Eutrophication : a major issue

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Eutrophication a major issue
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- What is eutrophication? - Step by step
eutrophication process - Effects on water
quality, treatment costs, compliance and
recreational activities - What is the
situation in Puerto Rico? - Can the
eutrofication be reversed? - actual lake
restoration process - how soon can we
see results? - what are the benefits?
- How much is the cost? - funding option
- is there a lease option? - Do all
this makes sense ?
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What is Eutrophication?
Eutrophication is a process whereby water bodies,
such as lakes, estuaries, or slow-moving streams
receive excess nutrients that stimulate excessive
plant growth (algae, periphyton attached algae,
and nuisance plants weeds). This enhanced plant
growth, often called an algal bloom, reduces
dissolved oxygen in the water when dead plant
material decomposes and can cause other organisms
to die. Nutrients can come from many sources,
such as fertilizers applied to agricultural
fields, golf courses, and suburban lawns
deposition of nitrogen from the atmosphere
erosion of soil containing nutrients and sewage
treatment plant discharges.
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Step by step eutrophication process
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Oligotrophic lake with a low level of nutrients.
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Artificial input of nutrients from run-off and
discharge of effluent.
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Eutrophic lake with a high level of nutrients.
Phosphorus is usually the bio-limiting element
in freshwater lakes.
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Rapid growth of algae and other biomass resulting
in a decrease in the concentration of dissolved
oxygen.
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Turbidity (cloudiness) of water increases as does
rate of sedimentation.
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Increased growth of rooted plants such as reeds.
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Algal blooms during the Summer months. Note that
dissolved oxygen levels are at their lowest at
night when plants respire rather than
photosynthesis.
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Development of anoxic conditions and release of
noxious gases such as hydrogen sulphide,
thioalcohols and ammonia.
Eutrophication process, the movie summary
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Effects on water quality, treatment costs,
compliance and recreational activities
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Effects on water quality

• Bad taste and odor some of the algal species
  that "bloom" produce toxins (geosmin, MIB), water
  taste and odor deteriorates.
• Oxygen depletion penetration of light into the
  water is diminished. This occurs because the
  algae forms mats as a result of being produced
  faster than they are consumed. Diminished light
  penetration decreases the productivity of plants
  living in the deeper waters and hence their
  production of oxygen.
• DBP precursors As the water becomes depleted in
  oxygen, the abundant algae and fish die and
  decompose, further oxygen is consumed by this
  process.
• Under anoxic conditions iron, manganese, ammonia
  and phosphorous are released into the water
  column, anaerobic bacteria flourish, producing
  hydrogen sulfide.

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Effects on treatment costs and compliance

• Bad taste, odor, and high organics increase
  operational costs
• Compliance with local and federal regulations
  becomes more difficult to achieve

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Effects on recreational activities

• Recreation Lowered oxygen results in the death
  of fish that need high levels of dissolved
• oxygen "DO"), such as trout, salmon and
  other desirable sport fish. The community
• composition of the water body changes, with
  fish that can tolerate low DO, such as carp
• predominating.
• Changes in fish communities have ramifications
  for the rest of the aquatic ecosystem like the
• explosion of mosquitoes.

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What is the situation in Puerto Rico?
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EQB Report 2002
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Can the eutrophication be reversed?

• actual lake restoration process, how soon can we
  see results?, what are the benefits?

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How much is the cost? -
funding option - is there
a lease option?
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How much is the cost?

• size and depth of lake
• how fast we want to achieve goals
• need of biological treatment
• available water quality data
• bathymetric study
• cheaper than dredging
• more effective than inflow control
• reduce operational costs
• more than 2,000 installations

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Funding options, is there a lease option?
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Do all this makes sense?