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94-479: 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

188-419: 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

282-451: 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

376-614: 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

470-569: 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

564-470: 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

658-500: 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

752-528: 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

846-426: 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

940-412: 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

1034-435: 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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1128-421: 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

1222-550: 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

1316-430: 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

1410-480: 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

1504-404: 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

1598-454: 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

1692-521: A total area of 587 square miles (1,520 km ), of which 562 square miles (1,460 km ) is land and 25 square miles (65 km ) (4.2%) is water. The northern and eastern boundaries of Dakota County are marked by the Minnesota and Mississippi Rivers. Management and jurisdiction of the rivers falls into multiple local, State and Federal agencies. Most of the Minnesota River bank is under

1786-426: 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

1880-623: Is bordered by the Minnesota and Mississippi Rivers on the north, and the state of Wisconsin on the east. The county was the site of historical events at Mendota that defined the state's future, including providing materials for the construction of Fort Snelling across the river and the signing of the Treaty of Traverse des Sioux which ceded land from the native Dakota nation for the Minnesota Territory. The county's history

1974-431: Is home to sites significant in the state's early history. At Mendota, the Treaty of Mendota was signed, opening Southern Minnesota to settlement, and prominent Saint Paul businessmen built their mansions there. Though linked with the state's capital for much of history via rail, Dakota County owes much of its current growth to the expansion of Minneapolis' population which accelerated during the post-World War II boom era of

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2068-638: 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

2162-523: Is now Picnic Island on the south bank of the Minnesota River , Colonel Henry Leavenworth built a stockade fort called "St. Peter's Cantonment" or "New Hope," where materials were assembled for the construction of Fort Snelling to be built on the bluff on the north bank. Permanent settlement on the island was impossible due to annual flooding. Alexis Bailey built some log buildings nearby to trade in furs in 1826. Henry Hastings Sibley later built

2256-443: 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

2350-589: Is served by an elected board of the Soil and Water Conservation District . Dakota County voters tend to vote Democratic. Since 1960, the county has selected the Democratic Party candidate in 71% of national elections (as of 2020). The county terrain consists of low rolling hills, sloping to the river valleys. Its highest point is at Buck Hill in Burnsville, at 1,168 feet above sea level. The county has

2444-609: 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

2538-881: 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

2632-472: 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

2726-476: 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

2820-548: The Kennet and Avon Canal . Dakota County, Minnesota Dakota County is the third-most populous county in the U.S. state of Minnesota , located in the east central portion of the state. As of the 2020 census , the population was 439,882. The population of Dakota County was estimated to be 447,440 in 2023. The county seat is Hastings . Dakota County is named for the Dakota Sioux tribal bands who inhabited

2914-769: The Minnesota Valley National Wildlife Refuge with fish, wildlife, and parkland managed collectively by the United States Fish and Wildlife Service and the Minnesota Department of Natural Resources. The Dakota County Soil and Water Conservation District assists the county's six watershed management organizations (WMO) which include the Black Dog WMO, Gun Club Lake WMO, Lower Minnesota River Watershed District, Lower Mississippi WMO, North Cannon River WMO, and

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3008-722: 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

3102-598: 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

3196-622: The Treaty of St. Peters , the Treaty of Traverse des Sioux , and the Treaty of Mendota in 1851. After the Minnesota Territory was established in 1849, Dakotah County (later Dakota County) spanned from the Mississippi River to the Missouri River . By the time Minnesota achieved statehood in 1858, power and influence had shifted from Mendota, across the rivers to Saint Paul and Minneapolis . By 1900,

3290-455: The stockyards and meat-packing plants in South St. Paul, Minnesota became the world's largest stockyards. Ranchers in the west shipped their livestock to St. Louis , Memphis , and New Orleans . These plants were worked by immigrants from Romania , Serbia , and other Eastern European countries. The rest of the county remained agricultural during the boom of milling activity north of

3384-716: The 1960s. This demand for housing along with two major interstate highways linking Minneapolis (I-35W) and St. Paul (I-35E) to the county, concentrated major growth and demand along the northern end. Today, the cities of Burnsville, Eagan, Apple Valley, Lakeville, Rosemount, Hastings, Inver Grove Heights, Mendota Heights, West St. Paul, and South St. Paul are synonymous with the Twin Cities, as being part of "the Cities." Both Burnsville and Eagan are nearly developed and have become more like independent cities attracting major development than mere residential bedroom suburbs. In contrast,

