Harmful Algal Blooms and Drinking Water in Oregon

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Harmful algal blooms are a major environmental problem in all 50 states.

Overview

Harmful algal blooms affect aquatic ecosystems, endangered species, and drinking water supplies. They are increasingly a public health hazard, and future climate conditions are expected to produce even more favorable conditions for the growth of cyanobacteria, leading to earlier, more frequent, and larger algal blooms.

Over the past decade, various cyanotoxins including microcystins, anatoxin-a, and cylindrospermopsin have been detected in the surface waters of rivers around Oregon, including the Clackamas, North Santiam, and Tualatin River systems, which are important drinking water sources for a substantial number of Oregon’s residents. Harmful blooms have resulted in numerous water contact and recreational closures and health advisories in lakes, reservoirs, and rivers; dog deaths have been associated with exposure to cyanotoxins. Cyanobacterial blooms produce a range of materials (geosmin, organic matter, toxins) that are a threat to the quality of drinking water supplies, and impose an increased burden on drinking water providers for monitoring and treatment. These issues are harder to address in a timely and effective manner when the sources and nature of the threats are not entirely known.

algal bloom

Algal bloom in the Ross Island Lagoon, Willamette River, Oregon (Photo: Kurt Carptenter, USGS).

 

Cyanobacteria and Harmful Blooms (CyanoHABs)
Cyanobacteria are a ubiquitous and vital part of Earth's ecosystem, producing atmospheric oxygen through their photosynthesis for billions of years. Today, cyanobacteria continue to share vast amounts of oxygen from their photosynthesis in the ocean and are an important part of many aquatic food webs. They may “fix” atmospheric nitrogen that enhances crop yields and agricultural production. But under certain conditions, when nutrients, light, and proper habitat converge, cyanobacteria often grow into noxious and toxic harmful blooms (CyanoHABs) that threaten water quality, drinking water, endangered species and other aquatic life, and human health.

CyanoHABs occur in many different types of waterbodies, including drinking water reservoirs, lakes, and other ponded waters. In these environments, cyanobacteria outcompete other algae when the surface warms and the waterbody temperature stratifies. Under these conditions many types of algae sink into the dark depths, whereas the more "buoyant" cyanobacteria (which are rich with gas vesicles) remain higher in the water column, closer to the sun.

Blooms of cyanobacteria may also occur in rivers, both as suspended “seston” in large flowing rivers, as well as extensive growths along riverbeds and channel margins. The basal forms of cyanobacteria form slimy filamentous mats (Microcoelus, Oscillatoria, Phormidium), and globular or “ear” shaped rubbery colonies of Nostoc, which are found on rocks, logs, and freshly exposed faces of basalt. These growths are observed in the rivers draining the Western Cascades that are vital to Oregon’s population for providing municipal drinking water.

While not all cyanobacteria blooms are toxic, they may produce an array of compounds including potent liver toxins (hepatotoxins, such as microcystins and cylindrospermopsins) and neurotoxins (anatoxin-a and saxitoxin, for example) that are especially dangerous to dogs, and even large animals including sheep, mountain goats, and cattle. Cyanobacteria also produce lipopolysaccharides that are skin irritants and may pose other concerns for water contact recreationists. Cyanobacteria also produce compounds that can foul water supplies with unpleasant tastes and odors. CyanoHABs are increasingly a public health hazard, with increased efforts to combat CyanoHABs at the federal and state levels, including Oregon, California, and Washington.

 

lake profiler

Lake profiler deployed on Detroit Lake, Oregon, to study harmful algal blooms in the reservoir (Photo: David Weathers, USGS).

CyanoHABs in Oregon
In 2018, detection of cyanotoxins (microcystins and cylindrospermopsins) in treated drinking water led to the first drinking water advisory of its kind in Oregon, restricting water consumption for the young, elderly, and sensitive population. In Oregon, HABs have potential to impact revenue from recreation, with numerous popular waterbodies having multiple advisories over the past decade due to HABs and the toxins they produce, including Detroit Lake, Timothy Lake, Tenmile Lake, Odell Lake, Upper Klamath Lake, and many others. CyanoHABs are not limited to one or two types of waterbodies; blooms of Dolichospermum (formerly Anabaeana) are common in the large water storage reservoirs on the Willamette’s tributaries, and in several lakes in Lincoln and Clatsop Counties along the coast (Cullaby, Carnihan, Ten Mile, and Devils’s Lake, for example) where Gloeotrichia, Aphanizomenon, Microcystis, and other cyanobacteria can bloom during summer months. CyanoHABs in small agricultural (nursery) irrigation ponds have also led to releases of cyanotoxins downstream and on to drinking water intakes. And in central Oregon, out on the range, various stock ponds and reservoirs used for cattle watering have experienced CyanoHABs with resulting deaths of cattle  with 32 cattle perishing near Lakeview in once incident in 2017. 

