State & Tribal Toxin Thresholds and HAB Assessment Methods

Acute: 8
 

Short-term: 4 (up to 1 month)

Acute: 3
 

Short-term: 0.03 (up to 3 months)

10-day: 0.7 (children under 6 and other sensitive individuals), 1.6 (others)

 

Acute: 3
 

Short-term: 0.03 (up to 3 months)

10-day: 0.3 (children under 6 and other sensitive individuals), 1.6 (others)

 

CAUTION: stay away from scum and algae when swimming, don't let pets swim/eat algae/drink water, keep children away from algae in water and on the shoe, don't use water for drinking or cooking, throw away guts from fish collected in the waterbody and clean fillets with bottled or tap water, do not eat shellfish
 

WARNING: no swimming, don't let pets swim/eat algae/drink water, stay away from scum/cloudy/discolored water, don't use water for drinking or cooking, throw away guts from fish collected in the waterbody and clean fillets with bottled or tap water, do not eat shellfish
 

DANGER: Caution: no swimming, don't let pets swim/eat algae/drink water, keep children away from algae in water and on the shore, stay away from scum/cloudy/discolored water, don't use water for drinking or cooking, throw away guts from fish collected in the waterbody and clean fillets with bottled or tap water, do not eat shellfish

CAUTION= detect (< 1 ) 
 

WARNING= 20
 

DANGER= 90   

CAUTION= 1  
 

WARNING= 4
 

DANGER= 17   

CAUTION= 0.8 
 

WARNING= 6 

DANGER= 20 

0.7 (children under 6 and other sensitive individuals)

3.0 (others)

0.3 (children under 6 and other sensitive individuals)

1.6 (others)

CAUTION: keep kids and pets out of water, do not drink, avoid contact with algae, if exposed shower immediately, rinse fish with clean water and dispose of guts

DANGER: keep kids and pets out of water, do not drink, no water recreation, if exposed shower immediately, rinse fish with clean water and dispose of guts

CAUTION: Detect to 15

DANGER: >15

CAUTION: Detect to 15

DANGER: >15

CAUTION: Detect to 8

DANGER: >8

CAUTION: Detect to 8

DANGER: >8

contact DOEE at swimevents@dc.gov

or post to bloomWatch

0.7 (children under 6 and other sensitive individuals)

3.0 (others)

0.3 (children under 6 and other sensitive individuals)

1.6 (others)

Watch level: when there is evidence of a potentially toxic bloom without confirmatory data.

Alert level: toxigenic cells > 20,000; exceedance of toxin thresholds; reported human or animal illness; or as requested by tribes or waterbody managers with evidence.

Health Advisory level: toxigenic cells > 100,000; exceedance of toxin thresholds; verified human or animal illness; or as requested by tribes or waterbody managers with evidence. 

Watch level and Alert: Post signage if needed, add info to DHW map and DEQ webpage, share information through social media

Health advisory: Same as above plus Issue health advisory and send information to advisory subscribers.

Alert: N/A

Health Advisory: 15

Livestock and Pets: 0.4

Alert: 3

Health Advisory: 15

Livestock and Pets: 0.4

Alert: 1.6 (or clear presence on test strip)

Health Advisory: 8

Livestock and Pets: 0.2

Alert: N/A

Health Advisory: 8

Livestock and Pets: 0.02

Idaho Cyanobacteria Recreational Waters Response Plan

DEQ Response & Monitoring Storymap

BEACH ADVISORY: Cyanobacteria cells >100,000 cells/ml
 

BEACH CAUTION: When values exceed human advisory threshold values 
 

BEACH CLOSED: When values exceed human prohibited threshold values

HUMAN ADVISORY = 8 
 

HUMAN PROHIBITED = 30

DOGS PROHIBITED = 0.4  

HUMAN ADVISORY = 6 

HUMAN PROHIBITED = 15
 

DOGS ADVISORY = 0.5

DOGS PROHIBITED = 1  

HUMAN ADVISORY = 8

HUMAN PROHIBITED = 20

DOGS ADVISORY = 0.4

DOGS PROHIBITED = 0.8  

HUMAN ADVISORY = 0.8

 
HUMAN PROHIBITED = 3

DOGS PROHIBITED = 0.05  

0.7 (children under 6 and other sensitive individuals)

3.0 (others)

0.3 (children under 6 and other sensitive individuals)

1.6 (others)

HAB WATCH: Microcystin >4  to ≤8
 

HAB WARNING: Microcystin >8 to ≤2,000
 

HAB HAZARD: Microcystin >2,000

0.7 (children under 6 and other sensitive individuals)

