The Benjamin Harrison Bridge over the lower James, where large algal blooms have been detected this fall. (Spencer Tassone/Virginia Commonwealth University)

The fall foliage may be dull, but parts of the James River are slightly brighter this October thanks to the “flash drought” that has gripped much of the Southeast for the past month.

East of Hopewell, the largest blooms of algae detected in the James in several years are spreading as a lack of precipitation and higher-than-normal temperatures combine to produce ideal conditions for the organisms.

“Typically the biggest blooms are in July and August,” said Paul Bukaveckas, an ecologist with Virginia Commonwealth University. “Whereas here we saw the bloom expanding through September and continuing to grow.”

That pattern is out of the ordinary for a region where September usually ushers in cooler temperatures and several inches of rain. But it may become more common as climate change drives temperatures upward and makes weather more erratic.

“Higher temperatures and less consistent precipitation patterns driven by climate change are making extreme weather like droughts more prevalent around the world, and Virginia is no exception,” Secretary of Natural Resources Matthew J. Strickler said in a drought watch advisory issued by Gov. Ralph Northam on Oct. 11.

The Evidence for Climate Change

There is overwhelming consensus among scientists that the Earth’s climate is warming, and that this warming is largely driven by human action. Although regions have always experienced natural temperature fluctuations, long-term temperature records show an “unequivocal” warming trend since the 1950s. Other measurable changes such as accelerated melting of glaciers and ice sheets, sea level rise and increasingly extreme weather provide further clear evidence that warming is occurring. According to the United Nations Intergovernmental Panel on Climate Change, which draws on research by thousands of scientists worldwide, this warming is “extremely likely” (defined as greater than 95% probability) to have been caused by human actions, particularly the release of “unprecedented” levels of greenhouse gases into the atmosphere since the mid-20th century. The U.S. Fourth National Climate Assessment released by the Trump administration in November 2018 similarly found that “observational evidence does not support any credible natural explanations for this amount of warming.”

Sources: IPCC, Climate Change 2014: Synthesis Report; NASA, “Climate Change: How Do We Know?”; U.S. Fourth National Climate Assessment.

Algal blooms occur when bodies of water have an overabundance of nutrients, usually nitrogen and phosphorus, which flow from wastewater treatment plants, agricultural fields or city streets. The lower James is particularly prone to such blooms, said Bukaveckas, both because of its shallowness, which lets more light into the water column, encouraging algal growth, and because of the high number of wastewater facilities that line its banks.

Large blooms were last detected in the James in 2015 and 2010, although the kind of algae that flourishes in the river and the regular mixing of waters produced by tides sweeping into its lower regions from the Chesapeake Bay mean that the public doesn’t often notice when these events occur.

“A lot of what we’re seeing in the James is dispersed,” said Jamie Brunkow, the James Riverkeeper and an advocacy manager with the James River Association. “It’s not the dramatic view that we’ve seen in Lake Erie in recent years. … However, that doesn’t mean there isn’t a really high concentration of algae.”

Blooms aren’t just unsightly. Environmentally, they’re bad for water quality, choking out other plants and jeopardizing the fish and other aquatic organisms that rely on them. And they can be accompanied by blooms of toxic cyanobacteria, often called “blue-green algae,” which can harm human and animal health. (Along with monitoring the algae’s spread, VCU is conducting toxicity tests to determine whether the bloom poses any health risks, but Bukaveckas said that results won’t be available for several weeks.)

‘A system that is out of balance’

This year, the root cause of the algae explosion is clear: drought. With Virginia facing its driest autumn in a decade, less rainfall and unusually high temperatures have meant not only that less freshwater has entered the river, but also that water flows have slowed and the already shallow tidal James has become even shallower.

That in turn has ensured that nutrients stay in one place for longer, and that more light reaches algae organisms. The equation is simple: More food plus more fuel equals more algae.

“Under favorable conditions, they’re capable of growing very quickly,” said Bukaveckas.

water samples
Water samples from the lower James, Mattaponi and Pamunkey rivers drawn by Virginia Commonwealth University researchers. The James River sample is “quite green” compared to the other two, noted ecologist Paul Bukaveckas. (Paul Bukaveckas/VCU)

Droughts can’t be stopped, but Virginia has taken steps to reduce the likelihood of algal blooms, particularly through its revision of the standards that govern how much chlorophyll can be present in the James. Chlorophyll, the chemical that allows plants to transform light into fuel for growth through the process of photosynthesis, is an indicator of the amount of algae in a body of water. High concentrations of chlorophyll indicate large quantities of algae — which in turn indicate an overabundance of nutrients.

To reduce these chlorophyll levels, policymakers have particularly looked to wastewater treatment plants. Those in the James River basin have been special targets, for a simple reason: according to the Secretariat of Natural Resources, they account for 80 percent of the state’s point-source pollution, the term used to describe pollution that flows from a single location (compared to, say, a large network of urban storm drains or agricultural land).

That focus has produced what Chesapeake Bay Foundation scientist Joe Wood called “massive nutrient reductions” from Richmond, as well as other locations along the lower James. Since 2009, upgrades to facilities throughout the river basin have cut nitrogen and phosphorus pollution by about half.

The drops are impressive, but to Brunkow, the algal blooms are proof that the reductions haven’t been enough: “The river is still a system that’s out of balance,” he said.

Officials seem to agree. Under its most recent plan to meet Chesapeake Bay water quality goals by 2025, Virginia is calling for further reductions in pollution from wastewater treatment plants, which Wood said would have clear benefits for the health of the lower James. And this past June, the State Water Control Board approved new chlorophyll standards for the tidal portion of the river that are more closely tailored to the waterway’s unique conditions and are overall more stringent than they previously had been.

What may throw a wrench into all of this progress is climate change.

“Years like 2019 where we have record rain the previous year (and go) right into record drought conditions… could be an indication of the climate that’s coming,” said Brunkow.

State environmental officials are conscious of the need to take climate change into account when grappling with water quality problems like algal blooms. The most recent bay cleanup plan explicitly predicts that greater pollution reductions will be necessary “to offset the effects of climate change by 2025.” Among other sources, those increased pollution loads will likely be due to an overall trend of increasing precipitation and sea level rise that may cause greater erosion and runoff.

When it comes to algal blooms, those considerations are equally applicable, said Brunkow.

“We should be considering our likelihood of meeting the chlorophyll standards in light of climate change and the swinging conditions” that characterize it, he said.