State & Tribal Toxin Thresholds and Assessment Methods
This page offers a compilation of the cyanotoxins thresholds used by state and Tribal programs to make advisory decisions for drinking water and recreational uses.
State Toxin Thresholds
The following table list toxin thresholds (for anatoxin, microcystins, cylindrospermopsin, and saxitoxins) being used by states to make advisory decisions for drinking water (DW) or recreational uses (REC). Units are in ppb or micrograms per liter. Only thresholds for which there was publicly accessible information available are listed and the links are provided in the final column. Many states used the USEPA Health Advisory (EPA HA) values for microcystin and cylindrospermopsin for drinking water advisories or USEPA Ambient Water Quality Criteria (EPA AWQC) for recreational advisories and those are noted. USEPA values are shown at the bottom of the table.
Table 1
State Toxin Thresholds for Drinking Water and Recreation
| Anatoxin-A | Microcystins | Cylindrospermopsin | Saxitoxins | ||||||||
| State | Application | Threshold Description | DW (ug/L) | REC (ug/L) | DW (ug/L) | REC (ug/L) | DW (ug/L) | REC (ug/L) | DW (ug/L) | REC (ug/L) | Citation/Link |
| AL |
DW |
No Thresholds | - | - | - | - | - | - | - | - | |
| AL | REC | No Thresholds | - | - | - | - | - | - | - | - | |
| AK | DW | No Thresholds | - | - | - | - | - | - | - | - | |
| AK | REC | No Thresholds | - | - | - | - | - | - | - | - | |
| AZ | DW | No Thresholds | - | - | - | - | - | - | - | - | |
| AZ | REC | No Thresholds | - | - | - | - | - | - | - | - | |
| AR | DW | No Thresholds | - | - | - | - | - | - | - | - | |
| AR | REC | Single Tier Recreational Value | - | - | - | EPA AWQC | - | EPA AWQC | - | - | Harmful Algal Blooms Management Plan |
| CA | DW | 1-day DW Value | 8 | - | 3 | - | 3 | - | 0.5 | - | Notice of Availability of Acute Notification Level Recommendations for Four Cyanotoxins in Drinking Water |
| CA | REC | No Advisory Value | - | Non-detect | - | <0.8 | - | <1 | - | - | California Voluntary Guidance for Response to HABs in Recreational Inland Waters |
| CA | REC | Caution Value | - | detect | - | 0.8 | - | 1 | - | - | California Voluntary Guidance for Response to HABs in Recreational Inland Waters |
| CA | REC | Warning Value | - | 20 | - | 6 | - | 4 | - | - | California Voluntary Guidance for Response to HABs in Recreational Inland Waters |
| CA | REC | Danger Value | - | 90 | - | 20 | - | 17 | - | - | California Voluntary Guidance for Response to HABs in Recreational Inland Waters |
| CO | DW | Single Tier Drinking Water Value | - | - | 0.3 | - | 0.7 | - | - | - | Harmful algal bloom monitoring guidance |
| CO | REC | Caution Value | - | Detect to 15 | - | Detect to 8 | - | Detect to 15 | - | Detect to 8 | Risk Management Toolkit for Recreational Waters |
| CO | REC | Warning Value | - | >15 | - | EPA AWQC | - | EPA AWQC | - | >8 | Risk Management Toolkit for Recreational Waters |
| CT | DW | No Thresholds | - | - | - | - | - | - | - | - | |
| CT | REC | No Thresholds | - | - | - | - | - | - | - | - | |
| DE | DW | No Thresholds | - | - | - | - | - | - | - | - | |
| DE | REC | No Thresholds | - | - | - | - | - | - | - | - | |
| DC | DW | No Thresholds | - | - | - | - | - | - | - | - | |
| DC | REC | No Thresholds | - | - | - | - | - | - | - | - | |
| FL | DW | No Thresholds | - | - | - | - | - | - | - | - | |