3.0 (others)

0.3 (children under 6 and other sensitive individuals)

1.6 (others)

0.7 (children under 6 and other sensitive individuals)
 

3.0 (others)

0.3 (children under 6 and other sensitive individuals)
 

1.6 (others)

TIER 1 (CAUTION): Microcystins < 4 μg/L , Cyanobacterial Cell Density < 20,000 cells/mL, Anatoxin-a: no detect , Additional factors: Visual presence but no reported illness 
 

TIER 2 (CAUTION):  Microcystins 4-20 μg/L , Cyanobacterial Cell Density 20,000 - 100,000 cells/mL, Anatoxin-a: detect - 20 ug/L, Additional factors: reports of animal illness or death
 

TIER 3 (CLOSURE): Microcystins > 20 μg/L , Cyanobacterial Cell Density > 100,000 cells/mL, Anatoxin-a: > 20 ug/L , Additional factors: Reports of human illness 

TIER 1 (CAUTION): Post caution signs, visually monitor for changes
 

TIER 2 (CAUTION): Post caution signs, notify private water users and media with advisory 
 

TIER 3 (CLOSURE): Post closure signs, notify private water users and media with advisory, closures 

TIER 1: ND (Caution)
 

TIER 2: ND-20 (Caution)
 

TIER 3:>20 (Closure)

TIER 1: 4 (Caution)
 

TIER 2: 4-20 (Caution)
 

TIER 3:>20 (Closure)

TIER 1 (HAB Watch): Visual confirmation of bloom, Cyanobacterial Cell Density < 20,000 cells/mL, Microcystins 4- 8 μg/L , Cylindrospermopsin 8-15 ug/l, Anatoxin-a: 1-20 ug/L
 

TIER 2 (HAB Warning): Presence of significant cyanobacterial surface scum, Microcystins 8-2,000 μg/L , Cylindrospermopsin 15-17 ug/l, Anatoxin-a 20-90  ug/L
 

TIER 3 (HAB Danger): Microcystins > 2,000 μg/L , Cylindrospermopsin >17 ug/l, Anatoxin-a >90 ug/L

TIER 1 (HAB Watch): Post signage, Post advisory on OSE Dashboard, Issue social media release
 

TIER 2 (HAB Warning): Post signage, Post advisory on OSE Dashboard, Issue social media release, May restrict direct contact with water, issue press release
 

TIER 3 (HAB Danger):Post signage, Post advisory on OSE Dashboard, Issue press release, Close portions of the waterbody or the entire waterbody. If necessary - close adjacent land up to 100 ft from shoreline.

TIER 1: 1-20 (Watch)
 

TIER 2: 20-90 (Warning)
 

TIER 3: >90 (Danger)

TIER 1: 8-15 (Watch)
 

TIER 2: 15-17 (Warning)
 

TIER 3: >17 (Danger)

TIER 1: 4-8 (Watch)
 

TIER 2: 8-2,000 (Warning)
 

TIER 3: >2,000 (Danger)

TIER 1 (Watch):   if the cyanobacteria density is approaching 70,000 cell/mL but has not exceeded; if the cyanobacteria density is 70,000 cells/mL at only one location; or if the bloom has been reported to have passed by the time sample analysis is performed but may reoccur.
 

TIER 2 (Warning): cyanobacteria cell concentrations exceed 70,000 cells/mL at multiple locations

WATCH: Suspected HAB based on field survey OR confirmed cell counts between 20,000 – 80,000 cells/mL AND No known toxins above public health thresholds 
 

ADVISORY: Lab testing for toxins exceeds public health thresholds OR Lab confirmed cell counts above 80,000 cells/mL 
 

WARNING: Toxin (microcystin) 20 - 2000 μg/l    
 

DANGER: Toxin (microcystin) > 2000 μg/l   

WATCH: Beaches open (dependent on local health authority evaluation, assessment) use caution during primary/secondary contact activities; do not ingest water or consume fish
 

ADVISORY: Beaches closed; waterbody remains accessible; avoid primary contact, use caution for secondary contact; do not ingest water or consume fish  
 

WARNING: Beaches closed, waterbody remains accessible; avoid primary contact, recommend against secondary contact with additional evidence; do not ingest water or consume fish 
 

DANGER: Close beaches, possible closure of all or portions of waterbody and possible restrictions access to shoreline. Avoid primary contact; may recommend against secondary contact with additional evidence; do not ingest water or consume fish 

ADVISORY: 2
 

WARNING: 20-2000

DANGER: >2000

A single sample of total microcystins of 8 µg/L with no more than three exceedances within a 12-month period.

