Montana water health

Live list of Montana beaches under advisory or closure for E. coli, sewage, or algal blooms. State Beach Monitoring Program data updated daily.

Under the federal BEACH Act, states test coastal and Great Lakes beaches for E. coli and enterococci during swim season (May–September in most states). A beach typically goes under advisory when E. coli exceeds 235 colonies per 100mL or enterococci exceeds 70 — the EPA thresholds linked to a ~3.6% risk of gastrointestinal illness from swimming. A closure means contamination is severe enough that the beach is closed to the public.

• Before swimming, check your state health or environmental agency's daily beach advisory list.
• Avoid swallowing lake or ocean water — most bacterial risk is from accidental ingestion.
• Don't swim within 24-48 hours of heavy rain (storm runoff carries the most contamination).
• If you swim at an advisory beach and feel sick within 5 days, call your county health department.

Active boil-water advisories, lead-action exceedances, and EPA Safe Drinking Water Act violations for Montana public water systems.

The U.S. has ~150,000 public water systems regulated under the federal Safe Drinking Water Act, which covers lead, copper, bacteria, nitrate, arsenic, PFAS, and disinfection by-products. Each state runs its own SDWA primacy program that handles violations, boil-water notices, and lead-action exceedances. EPA SDWIS aggregates the data.

• During a Boil Water Advisory: boil water 1 full minute before drinking, cooking, ice, or brushing teeth.
• For lead concerns: run cold water 30 seconds before drinking if a faucet has been unused for several hours.
• Get your annual Consumer Confidence Report from your water utility every July.
• For wells: test annually for bacteria and nitrate, every 3 years for arsenic, every 5 years for radon.

NOAA Great Lakes Harmful Algal Bloom Outlook for Lake Erie, Saginaw Bay, and other Montana waters. Bloom severity, location, and drinking-water risk.

Harmful algal blooms (HABs) are excessive growths of cyanobacteria (blue-green algae in freshwater) or other algae (red tide, brown tide along coasts) that can produce toxins like microcystin, brevetoxin, or domoic acid. Blooms can poison drinking water, kill fish, and cause respiratory irritation for people on shorelines. The 2014 Toledo water crisis — microcystin contamination of drinking water for ~500,000 people — was caused by a cyanobacteria bloom in western Lake Erie.

• Do not swim, drink, or let pets enter water that looks like spilled paint, has green or red scum, or smells musty.
• If exposed, rinse skin and eyes with clean water immediately. Watch for nausea, vomiting, or skin rash.
• If your drinking water comes from a surface water source (lake, reservoir, river), check your water utility's daily advisories during bloom season.
• Report a suspected bloom to your state environmental agency (EPA / DEQ / DNR) with photos and GPS location.

Census-tract environmental health and chronic disease burden across Montana from CDC PLACES. Asthma, COPD, cancer, cardiovascular, and air-quality impact.

CDC PLACES is the first national project to map chronic disease rates, health behaviors, and prevention measures at the census-tract level. It shows where asthma, COPD, cancer, diabetes, and cardiovascular disease are concentrated — often overlapping with industrial corridors, freeway-adjacent neighborhoods, and historic redlining areas.

• Find your census tract's health profile at https://www.cdc.gov/places/
• If you live in a high-asthma area, ask your doctor about an asthma action plan; many states fund home-visit programs through their Medicaid agency.
• EPA EJScreen maps cumulative environmental risk on top of this data: https://www.epa.gov/ejscreen
• For indoor air-quality help, your county or city health department may offer free home assessments — check their website.