| FL | REC | Health Notification Alert | - | Detect | - | Detect | - | Detect | - | Detect | Protecting Florida Together Water Quality Map |
| GA | DW | No Thresholds | - | - | - | - | - | - | - | - | |
| GA | REC | No Thresholds | - | - | - | - | - | - | - | - | |
| HI | DW | No Thresholds | - | - | - | - | - | - | - | - | |
| HI | REC | No Thresholds | - | - | - | - | - | - | - | - | |
| ID | DW | Single Tier Drinking Water Value | - | - | EPA HA | - | EPA HA | - | - | - | Cyanobacterial Blooms: Frequently Asked Questions |
| ID | REC | Single Tier Recreational Value | - | - | - | EPA AWQC | - | EPA AWQC | - | - | Idaho DEQ Cyanobacteria Harmful Algal Bloom Information |
| IL | DW | No Thresholds | - | - | - | - | - | - | - | - | |
| IL | REC | Single Tier Recreational Value | - | - | - | EPA AWQC | - | EPA AWQC | - | - | Illinois Environmental Protection Agency Harmful Algal Bloom (HAB) Dashboard |
| IN | DW | 303(d) Assessment Threshold | - | - | EPA HA | - | EPA HA | - | - | - | Indiana Reservoir and Lake Sampling Update |
| IN | REC | Advisory Value | - | 8 | - | 8 | - | 6 | - | 0.8 | Indiana Reservoir and Lake Sampling Update |
| IN | REC | Prohibited Value | - | 30 | - | 20 | - | 15 | - | 3 | Indiana Reservoir and Lake Sampling Update |
| IN | REC | Dog Recreation Advisory Value | - | - | - | 0.4 | - | 0.5 | - | - | Indiana Reservoir and Lake Sampling Update |
| IN | REC | Dog Recreation Prohibited Value | - | 0.4 | - | 0.8 | - | 1 | - | 0.05 | Indiana Reservoir and Lake Sampling Update |
| IA | DW | Single Tier Drinking Water Value | - | - | EPA HA | - | EPA HA | - | - | - | Drinking Water Health Advisories |
| IA | REC | Advisory Value | - | - | - | EPA AWQC | - | - | - | - | Beach Monitoring |
| KS | DW | No Thresholds | - | - | - | - | - | - | - | - | |
| KS | REC | Watch Level Value | - | - | - | >4 to <8 | - | - | - | - | KDHE Agency Response Plan – 2022 |
| KS | REC | Warning Level Value | - | - | - | >8 to <2000 | - | - | - | - | KDHE Agency Response Plan – 2022 |
| KS | REC | Hazard Level Value | - | - | - | >2000 | - | - | - | - | KDHE Agency Response Plan – 2022 |
| KY | DW | No Thresholds | - | - | - | - | - | - | - | - | |
| KY | REC | No Thresholds | - | - | - | - | - | - | - | - | |
| LA | DW | No Thresholds | - | - | - | - | - | - | - | - | |
| LA | REC | No Thresholds | - | - | - | - | - | - | - | - | |
| ME | DW | No Thresholds | - | - | - | - | - | - | - | - | |
| ME | REC | No Thresholds | - | - | - | - | - | - | - | - | |
| MD | DW | Single Tier Drinking Water Value | - | - | 1 | - | - | - | - | - | Harmful Algal Bloom Management in the Chesapeake and Coastal Bays |
| MD | REC | Single Tier Recreational Value | - | - | - | 10 | - | - | - | - | Harmful Algal Bloom Management in the Chesapeake and Coastal Bays |
| MA | DW | Single Tier Drinking Water Value | - | - | EPA HA | - | EPA HA | - | - | - | Cyanobacterial Harmful Algal Blooms (CyanoHABs) & Water |
| MA | REC | Single Tier Recreational Value | - | - | - | 14 | - | - | - | - | Cyanobacterial Harmful Algal Blooms (CyanoHABs) & Water |
| MI | DW | No Thresholds | - | - | - | - | - | - | - | - | |
| MI | REC | No Thresholds | - | - | - | - | - | - | - | - | |
| MN | DW | Single Tier Drinking Water Value | 0.1 | - | 0.1 | - | - | - | - | - | Human Health-Based Water Guidance Table |
| MN | REC | Single Tier Recreational Value | - | 7 | - | 6 | - | 15 | - | - | Harmful algae blooms: Water recreation advisories |
| MS | DW | No Thresholds | - | - | - | - | - | - | - | - | |