A single sample of cylindrospermopsin of 15 µg/L with no more than three exceedances within a 12-month period

CONFIRMED BLOOM: >4 to <20
 

CONFIRMED WITH HIGH TOXINS BLOOM: > 10 (open water); >20 (shoreline)

Adopted EPA Ambient Water Quality Criteria into Water Quality Standards
Microcystins: 8 µg/l for Clean Water Act water quality criterion, no more than
3 excursions (10-day assessment periods) within a single recreational season in a single year.
Cylindrospermopsins: 15 µg/l for Clean Water Act water quality criterion, no more than 3 excursions (10-day assessment periods) within a single recreational season in a single year.

TIER 1 LOW: minimal presence of a bloom, no reported illness; <8ug/L microcystins.

TIER 2 ADVISORY:  a blue-green algae bloom is present in portions of the waterbody, reports of animal illness or death, reports of human health impact; >8 to <20 ug/L microcystins.

TIER 3 WARNING:  a blue-green algae bloom covers >50% of water OR sampled exceeds 2000 ug/L microcystins; >20 or >2000 ug/L microcystins

TIER 1 LOW: Monitoring and informational sign posted at waterbody
 

TIER 2 ADVISORY: Do not swim, waterski, or tube, avoid swallowing water and watch small children and pets who may ingest water, rinse off with clean water after swimming, stay away from areas of scum when boating; ND HABs StoryMap is updated. notify local agencies, and media with advisory status
 

TIER 3 WARNING: Avoid contact with the water, avoid contact recreational activities (e.g., swimming, water skiing, kayaking and paddle boarding), do not allow pets in the water; ND HABs StoryMap is updated. notify local agencies, and media with warning status

Do not drink children under 6 and sensitive populations: 0.3

Do not drink others: 1.6

Do not drink children under 6 and sensitive populations: 0.7
 

Do not drink others: 3.0

Do not drink children under 6 and sensitive populations: 0.3
 

Do not drink others: 1.6

Do not drink children under 6 and sensitive populations: 0.3
 

Do not drink others: 1.6

0.7 (children under 6 and other sensitive individuals)
 

3.0 (others)

0.3 (children under 6 and other sensitive individuals)

1.6 (others)

0.7 (children under 6 and other sensitive individuals)
 

3.0 (others)

0.3 (children under 6 and other sensitive individuals)
 

1.6 (others)

15

Dog Information: 0.4

15

Dog Information: 0.4

8

Dog Information: 0.2

8

Dog Information: 0.02

0.7 (children under 6 and other sensitive individuals)
 

3.0 (others)

0.3 (children under 6 and other sensitive individuals)
 

1.6 (others)

ADVISORY: detect to <15

AVOID CONTACT = 15

ADVISORY = detect to <15

AVOID CONTACT = 15

ADVISORY detect to <8

AVOID CONTACT = 8

ADVISORY = detect to <8

 
AVOID CONTACT = 8

>20 ug/L (do not drink) 

>300 ug/L (do not use) 

>1.0 ug/L (do not drink)

>20 ug/L (do not use) 

 >0.3 to 20 ug/L (do not drink) 

>20 ug/L (do not use)

>0.2 ug/L (do not drink)

>3 ug/L (do not use) 

Adopted EPA Ambient Water Quality Criteria into Water Quality Standards (Regulation 61-68).
 

Swimming Advisory issued if toxins thresholds are exceeded.
 

Watch issued if potential toxin producing bloom identified  but microcystin or cylindrospermopsin less than state standards OR if identified algal species could potentially  produce algal toxins not in state standards.

Future sampling will be conducted; advisories remain in place until toxin levels are less than state WQS and there is no longer any discoloration in the water; Recreational advisories will remain in place until two (2) consecutive samples report back as less than the advisory criteria.

The assessment of toxins for purposes of Section 303(d) listing determinations for recreational uses shall be based on no more than three (3) swimming advisories in a three (3)-year 
assessment period.

Adopted EPA Ambient Water Quality Criteria into Water Quality Standards.

SCENARIO 1 (HAB not present): No HAB present and no animal or human illness

SCENARIO 2 (HAB is Evident): Risk of toxin producing algae a concern

SCENARIO 3 (HAB is Evident): Animal and/or humans displaying symptoms of exposure

SCENARIO 1 (HAB not present): Share phrase, "when in doubt, stay out".

