sinking it. This suspended navigation on the canal for 48 hours until the lock gates could be replaced and the boat removed from the lock. To economise, especially where good stone would be prohibitively expensive or difficult to obtain, composite locks were made, i.e. they were constructed using rubble or inferior stone, dressing

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5146-413: The lock on their level and therefore set the lock in their favour – saving about 5 to 10 minutes. However, this is not true for staircase locks, where it is quicker for boats to go through in convoy, and it also uses less water. The rise is the change in water-level in the lock. The two deepest locks on the English canal system are Bath deep lock on the Kennet and Avon Canal and Tuel Lane Lock on

5229-656: The new canal was low. This resulted in a sequential pair of locks, with gates pointing in opposite directions: one example was at Hall Green near Kidsgrove , where the southern terminus of the Macclesfield Canal joined the Hall Green Branch of the earlier Trent and Mersey Canal . The four gate stop lock near Kings Norton Junction, between the Stratford-upon-Avon Canal and the Worcester and Birmingham Canal

5312-465: The population were Hispanic or Latino of any race. 39.6% were of German , 12.6% Norwegian , 8.3% Irish and 5.1% Swedish ancestry. There were 30,692 households, of which 45.40% had children under the age of 18 living with them, 66.90% were married couples living together, 7.40% had a female householder with no husband present, and 21.90% were non-families. 16.00% of all households were made up of individuals, and 4.50% had someone living alone who

5395-461: The required level was reached, and then when the time came it was allowed to flow out. The water level could differ by 4 or 5 feet (1.2 or 1.5 m) at each lock and in the Grand Canal the level was raised in this way by 138 feet (42 m). In medieval Europe a sort of pound lock was built in 1373 at Vreeswijk , Netherlands. This pound lock serviced many ships at once in a large basin . Yet

5478-624: The solid part of the lock cill. On the Oxford Canal it is called a babbie; on the Grand Union Canal it is referred to as the cill bumper. Some canal operation authorities, primarily in the United States and Canada, call the ledge a miter sill (mitre sill in Canada). Gates are the watertight doors which seal off the chamber from the upper and lower pounds. Each end of the chamber is equipped with

5561-480: The southwest side of the dam. Anoka County Parks owns and operates a 446-acre park, Coon Rapids Dam Regional Park , on the northeast of the dam. Many species, including mink, beaver, hawks, osprey, deer, turtles and river otters, can be spotted in the parks. Both parks are sites for the National Parks Passport Program . Cenaiko Lake, a 28 1 ⁄ 2 acre artificial lake on the Anoka County side,

5644-407: The spilled grain. In 984 Qiao installed a pair of sluice-gates two hundred and fifty feet apart, the entire structure roofed over like a building. By siting two staunch gates so close to one another, Qiao had created a short stretch of canal, effectively a pound-lock, filled from the canal above by raising individual wooden baulks in the top gate and emptied into the canal below by lowering baulks in

5727-509: The spread of Asian carp further up the river. Between 2013 and 2014, the rubber bladders were replaced by nine steel gates in a $ 16 million project. As part of the same renovation, a 450-foot stilling basin was installed, replacing a deteriorating concrete apron. There have been proposals to restore power generation at the dam. Proposals by the park district from 2009 proposed a $ 30 million plant which would generate 44 megawatts per year. The proposals have not gained traction. The dam consists of

5810-411: The staircase by moving sideways around each other; or at peak times, one can have all the chambers full simultaneously with boats travelling in the same direction. When variable conditions meant that a higher water level in the new canal could not be guaranteed, then the older company would also build a stop lock (under its own control, with gates pointing towards its own canal) which could be closed when

5893-453: The steepest drop in median income of all the populous counties in Minnesota and household wealth fell by 10 percent. In its early history Scott County was heavily Democratic due to being largely German Catholic and opposed to the pietistic Scandinavian Lutheran Republican Party of that era . It would never vote Republican until Theodore Roosevelt swept every Minnesota county in 1904 but anti- Woodrow Wilson feeling from World War I caused