| MS | REC | No Thresholds | - | - | - | - | - | - | - | - | |
| MO | DW | No Thresholds | - | - | - | - | - | - | - | - | |
| MO | REC | No Thresholds | - | - | - | - | - | - | - | - | |
| MT | DW | Single Tier Drinking Water Value | - | - | EPA HA | - | EPA HA | - | - | - | Harmful Algal Bloom (HAB) Guidance Document for Montana |
| MT | REC | Tier 1 Caution Value | - | Non-detect | - | <4 | - | - | - | - | Harmful Algal Bloom (HAB) Guidance Document for Montana |
| MT | REC | Tier 2 Caution Value | - | Detect to 20 | - | 4-20 | - | - | - | - | Harmful Algal Bloom (HAB) Guidance Document for Montana |
| MT | REC | Tier 3 Consider Closure Value | - | >20 | - | >20 | - | - | - | - | Harmful Algal Bloom (HAB) Guidance Document for Montana |
| NE | DW | No Thresholds | - | - | - | - | - | - | - | - | Current Lakes on HAB* Health Alert |
| NE | REC | Health Alert | - | - | - | EPA AWQC | - | - | - | - | Current Lakes on HAB* Health Alert |
| NV | DW | No Thresholds | - | - | - | - | - | - | - | - | |
| NV | REC | No Thresholds | - | - | - | - | - | - | - | - | |
| NH | DW | No Thresholds | - | - | - | - | - | - | - | - | |
| NH | REC | No Thresholds | - | - | - | - | - | - | - | - | |
| NJ | DW | No Thresholds | - | - | - | - | - | - | - | - | |
| NJ | REC | Advisory Value | - | 15 | - | 2 | - | 5 | - | 0.6 | 2021 Cyanobacterial Harmful Algal Bloom (HAB) Freshwater Recreational Response Strategy |
| NJ | REC | Warning Value | - | - | - | >20 - < 2000 | - | - | - | - | 2021 Cyanobacterial Harmful Algal Bloom (HAB) Freshwater Recreational Response Strategy |
| NJ | REC | Danger Value | - | - | - | >2000 | - | - | - | - | 2021 Cyanobacterial Harmful Algal Bloom (HAB) Freshwater Recreational Response Strategy |
| NM | DW | No Thresholds | - | - | - | - | - | - | - | - | |
| NM | REC | Criteria | - | - | - | EPA AWQC | - | EPA AWQC | - | - | Water Quality Standards for Interstate and Intrastate Surface Waters |
| NY | DW | No Thresholds | - | - | - | - | - | - | - | ||
| NY | REC | No Bloom Value | - | - | - | <4 | - | - | - | - | Harmful Algal Blooms (HABS) Program Guide |
| NY | REC | Confirmed Bloom Value | - | - | - | 4 - 20 | - | - | - | - | Harmful Algal Blooms (HABS) Program Guide |
| NY | REC | Confirmed/High Toxins Shoreline Value | - | - | - | >20 | - | - | - | - | Harmful Algal Blooms (HABS) Program Guide |
| NY | REC | Confirmed/High Toxins Open Water Value | - | - | - | >10 | - | - | - | - | Harmful Algal Blooms (HABS) Program Guide |
| NC | DW | No Thresholds | - | - | - | - | - | - | - | - | |
| NC | REC | No Thresholds | - | - | - | - | - | - | - | - | |
| ND | DW | No Thresholds | - | - | - | - | - | - | - | - | Refer to Notes |
| ND | REC | Criteria | - | - | - | EPA AWQC | - | EPA AWQC | - | - | Water Quality Assessment Methodology for North Dakota’s Surface Waters |
| OH | DW | <6 yo value | 0.3 | - | EPA HA | - | EPA HA | - | 0.3 | - | Public Water System Harmful Algal Bloom Response Strategy |
| OH | DW | Adult value | 1.6 | - | EPA HA | - | EPA HA | - | 1.6 | - | Public Water System Harmful Algal Bloom Response Strategy |
| OH | REC | Single Tier Recreational Value | - | 8 | - | 8 | - | 15 | - | 0.8 | Harmful Algal Bloom Response Strategy for Recreational Waters |
| OK | DW | Single Tier Drinking Water Value | - | - | EPA HA | - | EPA HA | - | - | - | Public Water Supplies: Guidelines |
| OK | REC | Single Tier Recreational Value | - | - | - | - | - | - | - | - | |
