Nutrient criteria for Iowas Waters

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Nutrient criteria for Iowas Waters
Jack Riessen, P.E. Iowa DNR
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Why do we need nutrient criteria?

• Nitrogen (N) and phosphorus (P) as well as other
  nutrients are essential for life, a waterbody
  without nutrients would be a sterile, lifeless
  water.
• Nutrients have purposely been added to increase
  productivity of lakes and streams
• But, there can be too much of a good thing
  nutrient enrichment.
• Ideally, nutrient criteria need to define when
  nutrients cease to be a benefit and become a
  problem

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Problems often linked to nutrient enrichment

• Nuisance levels of algae and aquatic vegetation.
• Increased turbidity - sight feeding fish,
  aesthetics, water safety, limits growth of
  submerged aquatic vegetation
• Low levels of dissolved oxygen, high levels of
  ammonia results of organic decomposition
• Increased drinking water treatment costs -
  formation of disinfection by-products (e.g.,
  THMs) in drinking water, taste and odor effects
  of algae
• Imbalance of aquatic species
• Toxic algae and cyanobacteria (blue green algae)

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Avenue of the Saints Lake 2006
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Turkey River August 2001
The result of all the right things sunshine,
adequate nutrients, low turbulence, warm water,
etc. - happening at the same time. Right before
this bloom, the water was very clear.
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The national nutrient picture

• Toxic Pfisteria late 1990s
• East coast estuaries fish kills, human health
  effects
• Linked to nutrient enrichment
• Gulf hypoxia the so-called dead zone
• Increase in areal extent, frequency
• Linked to increased nutrients from Upper
  Mississippi Basin
• Drinking water
• Nitrate levels linked to row crop agriculture
• Disinfection byproducts
• States routinely list nutrient enrichment as a
  leading cause of waterbody impairment

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The national nutrient picture

• EPAs Mississippi River/Gulf of Mexico Nutrient
  Task Force - 1997
• National Science and Technology Council -
  assessment of Gulf hypoxia - 1997
• Harmful Algal Bloom and Hypoxia Research and
  Control Act 1998
• Authorized research on HABs - causes, effects,
  etc.
• Called for action plan to control Gulf hypoxia
• Clinton/Gore Clean Water Action Plan - 1998
• Catalysts for national strategy to address
  nutrient enrichment impacts
• Gulf Hypoxia Action Plan called for 30 N load
  reduction
• EPA to develop guidance values for nutrients
  for lakes, streams and wetlands
• States to adopt water quality criteria for
  nutrients by end of 03

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Its 2007, where are we now?

• Gulf Hypoxia Action Plan
• Reassessment of the science
• N v. P?
• How much reduction of N (or P) needed?
• Role of hydrology, e.g. plumbing of lower Miss
• Relatively little funding to implement any
  solutions
• IDALS currently taking lead for Iowa
• Upper Basin states most active

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Its 2007, where are we now?

• State nutrient criteria
• Nutrient criteria guidance documents developed
  and released late 2000.
• Relatively few states have adopted numeric
  nutrient criteria
• Relatively few will have criteria in place by
  2008
• Question Why havent more states made progress
  on nutrient criteria?

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Nutrient criteria present a different, and very
significant, challenge compared to conventional
water quality criteria
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Example of conventional criterion dissolved
oxygen

• Aquatic life needs dissolved oxygen (DO) to
  survive
• Science shows many fish and aquatic organisms
  need DO levels above 5 mg/L (ppm) to survive.
  Trout are more even sensitive.
• DO criteria adopted to protect most sensitive
  aquatic species
• 5 mg/L for warmwater streams
• 7 mg/L for coldwater (trout) streams
• DO criteria reflect direct link, a cause and
  effect relationship, between DO levels and health
  of aquatic life
• For nutrients (N and P), there is not this direct
  link (with exception of ammonia and nitrate)

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EPAs rationale for asking states to develop
nutrient criteria
High nutrient levels
High levels of algae, aquatic plants

• Waterbody Impairment
• Turbid waters
• Poor species diversity
• Low DO, high ammonia
• Toxic algae (blue greens)

How strong are these relationships? Weak
relationships undermine rationale for nutrient
criteria.
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• Some of the basics
• Algae
• Law of the Minimum
• EPAs Nutrient Guidance
• What does Iowas monitoring data show?
• Some questions and challenges in setting
  reasonable nutrient criteria

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Algae

• Algae a general term for a very diverse group
  of organisms
• Over 17,000 species single-celled and
  multi-celled seston and benthic green, brown,
  red, golden, diatoms, etc. all different shapes
  and sizes
• Ubiquitous - terrestrial and aquatic systems,
  found in lakes, rivers, estuaries and oceans
  around the world
• Blue green algae - Cyanobacteria
• Not true algae but photosynthetic bacteria
• Have been around for over 3 billion years
• Along with aquatic plants, form the base of the
  aquatic food chain
• Photosynthetic, create organic matter from
  inorganic nutrients (primary producers)
• Life as we know it would not exist without algae

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• A typical aquatic food web

• Nutrients recycle in these systems

Source Water on the Web

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Measuring algae

• Chlorophyll a
• Photosynthetic pigment found in true algae as
  well as cyanobacteria, about 1 to 2 of dry
  weight of algae
• Does not differentiate between species of algae
  and cyanobacteria
• Cell counts and biovolume provides genus or
  species specific data
• Turbidity High levels of suspended algae affect
  light scattering properties (i.e., clarity) of
  water
• Secchi disk and turbidity meter
• Not good indicator of algal biomass when lots of
  inorganic solids (silts, clays) in water.

