The City of Raleigh got some good new. As reported on WRAL, the Army Corps approved the City’s request to reallocate Falls lake’s storage toward drinking water allowing the City to increase the drinking water withdrawals by 22 million gallons a day. As we’ve covered previously, aside from drinking water, Falls Lake has several allocated uses that include flood control and sustaining ecological functions. With this change, lake managers will look to preserve more water in the lake to supply drinking water for Raleigh.
Why is this good news for the City? Raleigh has struggled to identify long-term water sources to provide for its growing population and even explored creating a new reservoir. With this move, Raleigh’s water supply is more secure for the foreseeable future. It also raises the importance of upstream watershed protection. If Raleigh is going to be counting more on Falls Lake, the City, State and region should be stepping up efforts to prevent its pollution and protect its long-term health.
A US Geological Survey Report released late in 2018 provides a needed review of water quality trends for select NC rivers and streams over the last 25-years (1989-2013). Importantly, the report focuses on the quality of water flowing to drinking water reservoirs in North Carolina. Here, I’ll briefly cover the results affecting Jordan Lake where data both in streams and the Lake were analyzed to gauge what’s happening and what’s needed to protect our drinking waters.
Over the 25-year study period, population in counties surrounding the Lake grew by 85%. Not surprisingly, during that period developed land use nearly doubled in watersheds draining to Jordan Lake, typically coming from less polluting forested land use. Also, during that time, improvements have been made to waste water treatment plants that have reduced the discharge of pollutants even though the plants were serving more users. Overall, there are a mixture of factors that have influenced water quality flowing to Jordan Lake.
What are the trends?
In a word, mixed. Generally, monitoring of nutrients in streams near Jordan Lake showed improvement TP concentrations more than TN (See Figure 1). Conditions in Jordan Lake, however, were less promising with stations showing increased concentrations for both TN and TP. Much like our estuaries, organic nitrogen was the primary form of N that increased during the period of study.
Increases in triangle-area population continue to put a strain on Jordan Lake both for adequate quantity and quality for its users. Even though management efforts over the study period resulted in some in-stream water quality improvement, conditions continue to be poor at the lake demonstrating the continued need for policies protective of the Lake.
The Chesapeake Bay has experienced problems similar to those in NC’s estuaries as it relates to nutrient pollution. Low-oxygen “dead zones’ have resulted in persistent fish kills and stressed or diminished aquatic ecosystems.
Area draining to the Bay stretches from from New York to Virginia and has had federally coordinated efforts to curb nutrient pollution since the 1980’s. These efforts combined with funding to improve wastewater treatment and improved development and agricultural practices have all played a role in improving water quality in the Chesapeake though not as much as bay managers would like.
The news this year is mixed.
Good News: In spite of a predicted larger than average dead zone “due to higher spring flows and nitrogen loading from the Susquehanna and Potomac rivers”, hypoxia (i.e. low oxygen) in the Bay for the month of July was historically good.
Bad News: Overall, summer hypoxia was average with late summer conditions worse than average.
What’s this mean? The challenge of reducing nutrient pollution and its associated water quality problems is formidable. As covered previously, sustained effort, political will, and funding are needed to make a positive impact. Even then, increased population, loss of wetlands and forest, and the misuse of nutrients can overwhelm these efforts, neutralizing progress. NC is in the process of re-adopting its nutrient rules. In doing so, it should look for opportunities to eliminate pollution loopholes and find ways to strengthen the overall effectiveness of its nutrient reduction strategies.
Hurricane Florence had numerous effects on North Carolina: Flooded neighborhoods, ruined crops, damaged infrastructure, and submerged businesses to name a few. All that water created what state officials were calling a 500 to 1000 year flood.
Indeed, floods put portions of the Lumber, Cape Fear, and Neuse at record or near-record flood levels. One of the negative effects of the storm was inundation of poultry houses, swine farms and hog waste lagoons located in the floodplain. The State estimated that waste from 50 lagoons washed out into the floodwaters and that 5,500 pigs and 3.4 million chickens drowned. While awful, many of these same facilities were flooded 2 years ago by Hurricane Matthew and/or 20 years ago by Hurricane Floyd.
How can the state better prepare for future storms? Twenty years ago, the state began a program to move hog facilities out of the floodplain. Reportedly, 43 high risk hog farms either moved or were closed in the years following Floyd. While a positive step, increased funding is needed to relocate the many remaining hog farms from the 500-year floodplain which seems to be the new norm for planning purposes.
After three 500 year storms in 20 years, planning for extreme events is something the state should undertake to minimize environmental impacts from future extreme weather events.