| OR | DW | Oregon (vulnerable) | - | - | EPA HA | - | EPA HA | - | - | - | Cyanotoxin Monitoring and Public Notification at Public Drinking Water Systems |
| OR | DW | Oregon (all persons) | - | - | EPA HA | - | EPA HA | - | - | - | Cyanotoxin Monitoring and Public Notification at Public Drinking Water Systems |
| OR | REC | Single Tier Recreational Value | - | 15 | - | EPA AWQC | - | EPA AWQC | - | 8 | Cyanotoxin Monitoring and Public Notification at Public Drinking Water Systems |
| OR | DW | Dog Information Values | 0.4 | - | 0.2 | - | 0.4 | - | 0.02 | - | Advisory Guidelines Cyanobacteria Blooms in Recreational Waters |
| OR | REC | Dog Information Values | - | 0.4 | - | 0.2 | - | 0.4 | - | 0.02 | Advisory Guidelines Cyanobacteria Blooms in Recreational Waters |
| OR | LW | Single Tier Livestock Value | - | - | 2.3 | - | - | - | - | - | Methodology for Oregon’s 2022 Water Quality Report and List of Water Quality Limited Waters |
| PA | DW | Single Tier Drinking Water Value | - | - | EPA HA | - | EPA HA | - | - | - | What To Do if You Suspect a HAB |
| PA | REC | Recreation Advisory Value | - | >8 | - | EPA AWQC | - | EPA AWQC | - | >0.8 | What To Do if You Suspect a HAB |
| PA | REC | Avoid Primary Contact Value | - | >300 | - | >20 | - | >20 | - | >30 | What To Do if You Suspect a HAB |
| RI | DW | Do Not Drink Warning | 20-300 | - | 0.3-20 | - | 1-20 | - | 0.2-3 | - | Public Drinking Water (216-RICR-50-05-1) - Rhode Island Department of State |
| RI | DW | Do Not Use Warning | >300 | - | >20 | - | >20 | - | >3 | - | Public Drinking Water (216-RICR-50-05-1) - Rhode Island Department of State |
| RI | REC | Single Tier Recreational Value | - | - | - | 4 | - | - | - | - | Cyanobacteria Monitoring Program 2022 Report (Summer-Fall 2022) |
| SC | DW | No Thresholds | - | - | - | - | - | - | - | - | Harmful Algal Blooms |
| SC | REC | Criteria | - | - | - | EPA AWQC | - | EPA AWQC | - | - | Harmful Algal Blooms |
| SD | DW | No Thresholds | - | - | - | - | - | - | - | - | |
| SD | REC | Criteria | - | - | - | EPA AWQC | - | EPA AWQC | - | - | South Dakota Quality Assurance Project Plan for Monitoring for Harmful Algal Blooms |
| TN | DW | No Thresholds | - | - | - | - | - | - | - | - | |
| TN | REC | No Thresholds | - | - | - | - | - | - | - | - | |
| TX | DW | Single Tier Drinking Water Value | - | - | EPA HA | - | EPA HA | - | - | - | Guide for Public Health Response to Cyanobacterial Harmful Algae in Recreational Freshwater in Texas |
| TX | REC | Tier II Warning Advisory Value | - | Detected | - | 8 | - | 15 | - | - | Guide for Public Health Response to Cyanobacterial Harmful Algae in Recreational Freshwater in Texas |
| TX | REC | Tier III Danger Advisory Value | - | ≥60 | - | 20 | - | 17 | - | - | Guide for Public Health Response to Cyanobacterial Harmful Algae in Recreational Freshwater in Texas |
| UT | DW | Single Tier Drinking Water Value | - | - | EPA HA | - | EPA HA | - | - | - | Drinking Water FAQs: Harmful Algal Blooms |
| UT | REC | Warning Advisory Value | - | >15 | - | >8 | - | >15 | - | >8 | Utah Harmful Algal Bloom HAB Advisory Guidance |
| UT | REC | Danger Advisory Value | - | >90 | - | >2000 | - | - | - | >75 | Utah Harmful Algal Bloom HAB Advisory Guidance |
| VT | DW | Single Tier Drinking Water Value | 0.5 | - | 0.16 | - | 0.5 | - | - | - | Drinking Water and Groundwater Protection Division Template |
