the mississippi river empties into the gulf of mexico at lake itasca.
the mississippi river empties into the gulf of mexico at lake itasca.
where does the mississippi river empty into the gulf of mexico?
lake itasca
the modern mississippi river delta formed over the last approximately 4,500 years as the mississippi river deposited sand, clay and silt along its banks and in adjacent basins. the mississippi river delta is a river-dominated delta system, influenced by the largest river in north america. the shape of the current birdfoot delta reflects the dominance the river exerts over the other hydrologic and geologic processes at play in the northern gulf of mexico. prior to the extensive leveeing of the mississippi river that began in the 1930s, the river avulsed its course in search of a shorter route to the gulf of mexico approximately every 1,000–1,500 years. the prehistoric and historic delta lobes of the mississippi river delta have influenced the formation of the louisiana coastline and led to the creation of over of coastal wetlands.
mississippi river delta
the area of temporary hypoxic bottom water that occurs most summers off the coast of louisiana in the gulf of mexico is the largest recurring hypoxic zone in the united states. the mississippi river, which is the drainage area for 41% of the continental united states, dumps high-nutrient runoff such as nitrogen and phosphorus into the gulf of mexico. according to a 2009 fact sheet created by noaa, "seventy percent of nutrient loads that cause hypoxia are a result of this vast drainage basin". which includes the heart of u.s. agribusiness, the midwest. the discharge of treated sewage from urban areas (pop. c 12 million in 2009) combined with agricultural runoff deliver c. 1.7 million tons of phosphorus and nitrogen into the gulf of mexico every year. even though iowa occupies less than 5% of the mississippi river drainage basin, average annual nitrate discharge from surface water in iowa is about 204,000 to 222,000 metric tonnes, or 25% of all the nitrate which the mississippi river delivers to the gulf of mexico. export from the raccoon river watershed is among the highest in the united states with annual yields at 26.1 kg/ha/year which ranked as the highest loss of nitrate out of 42 mississippi subwatersheds evaluated for a gulf of mexico hypoxia report. in 2012, iowa introduced the iowa nutrient reduction strategy which, "the iowa nutrient reduction strategy is a science and technology-based framework to assess and reduce nutrients to iowa waters and the gulf of mexico. it is designed to direct efforts to reduce nutrients in surface water from both point and nonpoint sources in a scientific, reasonable and cost effective manner." the strategy continues to evolve, using voluntary methods to reduce iowa's negative contributions through outreach, research, and implementation of nutrient holding practices. in order to help reduce agricultural runoff into the mississippi basin, minnesota passed "mn" statute 103f.48 in 2015, also known as the "buffer law", which was designed to implement mandatory riparian buffers between farmland and public waterways across the state of minnesota. the minnesota board of water and soil resources (bwsr) issued a january 2019 report stating that compliance with the 'buffer law' has reached 99%.
dead zone (ecology)