Source: NASA Earth Observatory
Following up on the previous post, managers of Falls and Jordan lakes are nearing the end of their lake draw down. For two weeks after Hurricane Florence made landfall, the flood storage usage of these lakes was in full effect as manages nearly eliminated water release from these dams. While that helped downstream communities from having additional upstream floodwaters piled onto already devastating floods, it also led to extremely high water levels at the lakes.
With the downstream floods abated, lake managers began drawing down the lakes’ levels September 25th. As demonstrated by Hurricane Florence, uses of these lakes goes well beyond drinking water and their conservation remains a high priority.
We touched on the uses of Jordan and Falls Lake in a previous post. One of those uses is currently evident in the aftermath of the recently passed Hurricane Florence. The storm dumped between 6 and 12 inches of rain over the Falls Lake Watershed. With those rainfall totals, discharge from the lake should be higher than normal or raging.
The flood storage use of the Lake’, however, requires that the Army Corps hold back water to help mitigate downstream flooding. With that objective you get the following hydrograph for Falls Lake where 62% of its storage is intended for flood control:
Lake managers will keep discharges from the Lake low to try to mitigate downstream flooding. They’ll hold the water behind the dam until the downstream flooding ebbs. Until that happens, however, you can walk across the Neuse below Falls Lake.
Hurricane Matthew’s impacted many North Carolina communities in 2016. One community, Zebulon, saw a historic dam on the Little River breached by the storm’s abundant rainfall. The breach has forced the town to reflect on the dam, its repair cost, and whether it should continue to stand along the river.
Repair, replace, or remove? Zebulon’s City Council has considered what to do with the dam voting not to repair. The costs for keeping the dam through repair are considerable. Vegetation has taken root in the mortared cracks throughout the structure compromising the dam’s integrity. Fixing the dam would mean removing the vegetation, replacing the mortar, and repairing the breached area with the town bearing much of the cost.
Sticking with their vote would be to allow the river to return to a more free flowing state. It would also allow use federal funding to make improvements to the park surrounding the Dam. This approach would also result in ecosystem benefits similar to the recent removal of the nearby Milburnie Dam on the Neuse River.
If the council sticks with their decision, there should be some positive improvement to both the Little River’s ecosystem and the town’s park.
Occasionally we use this blog to look outside our state at activities that may give insight to our State’s water resource management. For this post, I wanted to look at a bad situation occurring in Florida. There, sea birds, mammals, fish, and humans are suffering from a harmful algae bloom along the Gulf shores where a red tide originating in October 2017, has persisted and created a toxic environment for marine life and coastal residents.
A primary contributor to the bloom reportedly is legacy nutrients from Florida’s agricultural industry that were washed out of Lake Okeechobee by Hurricane Irma in 2017. The load of nutrients timed with seasonal red tide conditions to amplify an already bad situation.
The effects of the toxic algae have touched a broad array of marine fish. Goliath groupers, sea turtles, feeder fish are all washing up dead.
— Kelly Guthrie Raley (@kellyraley) July 30, 2018
Some of the conditions contributing to the bloom in Florida are present in North Carolina (previous blog posts). While the State has a number of nutrient reduction strategies in place, The State’s Environmental Management Commission is currently reviewing and revising those. North Carolina should be mindful of the threat of excess nutrients in their strategy update and curb nutrient laden runoff from our waterways.
In May 2018, water quality conditions at White Lake, located in Southeast NC, had deteriorated to the point where the Town of White Lake felt action was needed. Excessive nitrogen and phosphorus in the lake and warm spring temperatures had resulted in high algae levels turning its once clear waters to green. A video posted by Kyle McGee illustrates some of these conditions.
In response, the Town contracted for $500k with a company to kill algae on the lake through the use of alum (aluminum sulphate). Historically, White Lake’s waters are more acidic however it’s pH levels have been rising in recent years. The proposed treatment was to coat the lake with alum (aluminum sulphate) to kill the algae. A side effect of that treatment, however, was to
raise lower the lake’s pH.
In the end, the State believes that multiple factors including the preceding algae bloom, low dissolved oxygen, and effects of the alum treatment all contributed to the kill.
How bad was the resultant fish kill? A NC Wildlife Resource Commission report on the kill estimated that 115,000 fish encompassing 9 species died, many of which are tolerant of pollution. Overall the report estimated the value of the dead fish at over $600k.
Conditions contributing to the algal bloom are ones that we need to be mindful of at all our lakes. Over development eliminating natural buffers such as wetlands, septic leachate, and over fertilization of lawns can all contribute to algae blooms. Actions to reduce threats like these will be needed from the town and the State to prevent blooms from becoming a permanent problem for lake residents.
EDIT: Fixed some incorrect wording.