USGS studies of some of Oregon’s critical drinking water sources reveals the presence of cyanotoxins including microcystins, anatoxin-a, saxitoxin, and cylindrospermopsin in the surface waters of the Clackamas, North Santiam, McKenzie, and Tualatin River systems, which are important drinking water sources for hundreds of thousands of Oregon residents.

After the 2018 drinking water crisis for the State capital of Salem due to a CyanoHAB in Detroit Lake, USGS partnered with Salem, the U.S. Army Corp of Engineers, and the City of Eugene, Oregon, to more closely monitor CyanoHABs in Detroit Lake and nearby Cougar Reservoir in the McKenzie River Basin.
 

Active Research in Oregon

Harmful algal blooms impact aquatic ecosystems, endangered species, and drinking water supplies.

Over the past decade, various harmful blooms have resulted in numerous water contact and recreational closures and health advisories in lakes, reservoirs, and rivers; dog deaths have been associated with exposure to cyanotoxins. Cyanobacterial blooms produce a range of materials (geosmin, organic matter, toxins) that are a threat to the quality of drinking water supplies, and impose an increased burden on drinking water providers for monitoring and treatment. These issues are harder to address in a timely and effective manner when the sources and nature of the threats are not entirely known.

There are several CyanoHAB interpretive projects and monitoring programs underway:

  1. Benthic cyanobacteria occurrence and cyanotoxin production in three Cascade Range Rivers used for municipal supply: Clackamas, North Santiam, and McKenzie Rivers. Study includes deployment of Solid Phase Adsorption Toxin Trackers (SPATTs) at several drinking water intakes, and assessment of cyanobacteria colonies on river substrates and in the river plankton.
  2. Enhanced monitoring of the North Santiam and McKenzie Rivers, includes continuous, real-time monitoring of HAB parameters (water temperature, pH, dissolved oxygen, total chlorophyll, phycocyanin, and fDOM) in two reservoirs—Detroit Lake and Cougar Reservoir—with downstream continuous monitors providing real time data as an early warning system to downstream drinking water providers.
  3. Deployment of SPATTs in New York’s Finger Lakes region. Collaboration with the USGS NY WSC includes deployments in three lakes and three depths per lake, during the summer and early autumn growing season.
  4. Deployment of SPATTs in CA’s Rodeo Lagoon, where blooms of Nodularia contribute to poor water quality, and production of nodularin cyanotoxin, that causes low dissolved oxygen and other water quality issues for aquatic life, including the ESA-listed Gobi fish, which experience periodic fish kills during episodes of degraded water quality.
  5. Periodic monitoring of cyanobacteria in Portland’s Ross Island Lagoon, which experiences blooms of Dolichospermum, Aphanizomenon, and Microcystis, which can produce toxins exceeding Oregon Health Authority guidelines leading to water contact recreational advisories during summer.

 

algae

Cyanobacterium Gloeotrichia echinulata under a microscope (Photo: Barry Rosen, USGS).

USGS Laboratory Capabilities

The USGS Oregon Water Science Center has researched and implemented methods for the evaluation of cyanotoxins in water and in the cyanobacteria colonies on rock substrates and in river and lake/reservoir plankton. These included the use of passive samplers (Solid Phase Adsorption Toxin Trackers, or SPATTs), which concentrate cyanotoxins from the water column over time; these can be extracted and analyzed using Enzyme Linked Immunosorbent Assays (ELISA). Cyanotoxins currently analyzed at the USGS include total microcystins/nodularin (ADDA), cylindrospermopsin, saxitoxin, and anatoxin-a. Chlorophyll-a is also measured in the laboratory as an estimate of the total algal biomass in water, benthic, and plankton net tows.

 

Additional Resources

Oregon Health Authority

U.S. Environmental Protection Agency

grass

Stargrass in the Yakima River, Oregon (Photo: Kurt Carptenter, USGS).