SCENARIO 2 (HAB is Evident): Encourage humans and animals to avoid bloom, post advisory, take sample for testing

SCENARIO 3 (HAB is Evident): Notify health departments and others, post advisory, take sample for testing

CAUTION: visual reports of a bloom, reports of animal or human illness, or water samples with density or concentrations of cyanotoxins below “warning advisory” levels 
 

WARNING: Cyanobacteria cell density ≥ 20,000 cells/mL;Microcystin ≥ 8 µg/L; Cylindrospermopsin ≥ 15 µg/L ; Anatoxin-a is detected 
 

DANGER: Cyanobacterial cell density ≥ 100,000 cells/mL;Microcystin ≥ 20 µg/L; Cylindrospermopsin ≥ 17 µg/L; Anatoxin-a ≥ 60 µg/L 

CAUTION:  Issue CAUTION advisory to avoid primary contact   recreation until sample results are confirmed; Post CAUTION signs
 

WARNING: Issue WARNING advisory to avoid primary contact recreation;Post WARNING signs
 

DANGER: Issue DANGER advisory to stay away from the waterbody; Post DANGER signs; Consider CLOSURE

WARNING: >detection

DANGER:>60

WARNING: >15
 

DANGER:>17

WARNING: >8

DANGER: >20

0.7 (children under 6 and other sensitive individuals)

3.0 (others)

0.3 (children under 6 and other sensitive individuals)

1.6 (others)

WATCH (not a formal advisory):  Visual observations/reports of a possible bloom; Reports of animal or human illness; Detection of cyanotoxins or toxigenic cyanobacteria cell density below thresholds

 
WARNING: Microcystins: >8 μg/L; Cylindrospermopsin: >15 μg/L; Anatoxin-a: >15 μg/L; Saxitoxin > 8 μg/L; Toxigenic cyanobacterial cell density: >100,000 cells/mL

DANGER: Microcystins: >2,000 μg/L; Anatoxin-a: >90 μg/L; Saxitoxin > 75 μg/L; No Danger threshold currently listed for cylindospermopsin or toxigenic cyanobacterial cell density

WATCH: consider cautioning users depending on specific event, waterbody, and uses

WARNING: Issue warning advisory to avoid primary contact recreation; Sampling recommended at least weekly; post WARNING signs

DANGER: Issue danger advisory and avoid primary contact recreation; Consider closure;  Sampling recommended at least weekly; post DANGER signs

WARNING: >15

DANGER: >90

WARNING: >8

DANGER: >2000

WARNING: > 8

DANGER: >75

WARNING: >1

DANGER: >300

WARNING: >8

DANGER: >2000

Do Not Drink:
20 (children and adults)

Do Not use: 
300

Do Not Drink:
0.7 (children under 6 and sensitive individuals)

3.0 (others)
 

Do Not use: 
20

Do Not Drink:
0.3 (children under 6 and sensitive individuals)

1.6 (others)

Do Not use: 
20

Do Not Drink:
0.3 (children under 6 and sensitive individuals)

1.6 (others)
 

Do Not use: 
3

General info. signage < 80

WATCH > 80

WARNING = 300 

General info. signage < 5

WATCH > 5

WARNING = 20 

General info. signage < 6

WATCH > 6

WARNING = 20 

General info. signage < 0.8

WATCH > 0.8

WARNING = 3 

Source waters with finished water samples showing two or 

more excursions in a 3-year period above the WHO guideline for microcystin-LR (1.0 µg/L) will 

be identified as impaired and not supporting the PWS use. 

0.7 (children under 6 and other sensitive individuals)

3.0 (others)

0.3 (children under 6 and other sensitive individuals)

1.6 (others)

UNDER INVESTIGATION: Bloom may be present based on reports, including animal or human illness, but no other data collected 
 

BLOOM ADVISORY: Planktonic blooms > 20,000 cells/mL or presence of toxicogenic cyanobacteria benthic mats; Cyanotoxins are unknown or below advisory thresholds.
 

TOXIN ADVISORTY: toxin concentrations exceed recreational use thresholds.

UNDER INVESTIGATION: Add waterbody to WyoHCBs.org webmap and monitor. Monior until data supports movement to another tier or until December 31
 

BLOOM ADVISORY: Post signs, Add waterbody to WyoHCBs.org webmap, Include waterbody in listserv email, Monitor until data supports movement to another tier or until December 31
 

TOXIN ADVISORY: Post signs, Add waterbody to WyoHCBs.org webmap, Include waterbody in listserv email, Monitor until data supports movement to another tier or until December 31