5976-413: The sump to a lower stream or drain, or (less wastefully) by pumping water back up to the canal. Particularly in the two-chamber type, there would be a need for a bypass culvert, to allow water to move along the interrupted pound and so supply locks further down the canal. In the case of the single-chamber type, this can be achieved by keeping the lock full and leaving the gates open while not in use. While

6059-488: The title for largest volume. In 2022 the IJmuiden sea lock serving the Port of Amsterdam became the world's largest lock by surface area. The lock is 500 m (1,600 ft) long, 70 m (230 ft) wide and has sliding lock gates creating a usable depth of 18 m (59 ft). The size of locks cannot be compared without considering the difference in water level that they are designed to operate under. For example,

6142-400: The top gate and raising ones in the lower. A turf-sided lock is an early form of canal lock design that uses earth banks to form the lock chamber, subsequently attracting grasses and other vegetation, instead of the now more familiar and widespread brick, stone, or concrete lock wall constructions. This early lock design was most often used on river navigations in the early 18th century before

6225-404: The upstream lock to give them an extra heavy swell, which consisted of opening all the paddles on the lock gate, creating a surge that affected the whole pound below. On the Erie Canal, some loaded boats needed a swell to get out of the lock. Particularly lumber boats, being top heavy, would list to one side and get stuck in the lock, and needed a swell to get them out. Some lockkeepers would give

6308-405: The windlass (or handle) out of one's hands, or if one was standing in the wrong place, could knock one into the canal, leading to injuries and drownings. On the Chesapeake and Ohio Canal, the lockkeepers were required to remove the windlasses from all lock paddles at night, to prevent unauthorized use. A swell was caused by opening suddenly the paddle valves in the lock gates, or when emptying

6391-440: Was $ 66,612, and the median family income was $ 72,212 (these figures had risen to $ 80,968 and $ 90,489 respectively as of a 2007 estimate). Males had a median income of $ 46,593 versus $ 32,482 for females. The county's per capita income was $ 26,418. About 2.00% of families and 3.40% of the population were below the poverty line , including 3.40% of those under age 18 and 7.50% of those age 65 or over. However, in 2011, Scott County saw

6474-456: Was 65 years of age or older. The average household size was 2.89 and the average family size was 3.25. 31.20% of the county's population was under age 18, 6.70% was from age 18 to 24, 37.30% was from age 25 to 44, 18.60% was from age 45 to 64, and 6.20% was age 65 or older. The median age was 33 years. For every 100 females there were 101.90 males. For every 100 females age 18 and over, there were 100.00 males. The county's median household income

6557-456: Was all that need be emptied when a boat passed through. This type of lock, called a pound lock was known in Imperial China and ancient Europe and was used by Greek engineers in the Canal of the Pharaohs under Ptolemy II (284 to 246 BC), when engineers solved the problem of overcoming the difference in height through canal locks . Pound locks were first used in medieval China during

6640-416: Was also a doubled set of locks. Five twinned locks allowed east- and west-bound boats to climb or descend the 60 feet (18 m) Niagara Escarpment , a considerable engineering feat in the nineteenth century. While Lockport today has two large steel locks, half of the old twin stair acts as an emergency spillway and can still be seen, with the original lock gates having been restored in early 2016. Loosely,

6723-506: Was completed in March 1914; power generation began in August 1914. Over 42,000 cubic yards of concrete were used in the construction of the dam. It had 28 steel gates which were raised and lowered to allow water to flow under them. One of the original steel gates is available for viewing on the Anoka County side of the dam. The dam does not contain a lock . In November 1913, after construction started,

6806-522: Was rated a "significant hazard" by the Army Corps of Engineers with severe effects predicted if the dam collapsed, including possible deaths. Repairs were recommended within five years. The original concrete pilings were wearing away, foundation soil was eroding, and many of the twenty-eight wooden and metal gates were broken and twisted as a result of ice. From 1995 to 1997, Hennepin County Parks carried out

6889-588: Was replaced in 1914 by a pair of guillotine lock gates which stopped the water flow regardless of which canal was higher. These gates have been permanently open since nationalisation. The best known example of a round lock is the Agde Round Lock on the Canal du Midi in France. This serves as a lock on the main line of the canal and allows access to the Hérault River . A second French round lock can be found in

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