3478-422: 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

3572-520: 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

3666-567: 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

3760-595: The Mdewakanton Dakota were contacted by French explorer Daniel Greysolon, Sieur du Lhut , and the Mendota ( mdo-TE ) band of the Mdewakanton south of the Minnesota River were contacted by Joseph Nicollet in the 18th century. While Taoyateduta (a.k.a. Little Crow) led the Mendota in northern Dakota County, upstream to the southwest, Chief Black Dog established his village of 600 people around 1750 at

3854-630: The Minnesota River due to lack of bridge connections. Rail access came in 1866 via the Chicago, St. Paul, Minneapolis, and Omaha Railroad which shipped grain to millers. The Minneapolis St. Paul Rochester and Dubuque Electric Traction Company line in 1905 (now the Dan Patch Corridor ), was primary for passengers going to resorts in Burnsville and Lakeville. By the 1950s, population growth shifted to western Dakota County, which had been predominantly Irish and Scottish extending southward toward

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3948-522: The Scandinavians of Southern Minnesota. As population pressures expanded south from Minneapolis and Bloomington, the completion of Interstate 35W and 35E brought about major construction in the post-World War II period, turning villages into cities within 20 years. Burnsville , Apple Valley , Eagan , and Lakeville brought over 200,000 people into the county by the end of the century. The Western and Northern Service Centers were constructed in

4042-522: 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

4136-648: 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

4230-704: The Vermillion River Watershed Joint Powers Organization. Eagan Eureka Township Hastings Lakeville Lilydale Randolph Township Ravenna Township Rosemount West Saint Paul South St. Paul Apple Valley The following protected areas are within or partially within Dakota County: The following parks are located within Dakota County: Since the county grew as a bedroom community of Minneapolis and Saint Paul, over half of

4324-475: 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

4418-710: The area. The name is recorded as "Dahkotah" in the United States Census records until 1851. Dakota County is included in the Minneapolis – St. Paul – Bloomington , MN– WI Metropolitan Statistical Area , the sixteenth largest metropolitan area in the United States with about 3.71 million residents. The largest city in Dakota County is the city of Lakeville , the ninth-largest city in Minnesota and fifth-largest Twin Cities suburb. The county

4512-471: 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

4606-641: 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

4700-599: 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 ,

4794-631: 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

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4888-404: 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

4982-523: 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

5076-522: The county but like many metro counties, Dakota County continues to absorb industry and jobs from the core cities. In the 1600s, Mdewakanton Dakota fled their ancestral home of Mille Lacs Lake in northern Minnesota in response to westward expansion of the Ojibwe nation. According to Dakota tradition, their ancestors pushed out the Iowa who were found settled at the mouth of the Minnesota River. In 1680,

5170-547: 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

5264-549: The early 1990s each with an additional courthouse location. License centers were subsequently set up in Burnsville and Lakeville. Though pressure remained since the postwar boom to move the county seat to a larger community, the Dakota County Board maintained the seat in Hastings, while providing government services across the county. The Registered Historic Places in the county include the settlement at Mendota,

5358-534: The first stone house in Minnesota in 1836, overlooking Fort Snelling. Sibley was a partner in the American Fur Company , and considerable fur trade occurred at Mendota due to the accessibility of the confluence. Ongoing United States expansion into the then "Northwest Territory" led to government purchase of land from the Dakota people (the Mdewakanton, Wahpekute, Wahpeton , and Sisseton bands) via

5452-452: 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

5546-617: 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

5640-425: 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

5734-518: 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

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5828-447: The growing influence of the state's capital, Saint Paul. On the south border, the City of Northfield, technically in Rice County, has expanded north into Dakota however the city itself is allowed into the municipal sewer boundary. Though all of Dakota County is considered part of the metropolitan area and open to major development, the county government has steadily preserved farmland and continues to acquire new permanent natural lands in

5922-481: The homes of well-heeled residents of Hastings, the ethnic gathering places in South Saint Paul, and other sites related to life on the prairie. Dakota County is governed by the Board of Commissioners. The members of the Board as of May 7, 2023, are: Dakota County has an elected Sheriff (Joe Leko) and an elected County Attorney (Kathryn M. Keena). There are appointed boards for the library system, community development agency, and several advisory boards. Dakota County

