Expanding Areas of Eutrophication

Continuing the recap of the recent WRRI conference, Dr. Mike Mallin of my alma mater UNC-W presented his research titled “Onset of Unprecedented Toxic Cyanobacteria Blooms in the Cape Fear River”. In it, he highlighted troubling trends on the Cape Fear River.

First, nutrient levels have been steadily increasing since the mid-1990’s. Of the four stations he highlighted, ammonia trends had risen between 64% and 315% since 1995. While NC does not regulate ammonia levels, it does have standards for chlorophyll a (40μg/L) which can feed off nutrients like those in ammonia.  Since 2009, chlorophyll levels in the lower Cape Fear have been found to be exceeding that standard with one surface sample exceeding (1440 μg/L). Yikes!

Second, toxic algae levels were found to be high.  Toxic algae can cause rashes to exposed skin and, if ingested, disrupt the nervous system, or worse.  One Cape Fear reading for toxic algae had levels 75 times higher than the World Health Organizations standard of 1μg/L.  Double Yikes!!

Image courtesy of Dr. Mike Mallin.  Algal bloom in lower NC's Cape Fear River.
Image courtesy of Dr. Mike Mallin. Algal bloom in lower NC’s Cape Fear River.

Some of the concerns over these results are obvious: wildlife are threatened and human recreation in areas experiencing these blooms should be avoided.  Another serious concern is that Wilmington draws much of its water from the affected waters, contributing to increased water treatment costs and creating taste and odor problems in the City’s drinking water – a problem highlighted by Michael Richardson recently at NC’s forum on nutrient overenrichment.

The expansion and increased severity of nutrient related water quality problems in the state is presenting a challenge to the State regulatory agencies.  I’ll post more on this theme soon.





A few conference take-homes

This past week, NC’s Water Resources Research Institute held their annual meeting.  I dropped in for a session and talked with some presenters.  One theme presented in several talks is the continued and expanding problem of excess nutrients, or eutrophication, in area waters and the challenges that this presents.

Glenn Dunn touched on nutrient reductions efforts in the Neuse.  In the late 1990’s, NC passed a set of rules for this watershed to reduce its nitrogen levels by 30% from 1991-1995 levels.  In response, waste treatment plants upgraded their treatment technology.  Monitoring of their discharges  has shown decreases of over 60% on their annual nitrogen loadings.  Analysis of the estuary, however, does not show significant change to the estuary when flow is accounted for.  Why? Other sources of nitrogen are offseting their reductions.

Examined by Lebo, Paerl, and Peierls in research released in 2012, several forms of nitrogen are shown to be decreasing (see the graph below).  TKN, or organic nitrogen, however, has actually risen since the 1990’s when the estuary saw troubling algal blooms and fish kills.  Their analysis shows that the Neuse estuary and its ecosystems continue to be threatened by excess nutrient levels.

Flow-normalized N Loadings to the Neuse Estuary at Fort Barnwell, NC. (Source: Lebo et al., 2012)


I’ll post more soon on the expanding areas of the state facing eutrophication.


A Ride Along the Lil Muddy

Car problems pushed me onto the local greenway recently for a ride along Crabtree Creek.   After passing an initial worrisome sign that was intended to discourage me, it turned out nice to be on two wheels instead of four.

Backtrack or Go Around?
Backtrack or Go Around?

While nothing like the Big Muddy which drains much of our nation, the Creek was elevated from recent spring rains and running turbid.  Sources for the sediment include runoff from development in the watershed to the erosion of streambank sediments deposited in years and decades past that are being churned up by the fast flowing water.

Even with the dirty water, ‘Lil Muddy’ was a peaceful place to be.  The flowing waters made me forget the urban landscape and the birds were more of a chorus than the traffic.

Restoration for urban watersheds such as that for Crabtree Creek is complicated and expensive. Policies and resources are needed as well as participation of residents in the watershed.  A role for mitigation banks is to offer cost-effective options to reduce nutrients and improve the quality of water flowing down Crabtree Creek, to the Neuse River, and eventually to the Estuary.  While heavy flows will always dirty-up a river, through measures such as tree planting, erosion prevention and education efforts, we’re working to make it a lil less muddy.

High flows from spring runoff
Crabtree Creek under Capital Blvd.

Nutrients in NC

In North Carolina and other areas of the U.S., excess nutrients from fertilizers, agricultural and urban runoff, and industrial pollution have led to algal blooms, fish kills, and damaged ecosystems.  It can also increase water treatment costs and support the growth of toxic algae.

July 2012 algal bloom, Cape Fear River
Algal bloom, Cape Fear River (Source NC DWQ)

North Carolina has developed several strategies to better manage nutrients and keep them from leading to such problems.  Formal efforts from the state gained momentum in the late 1990’s with the passage of nutrient reduction strategies in the Neuse followed by the Tar-Pamlico

Basin.  Most recently, the State passed rules for improving the Jordan Lake (2009) and Falls Lake (2011).  The goal for these rules is to reduce nutrient runoff to help clean waters and reduce the nutrient related water quality problems (e.g., excess algae and fish kills).

Watershed Investments works to support these strategies through more cost-efficient options that help meet the State’s nutrient reduction requirements.  This is a challenge that the state needs to meet to have an environment we can enjoy now and into the future.

NC Watersheds with Nutrient Strategies

NC’s Nutrient Strategy Watersheds


Nutrients – Too much of a good thing

We use fertilizer to grow food and keep our lawns green.  While it has helped our food production keep pace with the world’s growing populatFertilizerConsumptionion, it has led to challenges when it comes to managing our water resources.

What’s the problem?  While we need the fertilizer to help produce food to feed the world’s growing population, it’s use leads to increases in nutrient runoff to our waters.  This isn’t just a North Carolina problem, its a worldwide one.

North Carolina researcher Dr. Hans Paerl sent back these photos from some his work in Taihu, China where nutrient runoff is contributing to excessive algal growth in lakes.

Though not North Carolina, these photos illustrate the problem of excessive nutrients, or eutrophication.  Eutrophic waters lead to algal blooms, fish kills, and damaged ecosystems.  It can also increase water treatment costs and support the growth of toxic algae.  Altogether, something that we at Watershed Investments are working to avoid.

Algal bloom Taihu, China
Source: Dr. Hans Paerl
Algal bloom, Taihu China
Water Skiing Anyone?