4 Causes of Water Pollution Factors that contribute to water pollution can be categorized into two different groupsPoint sourcesNon-point sourcesPoint sources are the easiest to identify and controlNon point sources are ambiguously defined and harder to control
5 Point Sources Some point sources of water pollution include Waste products from factoriesWaste from sewage systemWaste from power plantsWaste from underground coalminesWaste from oil wellsThey are called point sources because they are direct sources of water pollution and can be reduced and monitored
7 Plus - the amount of farmland is declining. Recent research has shown that nutrients from septic systems are increasing throughout the watershed - development spreading into the countryside, beyond the reach of sewer systems.Stormwater runoff from urban and suburban areas is increasing as more land is developed.Urban and suburban lands currently contribute, per acre, the largest amount of nutrients to the Bay.Nitrogen from wastewater treatment plans is declining in rivers where biological nutrient removal (BNR) technology is being used. But it’s increasing in other rivers.Phosphorus from sewage treatment plans has declined sharply - results of a phosphate detergent ban.Runoff from farms is generally declining - nutrient management and runoff control techniques.Plus - the amount of farmland is declining.
8 The Chesapeake Watershed A watershed is an area of land that that drains (via streams etc) into a larger body of water.1000s of creeks, streams and rivers in Pennsylvania ultimately drain into the Susquehanna River ( = the Susquehanna River watershed) .About 64,000 square miles of land drained by hundreds of thousands of rivers, creeks and streams comprises the Chesapeake Bay watershed.The watershed includes parts of six states:New York, Pennsylvania, Delaware, Maryland, Virginia and West Virginia and also includes all of the District of Columbia.More than 15 million people live in the Bay watershed, and it's estimated that the population could grow to million people by 2020.
9 Sediment PollutionRunoff from the land adds sediment to the estuary Soil erosion caused by wave/current action along shorelines also contributes to sediment in the Bay.Sediment can smother benthic (bottom-dwelling) plants and animals e.g. oysters & clams.Suspended sediment increases turbidity, preventing light from penetrating to the leaves and stems of submerged aquatic vegetation (SAV).High concentrations of toxic materials or nutrients also may be present in sediment, which further contaminate waterways.Accumulations of sediment can clog waterways and ports, making traffic difficult or hazardous, and requiring dredging.
10 Agriculture operations can also help reduce sediment by: Sediment PollutionIn 2000, the ‘Chesapeake Agreement’ the committed local authorities to correcting sediment-related problems in the Bay.This includes trying to prevent the loss of the sediment ‘trapping’ capabilities of the lower Susquehanna River dams.Currently, these dams trap about 50 % - 70% percent of the sediment that flows downriver and prevents it from entering the Bay.Agriculture operations can also help reduce sediment by:Implementing soil conservation plans e.g. planting cover crops after harvesting and no-till farming;Constructing stream bank fencing;Planting vegetated buffers areas at the edge of crop fields; andStrip cropping - alternates different crops in rows throughout the same field.
11 Urban communities can control the amount of runoff by: Sediment PollutionIn urban areas, stormwater runoff adds to the sediment problem in waterways.Urban communities can control the amount of runoff by:Reducing impervious surfaces (e.g. roads and parking areas);Creating “rain gardens”, which are designed to capture and filter runoff from impervious sites;Planting streamside buffers zones, which allow plants to filter water and trap sediments;Creating and implementing storm water management plans – identifying and protecting protect natural areas that control runoff (and possibly restore such areas).