question: how do they dye the Chicago river?
comment: The city and parade organizers use an eco-friendly vegetable based powder that is actually orange until it mixes with water. The morning of St. Patrick's Day, they go out in a couple boats: one large boat that dumps the powder into the river and a smaller boat that follows mixing the powder and water. It only lasts about 5 hours though because of the river flow.
passages: Section::::Dyeing the river.
  
  Section::::Dyeing the river.:St. Patrick's Day.
  
  As part of a more than fifty-year-old Chicago tradition, the Chicago River is dyed green in observance of St. Patrick's Day. The actual event does not necessarily occur on St. Patrick's Day and is scheduled for the Saturday before March 17, unless the 17th falls on a Saturday (when the event takes place on St. Patrick's Day).
  
  The tradition of dyeing the river green arose by accident when plumbers used fluorescein dye to trace sources of illegal pollution discharges. The dyeing of the river is still sponsored by the local plumbers union.
   The city has many different Saint Patrick's Day celebrations, the most famous being the dyeing of the Chicago River. Each year, the city hosts a parade downtown, which is preceded by the dyeing of the Chicago River. The dyeing of the river involves thousands of people lining the banks of the river and watching as a boat releases dye into the river and turns the river a kelly green color. The Chicago Journeymen Plumbers Union Local 130 has historically sponsored the river dyeing and knows the secret to the dye mix.
   In 2009 First Lady Michelle Obama, a Chicago native, requested that the White House fountains be dyed green to celebrate St. Patrick's Day.
  
  Section::::Dyeing the river.:Chicago Cubs rally.
  
  For the Chicago Cubs rally and parade for their 2016 World Series Championship celebrations, the river was dyed Cubs blue.
  
  Section::::Monitoring the impact of extreme weather events on the Chicago District.
   Section::::Course.:Main Stem.
   Section::::History.:Early improvements.
   The Leaf River served as a trade route in the area before roads and trails were widely developed. It is recorded that traders made regular trips to people living near the river bringing with them supplies from Pascagoula. Legend says that one of these traders buried his profits, several thousand dollars in Spanish coins, near the banks of the Leaf River. The coins were later found in about 1854.
  
  Section::::Alleged pollution.
   Through the 1980s, the river was quite dirty and often filled with garbage; however, during the 1990s, it underwent extensive cleaning as part of an effort at beautification by Chicago Mayor Richard M. Daley.
  
  In 2005, researchers at the University of Illinois at Urbana–Champaign created a three-dimensional, hydrodynamic simulation of the Chicago River, which suggested that density currents are the cause of an observed bi-directional wintertime flow in the river. At the surface, the river flows east to west, away from Lake Michigan, as expected. But deep below, near the riverbed, water seasonally travels west to east, toward the lake.
   The Environmental Protection Agency (EPA) outlawed the use of fluorescein for this purpose, since it was shown to be harmful to the river. The parade committee has since switched to a mix involving forty pounds of powdered vegetable dye. Though the committee closely guards the exact formula, they insist that it has been tested and verified safe for the environment. Furthermore, since the environmental organization Friends of the Chicago River believes the dye is probably not harmful, they do not oppose the practice.
   The river is represented on the Municipal Flag of Chicago by two horizontal blue stripes. Its three branches serve as the inspiration for the Municipal Device, a three-branched, Y-shaped symbol that is found on many buildings and other structures throughout Chicago.
  
  Section::::Course.
   Section::::Description.:Landscape.
   Section::::Course.:Discharge.
  
  The United States Geological Survey monitors water flow at a number of sites in the Chicago River system. Discharge from the North Branch is measured at Grand Avenue; between 2004 and 2010 this averaged per second. During the winter months as much as 75% of the flow in the North Branch is due to the discharge of treated sewage from the North Side Water Reclamation Plant into the North Shore Channel. Flow on the Main Stem is measured at Columbus Drive; between 2000 and 2006 this averaged per second.
  
  Section::::History.
  
  Section::::History.:Name.
   Near the boat dock and the mule corral are thirteen full-size steel silhouettes representing ten passengers who rode a canal boat between 1848 and 1853 and three men who worked on the packet boats. The silhouettes and their labels introduce you to mule driver Wild Bill Hickok, Abraham Lincoln and his family, Chief Shabonna, and others not so well known.
   Section::::Lawman.
   Future plans and recent activity have started to reshape the river. In the fall of 2009, dredging removed of sediment contaminated with PCBs and PAHs near the harbor. In addition to improved environmental conditions, the dredging created a safer, deeper, and more navigable river.
   The name Chicago derives from 17th century French rendering of a Native American term for ramps ("Allium tricoccum"), a type of edible wild leek, which grew abundantly near the river. The river, and its region, were named after this plant.
  
  Section::::History.:Exploration and settlement.
   Finally, in 1900, the Sanitary District of Chicago, then headed by William Boldenweck, completely reversed the flow of the Main Stem and South Branch of the river using a series of canal locks, increasing the river's flow from Lake Michigan and causing it to empty into the newly completed Chicago Sanitary and Ship Canal. In 1999, this system was named a "Civil Engineering Monument of the Millennium" by the American Society of Civil Engineers (ASCE). Before this time, the Chicago River was known by many local residents of Chicago as "the stinking river" because of the massive amounts of sewage and pollution that poured into the river from Chicago's booming industrial economy.
   Section::::Processes.:Beam dyeing process.
   The 18-acre FMC Corporation (Fridley Plant) is a United States Environmental Protection Agency Superfund site located in Anoka County, Minnesota, several hundred feet east of the Mississippi River. Solvents, paint sludge, and plating wastes were generated and disposed of in an on-site dump from the 1940s until 1969. Minnesota Pollution Control Agency (MPCA) staff sampled site surface and groundwater in the early 1980s and confirmed that ground and surface water were contaminated by industrial solvents. In the 1980s, solvents from the site were detected in the city of Minneapolis drinking water system intake that is located downgradient of where the FMC site groundwater contaminant plume enters the river.
   According to "Chicago Wilderness" Magazine, as the Des Plaines River runs through four Illinois counties, it "changes from prairie creek to a suburban stream, to a large urbanized river, to a major industrial waterway."
   Section::::Pollution and remediation efforts.
   Section::::Production.:Casting.
   Section::::History.:Draining the riverine wetland.
   Section::::Mississippi River designs.
   Dye Water
  
  The Dye Water () is a river in the Lammermuir Hills in the Scottish Borders area of Scotland. It rises in the Hope Hills, continues along the East Lothian boundary, a mile north east of Seenes Law, then east to Longformacus. The Dye Water joins the Whiteadder Water and completes its 12.5 mile journey.
  
  The Sir Walter Scott Way and the Southern Upland Way long distance footpaths also pass through Longformacus.
  
  Section::::See also.
  
  BULLET::::- List of places in the Scottish Borders
  
  BULLET::::- List of places in Scotland
  
  Section::::External links.
   BULLET::::- Bleaching and dyeing is done in copper vessels. 20 to 30 grams of dye powder is used per kg of yarn, which is mixed in water. Acid is used for fixation. Coconut oil is used to give a soft finish to silk. The yarns are dipped in the dye bath for 30 to 40 minutes using copper rods. It is then removed, washed a few times in water and then squeezed. The yarn is dried in the shade.
  
  Section::::Color dyeing.:Traditional colours.
  
  The dominant traditional colours of vegetable dyes included:
  
  BULLET::::- Pophali - yellow
  
  BULLET::::- Red
  
  BULLET::::- Lavender
  
  BULLET::::- Purple
  