| VT | REC | Single Tier Recreational Value | - | 10 | - | 6 | - | 10 | - | - | Drinking Water and Groundwater Protection Division Template |
| VA | DW | Single Tier Drinking Water Value | - | - | EPA HA | - | EPA HA | - | - | - | Source Water Manual |
| VA | REC | Single Tier Recreational Value | - | 8 | - | EPA AWQC | - | EPA AWQC | - | 4 | Source Water Manual |
| WA | DW | Guidance Values - "Time to make a plan" | 0.3 | - | EPA HA | - | EPA HA | - | - | - | Guidance for Developing a Harmful Algal Bloom Management and Response Plan |
| WA | REC | Warning (Advisory) Value (Guidance) | - | 1 | - | EPA AWQC | - | EPA AWQC | - | 75 | Blue-Green Algae |
| WA | REC | Danger Value | - | >300 | - | >2000 | - | - | - | - | About Toxic Algae |
| WV | DW | Sensitive Value | 20 | - | EPA HA | - | EPA HA | - | 0.3 | - | Harmful Algal Bloom Drinking Water Response Plan |
| WV | DW | Adult Value | 20 | - | EPA HA | - | EPA HA | - | 1.6 | - | Harmful Algal Bloom Drinking Water Response Plan |
| WV | DW | Do Not Use Value | 300 | - | 20 | - | 20 | - | 3 | - | Harmful Algal Bloom Drinking Water Response Plan |
| WV | REC | Watch Value | - | >80 | - | >6 | - | >5 | - | >0.8 | What is a Harmful Algal Bloom (HAB)? |
| WV | REC | Warning Value | - | 300 | - | 20 | - | 20 | - | 3 | What is a Harmful Algal Bloom (HAB)? |
| WI | DW | Single Tier Drinking Water Value | - | - | - | - | - | - | - | - | |
| WI | REC | Single Tier Recreational Value | - | - | - | EPA AWQC | - | EPA AWQC | - | - | Blue-Green Algae |
| WY | DW | Single Tier Drinking Water Value | - | - | EPA HA | - | EPA HA | - | - | - | Region 8 DW Harmful Algal Bloom Response Actions |
| WY | REC | Toxin Advisory Value | - | 60 | - | EPA AWQC | - | EPA AWQC | - | 30 | Harmful Cyanobacterial Bloom (HCB) Action Plan for Publicly Accessible Waterbodies in Wyoming |
| Hoopa Valley Tribe | DW | Criteria | - | - | 1 | - | - | - | - | - | Water Quality Control Plan Hoopa Valley Indian Reservation |
| Hoopa Valley Tribe | REC | Criteria | - | - | - | EPA AWQC | - | - | - | - | Water Quality Control Plan Hoopa Valley Indian Reservation |
| Miccosukee Tribe | Bathing | Criteria | - | - | - | EPA AWQC | - | EPA AWQC | - | - | Miccosukee Tribe of Indians of Florida |
| Northern Cheyenne Tribe | Recreation | Criteria | - | - | - | EPA AWQC | - | EPA AWQC | - | - | Northern Cheyenne Tribe Surface Water Quality Standards |
| Pueblo of Sandia | Recreation | Criteria | - | - | - | EPA AWQC | - | EPA AWQC | - | - | Pueblo of Sandia Water Quality Standards |
| Santa Clara Pueblo | Recreation | Criteria | - | - | - | EPA AWQC | - | EPA AWQC | - | - | Santa Clara Pueblo Water Quality Code |
| Confederated Tribes of the Coos, Lower Umpqua, and Siuslaw Indians | Cultural and Ceremonial Uses Including Primary Contact and Human Health | Criteria | - | 15 | - | EPA AWQC | - | EPA AWQC | - | 8 | Confederated Tribes of the Coos, Lower Umpqua, and Siuslaw Indians Water Quality Standards |
| USEPA | DW | USEPA Health Advisories (< 6y) | - | - | 0.3 | - | 0.7 | - | - | - | EPA Drinking Water Health Advisories for Cyanotoxins |
| USEPA | DW | USEPA Health Advisories | - | - | 1.6 | - | 3 | - | - | - | EPA Drinking Water Health Advisories for Cyanotoxins |
| USEPA | REC | USEPA Recommended AWQC | - | - | - | 8 | - | 15 | - | - | 2019 Recreational Water Quality Criteria or Swimming Advisories for Cyanotoxins |
Abbreviations:
DW = Drinking Water
REC = Recreation
AWQC = Ambient Water Quality Criteria
HA = Health Advisory
LW = Livestock Watering