6016-419: The hub of activity in the county was in Hastings , the county seat, and a focal point of transportation, communication, and commerce. St. Peter's, now Mendota, had lost out to Fort Snelling. Hastings is located on the Mississippi River at the confluence of the St. Croix River and on the Vermillion River , which provided ample water power. Lumber, milling, and railroads provided good incomes. During this time,

6110-401: 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

6204-414: 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

6298-407: The isthmus between Black Dog Lake (which is named after him) and the Minnesota River, near the present site of the Black Dog Power Plant. Following the published expeditions of explorers, in 1805, Zebulon Pike negotiated for military territory with the Mendota band which included land in Dakota County at the Mississippi River confluences with the Minnesota and St. Croix Rivers. In 1819, on what

6392-450: 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

6486-413: 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

6580-419: 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

6674-597: The population were 16 years and over, 73.6% were 18 years and over, 70.5% were 21 years and over, 12.8% were 62 years and over, and 10.0% were 65 years and over. The median age was 36.8 years. The median age for males was 35.7; the median age for females was 37.9. In terms of race and ethnicity, the county was 85.2% White (82.3% Non-Hispanic White), 4.7% Black or African American, 0.4% American Indian and Alaska Native, 4.4% Asian, 0.1% Native Hawaiian and Other Pacific Islander, 2.4% from some other race, and 2.9% from two or more races. Hispanics and Latinos of any race made up 6.0% of

6768-406: The population. In terms of households, 69.5% were family households and 30.5% were non-family households. Approximately 55.2% were husband-wife family households; 26% had children under 18 years of age. Approximately 36.6% of households had children under 18 years of age living in them; 18.6% had people over the age of 65 living in them. The average household size was 2.60 and the average family size

6862-467: 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

6956-473: The residents (54%) work outside the county. Note: the US Census treats Hispanic/Latino as an ethnic category. This table excludes Latinos from the racial categories and assigns them to a separate category. Hispanics/Latinos can be of any race. As of the census of 2010, Dakota County had a population of 398,552, of which 195,661 (49.1%) were male and 202,891 (50.9%) were female. In terms of age, 76.7% of

7050-586: 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

7144-427: The southern part of Dakota County reflects the rural past with small towns such as Farmington, Coates, Vermillion, Hampton, Randolph, and Miesville where street grids and housing dating from the early 20th century can be found. Much of the county is self-contained except for two examples. The City of Hastings, the county seat, lies on both banks of the Mississippi River and was linked historically and physically by rail to

7238-544: The southern townships. This has further defined the boundaries between urbanized and rural which is starkly visible in the outskirts of the developed cities. While the center of population still lies north with more cosmopolitan residents, culturally Dakota County is a rural community and the Dakota County Fair is still a largely agricultural event, held annually in Farmington. Most of northern Dakota County

7332-493: 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,

7426-407: 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

7520-509: 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

7614-411: 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

7708-413: 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

7802-493: 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,

7896-400: 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

7990-404: 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

8084-405: 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

8178-530: Was 3.12. In terms of housing occupancy, 95.3% of households were occupied and 4.7% were vacant. Of the vacant housing units, 2.0% were for rent, 0.1% were rented but not occupied, 1.2% were for sale only, 0.2% were sold but not occupied, 0.5% were for seasonal, recreational, or occasional use, and 0.8% were all other vacants. The homeowner vacancy rate was 1.7% and the rental vacancy rate was 8.1%. Of all occupied housing units, 76.5% were owner-occupied and 23.5% were renter-occupied. The population in owner-occupied units

8272-706: Was 314,833; the average household size was 2.71. The population in renter-occupied units was 80,866; the average household size was 2.26. Dakota County is home to the state's largest school districts and some of the highest paid Superintendents. Nationally recognized Independent School District 196 (Rosemount–Apple Valley–Eagan) houses 28,000 and is the fourth largest school district in the state. Other districts include Independent School District 191 ( Burnsville–Eagan–Savage School District ), Independent School District 194 (Lakeville–Elko–New Market), Independent School District 197 (West St. Paul–Mendota Heights–Eagan) and Independent School District 200 (Hastings). Dakota County

8366-463: 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

8460-416: 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,

8554-514: 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,

8648-555: Was initially tied to the confluence of the Mississippi and Minnesota Rivers, both strategically important for United States expansion and as the convergence of the Dakota and Ojibwe nations who regarded the site as sacred. Influence shifted westward during the post-World War II settlement boom when Interstate 35 connected the western half of the county to Minneapolis and Saint Paul and bedroom communities grew. Most work outside

8742-534: 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

8836-606: 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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