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.

Mean CHLa in relation to current criteria for tidal fresh James.

Spring

Summer

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