Written by Bria Metzger '20
Edited by Elana Balch '21.5
In the heat of the summer of 2015, vast tracts of the Wallkill River in New York turned green for the first time — but not the last. It happened again in 2016. The green took on the appearance of mats, foam, scum, and even, in a few desperate calls to local environmental groups, spilled buckets of green paint .
These thick green swaths may look like algae, but the offending organisms are actually cyanobacteria, somewhat misleadingly called ‘blue-green algae’. Like algae, cyanobacteria are photosynthetic: they store the sunlight they receive as nutritionally-packed sugars. Like other photosynthetic organisms, they’re limited by nitrogen and phosphorus, the two main components of any fertilizer. When the weather is right and resources are abundant, they’re well-equipped to take advantage. A HAB can quickly cover an entire lake, or, in the case of the Wallkill, 30 miles of river .
Unlike algae, however, these cyanobacteria produce secondary metabolites that are toxic to humans and wildlife. For humans, contact with the water results in a stinging nettle-like skin rash, and swallowing the water can result in severe liver and nerve damage. Several dogs have died after playing in affected water bodies; the record of dog mortality due to encounters with toxic blooms stretches all the way back to the 1920s .
HABs are increasing in frequency, severity, and range of waters affected. Reservoirs and lakes are especially susceptible given that these blooms typically require slow, still water. The Wallkill River was regarded as too fast-flowing to sustain any significant blooms, right up until the first summer it turned bright green. So what’s changing?
One proximal cause: increased phosphorus and nitrogen runoff. Changes in climate, land use, and agricultural and gardening practices have all contributed to this increase. Summers in the Northeast are increasingly typified by brief but intense storms followed by long days of sunny calm. The sudden influx of water after each storm results in massive volumes of runoff. Cascading through nearby towns, the runoff runs over impermeable surfaces like pavement, roofing, and concrete; instead of soaking into the soil, it gains momentum, collecting fertilizer from lawns and farms on its downhill trip to the lake. Once in the water, the same nitrogen and phosphorus that nourish lush gardens and productive fields also nourish prolific harmful algal blooms .
Dan Shapely, water quality program director for the organization Riverkeeper, mentioned in an interview that monitoring techniques had revealed two point sources of nitrogen pollution for the Wallkill River: a failing pump station and an outdated sewage treatment plant, both upstream of the worst of the bloom . But identifying and correcting point sources of nutrient pollution will only help a fraction of HAB-prone waters. In the case of the Wallkill, the biological balance was tipped by poor infrastructure or overdue repairs. In most cases, however, the causes of HABs are harder to pinpoint and far more challenging to remedy.
More holistic solutions involve structural changes to communities within the affected watersheds. Beyond up-to-date waste- and storm-water management systems, communities can also develop green infrastructure. Rain barrels, rain gardens, and reconstructed wetlands all can slow and filter runoff . Planted riparian buffers, consisting of bands of trees that bound both sides of a river, are another well-supported means of keeping waterways clean. Their root systems gird the bank to reduce erosion and slow the rapid flow of runoff, allowing the polluted water to soak in and undergo a degree of biological remediation. A 2014 study from the Stroud Center found that a forested buffer can keep an average of 43% of sediments and 27% of nutrients, including nitrogen, from entering a stream [7,8].
Of course, these long-term, large-scale solutions require funding. In New Jersey, Republicans are drumming up resistance to a proposal they call the “rain tax”: a tax that would charge properties, residential and commercial, based on the amount of stormwater they generate. Given that residential lots are smaller and generally have more porous, earthen space compared to the vast tracts of impermeable concrete and blacktop of commercial lots, the impact on households would be minimal. The money generated would go to fitting the affected communities with sewage infrastructure. Most states — more than 40 — have storm water utilities that collect and filter runoff from storms . In New Jersey, by contrast, polluted runoff flows directly into streams, rivers, and bay . Many of the state’s oldest cities rely on outdated infrastructure that funnels stormwater and sewage into the same system .
Considering the multitude of factors that contribute to each bloom, it becomes clear that reducing the frequency and severity of HABs will take more than fixing faulty pumps and revamping treatment plants. A systemic problem requires systemic change.
As opponents of these measures and the means to finance them are quick to point out, HABs are not new occurrences. They have a long history as biological phenomena that cycle with the weather — but this history is ongoing and shifting rapidly in new ways that threaten the health of our wildlife, communities, and recreation-based economies. A long history is not an excuse to dismiss these blooms as potential warning signs or calls to revise our practices.
 Riverkeeper. Confirmed: Wallkill River Algae Produced High Toxin Levels [Internet] [10/16/19]. Available from: https://www.riverkeeper.org/news-events/news/water-quality/confirmed-wallkill-river-algae-produced-high-toxin-levels/
 Gilson, R.H. Don’t Swim in the Wallkill River [Internet] [10/16/19]. Available from: URL
 National Center for Environmental Health, Centers for Disease Control and Prevention; presented by Backer, L.C. Harmful Cyanobacteria and Algae Blooms: Human Dimensions. [Internet]. 3/16 [10/16/19]. Available from: URL https://www.epa.gov/sites/production/files/2016-03/documents/harmful-cyano-human-dimensions.pdf
 Howarth, B. The HABs – Nutrient Connection: Might Nitrogen Play a Role? [Internet]. 3/9/2019 [10/16/19]. Available from: https://s3.amazonaws.com/assets.cce.cornell.edu/attachments/37549/Howarth_Nitrogen_and_HABs_03092019.pdf?1556202817
 Dunne, A. Wallkill River Summit: NYS DEC To Begin Clean Water Plan. [Internet]. 5/16/19 [10/16/19]. Available from: https://www.wamc.org/post/wallkill-river-summit-nys-dec-begin-clean-water-plan
 West, J. Poison Waters: Toxic Algae in the Wallkill River [Internet] [10/16/19]. Available from: https://www.bard.edu/cep/blog/?p=9292
 The Stroud Center. Scientists Set Buffer Width Minimum Standard [Internet] [10/16/19]. Available from: https://stroudcenter.org/news/how-many-trees/
 Sweeney, B.W., and Newbold, J.D. Streamside forest buffer width needed to protect stream water quality, habitat, and organisms: a literature review. Publication [Internet]. 2014 [10/16/19]; 50(3), 560-584. DOi: doi:10.1111/jawr.12203
 Warren, M.S. It’s called a ‘rain tax.’ But will it really it help N.J. fight floods and stop pollution? [Internet] [10/16/19]. Available from: https://www.nj.com/news/2019/02/some-call-it-a-rain-tax-but-it-could-help-nj-fight-floods-and-stop-pollution.html
 Elizabeth, N.J. ‘Rain Tax’ Likely To Become Reality In New Jersey [Internet] [10/16/19]. Available from: https://newyork.cbslocal.com/2019/02/04/rain-tax-likely-to-become-reality-in-new-jersey/
 Warren, M.S. The controversial ’rain tax’ bill designed for N.J. flood defense has been signed into law [Internet] [10/16/19]. Available from: https://www.nj.com/news/2019/03/the-controversial-rain-tax-bill-designed-for-nj-flood-defense-has-been-signed-into-law.html