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Harmful Algal Bloom (HAB): Lady Bird Lake B r e n t B e l l i n g e r, P h . D. W a t e r s h e d P r o t e c t i o n D e p a r t m e n t 1 1 / 1 7 / 2 0 2 0 C I T Y O F A U S T I N W A T E R S H E D P R O T E C T I O N D E P A R T M E N T What Happened in 2019? D o g d e a t h s a t R e d B u d a n d A u d i t o r i u m s h o re s O n l y o b s e r v e d i n L a d y B i r d ( n o m o r t a l i t i e s re p o r t e d i n 2 0 2 0 ) C I T Y O F A U S T I N W A T E R S H E D P R O T E C T I O N D E P A R T M E N T HAB types P l a n k t o n i c ( s i n g l e c e l l s i n wa t e r c o l u m n ) – M o s t C o m m o n Lake Erie, Des Moines C o h e s i v e m a t s ( b e n t h i c , f l o a t i n g m a t r i x o f f i l a m e n t s ) L a d y B i r d L a k e C I T Y O F A U S T I N W A T E R S H E D P R O T E C T I O N D E P A R T M E N T Cyanobacteria P r i m i t i v e ! • Over 3 billion years old • First photosynthetic organisms; changed Earth’s atmosphere – the “Great Oxygenation Event” • 6,000+ estimated species C a p a b l e o f p ro d u c i n g s e c o n d a r y m e t a b o l i t e s • Geosmin, 2-methylisobroneol (MIB) – linked to taste-and-odor issues in the drinking water • Toxins C I T Y O F A U S T I N W A T E R S H E D P R O T E C T I O N D E P A R T M E N T Cyano. Pop. Dynamics Se asonality typic al (summe r) ( D a t a f r o m L a k e A u s t i n ) “T hree pillars” to a toxic bloom • L o w flow s, lack of r ain, minimal turbulen c e • Hot • A b undant N utrien ts (N , P ) C I T Y O F A U S T I N W A T E R S H E D P R O T E C T I O N D E P A R T M E N T The 2019 LBL Event A 3d ave 7d ave D isc harge rates • L a t e J u l y d r o p i n d i s c h a r g e c o i n c i d e d w i t h b l o o m a n d t o x i n s e v e n t B 2016-2018 3d ave 2019 3d ave ) s m c ( e g r a h c s D m a D i r e l l i M m o T 40 30 20 10 0 40 30 20 10 0 C I T Y O F A U S T I N W A T E R S H E D P R O T E C T I O N D E P A R T M E N T 180 200 220 240 260 280 300 320 Julian Day The 2019 LBL Event A 3d ave 7d ave D isc harge rates • L a t e J u l y d r o p i n d i s c h a r g e c o i n c i d e d w i t h b l o o m a n d t o x i n s e v e n t • Av e w a s l o w e r t h a n p r e v i o u s 3 - y e a r p e r i o d ) s m c ( e g r a h c s D m a D i r e l l i M m o T 40 30 20 10 0 40 30 20 10 0 B 2016-2018 3d ave 2019 3d ave C I T Y O F A U S T I N W A T E R S H E D P R O T E C T I O N D E P A R T M E N T 180 200 220 240 260 280 300 320 Julian Day The 2019 LBL Event Wa t e r Te m p s >30°C weekend of dog deaths • • N u t r i e n t s Significantly higher NH3, NOx in 2019 and abundant TP at sites where HAB/dog deaths occurred • Elevated compared to previous years (based on routine monitoring) C I T Y O F A U S T I N W A T E R S H E D P R O T E C T I O N D E P A R T M E N T Period 2019 Project Bloom NH3 (μg/L) 32.5 ± 16.9 NOx (μg/L) 253.1 ± 181.4 21.9 ± 15.0 TP (μg/L) 2016 – 2018 Monitoring 8.0 ± 0.0 199.0 ± 198.0 14.1 ± 9.3 2019 Monitoring 19.1 ± 18.2 476.0 ± 488.0 26.4 ± 15.5 What Made 2019 Different? • Zebra mussels (new) • Alter water chemistry • Promote dense benthic growth • Large flooding, runoff, depositional event (Fall 2018) (new) • Altered sediment and water chemistry? • Climate change (new) • Dog waste (old) • (sorta) Low flows (old) • But now coupled with new drivers! ) s m c ( e g r a h c s D m a D i r e l l i M m o T . e v A 30 25 20 15 10 5 0 C I T Y O F A U S T I N W A T E R S H E D P R O T E C T I O N D E P A R T M E N T 2012-2015 2019 160 180 200 220 240 260 280 300 Julian Day Forecasting and Prevention (?) “ H A B s c a n n o t e a s i l y b e e l i m i n a t e d o r p r e v e n t e d , b u t t h e y c a n b e m o n i t o r e d a n d p r e d i c t e d , a n d t h e p o t e n t i a l l y n e g a t i v e c o n s e q u e n c e s c a n b e m a n a g e d a n d m i t i g a t e d . C h a n g e s i n h u m a n a c t i v i t i e s a n d b e h a v i o u r c o u l d a l s o c o n t r i b u t e t o p r e v e n t o r m i n i m i z e c e r t a i n H A B S a n d t h e i r d e l e t e r i o u s e f f e c t s . ” K u d e l a e t a l . ( 2 0 1 5 ) I O C / U N E S C O R e p o r t W P D A p p r o a c h t o M o n i t o r i n g , M o d e l i n g , M i t i g a t i o n • Weekly WQ sampling; Daily Discharges; Hourly Temps; Toxin abundances; Species Library (DNA fingerprinting) Developing Models • Treatment and preventative options being explored • • • • • • Aeration Alum Biochar Physical or Mechanical Removal Chemicals (absolute last resort) Unclear how effective any of these treatments would be in reservoir C I T Y O F A U S T I N W A T E R S H E D P R O T E C T I O N D E P A R T M E N T Questions? B rent B elling er, P h.D., Environm enta l Scientist Senior brent.belling er@ a ustintexa s.g ov C I T Y O F A U S T I N W A T E R S H E D P R O T E C T I O N D E P A R T M E N T