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The Law of the Minimumthe rationale for
assuming nutrient reduction will reduce the
level of algae and improve water quality

• All organisms require a variety of nutrients
• For plants and algae, generally in order of C, N,
  P and K
• N and P needed in relatively greater amounts
  compared to others
• von Liebig 19th century chemist
• Only by increasing nutrient most scarce in
  relation to need was crop production increased
• Corollary Limiting the nutrient most scarce in
  relation to need, production will be limited or
  capped
• Assumption is that by limiting N and/or P levels
  in water, algal biomass will be limited
  frequency and severity of nuisance blooms will be
  reduced.
• P, not N, typically the limiting nutrient in
  freshwater systems
• Available supply of P will be used up long before
  N
• N may play role in some freshwater systems

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EPA Nutrient Guidance
EPA has published guidance for states to use in
establishing nutrient water quality standards
lakes and streams and rivers.
Cornbelt and Northern Great Plains
14 Nutrient Ecoregions
Guidance suggests states establish criteria for
TN, TP, chlorophyll a and turbidity (e.g.,
Secchi disk depth)
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Guidance outlines three methods to establish
nutrient criteria

• Reference water approach basis for values
  provided in guidance documents.
• Based on statistical properties of monitoring
  data (i.e., 25th or 75th percentile of available
  monitoring data)
• Does not prove cause and effect relationships
  between nutrients and adverse effects
• Predictive relationships
• Looks at cause and effect relationships between
  nutrient levels and algal biomass, DO, NH3, etc.
• Analysis of monitoring data - correlation,
  regression, breakpoints, etc.
• Published works

States should take a weight of evidence approach
RTAGs regional workgroups, benchmark values
for TN,TP and chl a for lakes, now working on
benchmarks for streams
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What does the monitoring data show?

• Iowa waters have relatively high levels of N and
  P as well as chlorophyll a high turbidity
• If we would adopt the values in the EPA guidance
  documents or the RTAG benchmarks, about 90 of
  our waters would end up on the impaired waters
  list.
• Concentrations of N, P and chl a are highly
  variable
• Waterbody to waterbody spatial variablity
• Within a waterbody temporal variablity
• Difficult to measure compliance with a nutrient
  criterion, detect trends
• Most of the N and P in the water come from
  nonpoint sources like agriculture.
• Point sources like wastewater plants less than
  10 of N and less than 20 of P on a statewide
  basis.

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What does the monitoring data show?

• Summertime turbidity is caused by a combination
  of algae and inorganic suspended solids (e.g.,
  suspended silts and clays)
• Turbidity is not a good measure of algal biomass
• Iowa lakes are very productive fisheries
• Above average growth rates
• The fish are healthy - few abnormalities,
  lesions, etc. that are indicative of stressors
  like low DO
• Diversity can be a problem

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What does the monitoring data show?

• Most Iowa lakes have very high proportions of
  cyanobacteria v. true algae
• Even the very best have high cyanbacteria
• Factors that determine elusive
• Cyanobacteria have number of characteristics that
  may provide competitive advantage over true algae
• Nuisance or worse blooms possible in just about
  any Iowa waters
• Some of Iowas best lakes have occasional
  nuisance or worse algal blooms
• Brushy Ceek and Threemile, two relatively low-P
  lakes, both had severe nuisance blooms in 05

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What does the monitoring data show?

• Nitrogen is rarely (if ever) a limiting nutrient
• Generally, more than enough N available
• N reduction, per se, will not accomplish much in
  reducing algal biomass
• Phosphorus only occasionally may be a limiting
  nutrient
• Other factors play a role, P availability not
  usually a problem
• The big picture is we have a lot of N and P in
  our water
• Difficult to establish cause and effect
  relationships when neither N nor P are limiting
  nutrients
• Data suggests very significant reductions in P
  (or N) might be needed to achieve any water
  quality improvement

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What does the monitoring data show?

• In summary
• We have very productive waters lots of N and
  P
• N and P levels vary considerably over time
• 90 (or more) of our waters would end up on the
  impaired waters list if EPA guidance (or RTAG)
  values were adopted
• P seldom limits algal biomass, significant
  reductions needed for waters to be P-limited
• Difficult to establish clear-cut cause and effect
  relationships between P (or N) and aquatic impacts

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Lake nutrient criteria questions

• Will nutrient reductions improve water quality?
• If so, what level of reductions are needed to see
  a significant effect?
• Should criteria reflect the ideal (e.g. the
  RTAG benchmarks) or what is reasonably
  achievable?
• Can we determine with any confidence what levels
  of nutrient reductions are reasonably achievable?
• How can attainability be incorporated into
  nutrient standards?
• If N is not a limiting nutrient, can we justify
  an N criterion?

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Lake nutrient criteria questions

• Should cyanobacteria dominance be a
  consideration?
• Do we establish different groups of lakes and
  streams and rivers with different standards for
  each group?
• How will EPA address state-to-state
  inconsistencies? Gulf hypoxia N reductions?
• How do we measure compliance with nutrient
  criteria with a reasonable level of confidence?
• Median, mean, or other parameter?
• Minimum number of samples?
• Summer, all season?

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Technical advisory committee (TAC) formed to
address technical issues

• Committee comprised of technical experts, not
  general stakeholder group
• Intent is to provide the sound science behind
  any eventual criteria
• Consensus based, but minority opinions need to be
  recognized
• No easy answers, some policy decisions will be
  needed. Policy decisions are role of EPC but
  recommendations of TAC will be important
• Initially focusing on lakes
• Rivers and streams will make lakes look easy
• Wetlands will make rivers and streams look easy.

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Questions?