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DR. PAUL A. BUKAVECKASVIRGINIA COMMONWEALTH UNIVERSITY
Developing water quality standards to Protect the James
River against Impacts from Algal Blooms.
http://wp.vcu.edu/jamesriver/
Today’s Panel
The TMDL process: reductions in nutrient loads to reach restoration goals.
Water Quality Criteria: their role in establishing nutrient reduction targets.
Algal Blooms in the James River Estuary: causes and threats to designated uses.
My Presentation: assessing risk from algal blooms in the James.
10/15
15/22
12/10
15/23
Current James River CHLa standards (µg/L) based on season (spring/summer) & salinity Attainability (load reductions) based on CB
model; estimated cost to achieve = $1-2 billion. VA response: “let’s make sure first”
Are standards defensible? Are model forecasts of attainability
reliable?
James River Algal Blooms Study
6-year (2012-2017), $3 million study funded by Commonwealth of Virginia (administered by Department of Environmental Quality). understand when, where, and why of algal blooms. improve water quality models – specifically, their
reliability to predict CHLa under changing nutrient load scenarios.
assess whether current CHLa-based regulatory standards are protective of designated uses. How much CHLa is ‘too much’?
Changes to regulatory standards, or modeling framework, directly affect allowable nutrient loads.
Science Advisory Panel
Evaluate existing numeric CHLa criteria for the James. Are they protective of designated uses?
Assess modeling framework: Can model performance be improved to reliably predict responses to management scenarios?
Data Collection (2012-14):• When, where, why of algal
blooms.• Effects on water quality,
human health and aquatic life resources.
Modeling Team: model development, calibration and simulations of nutrient load scenarios.
Deleterious Effects of Algal Blooms
Water quality transient (night-time) oxygen minima
elevated pH: daytime maxima
Water Clarity: algal contributions to suspended particulate matter
Phytoplankton metrics Community indices: PIBI evenness, richness
Harmful algal abundance & Algal Toxins
Water Quality Standards for the James
Are current CHLa standards protective of designated uses (aquatic life, etc.)? A dual-probability approach:•What is the risk of deleterious effects at a given CHLa concentration?•What is the likelihood of exceeding that CHLa concentration if current CHLa standard is attained?
CHLa p (DO<5)
p (CHLa)
p (combined)
0-30 1% 50% 0.5%
31-60 10% 35% 3.5%
61-90 50% 15% 7.5%
Effects of Algal Blooms on Water Quality
Risk to water quality conditions from daytime pH maxima exceeding 9.0 in relation to CHLa for the tidal fresh and oligohaline segments of the James. Vertical lines denote current criteria.
pH > 9
Summer
Spring
Phytoplankton Community Structure
Phytoplankton Index of Biotic Integrity in relation to CHLa and occurrence of communities in ‘least degraded’ (PIBI>2.67) state.
Stressors, Criteria & Risk
Stressor (e.g., CHLa)
Thr
eats
to
Des
igna
ted
Use
s (e
.g.,
low
DO
)
idealstandard
Assessing Risk to Aquatic Life Designated Uses based on Combined Probability Approach
Tidal Fresh
Polyhaline
Mesohaline