Lake Norman, Mountain Island Lake, and Lake Wylie cover more than 47,000 acres. Together, the three lakes bordering Mecklenburg County hold about 465 trillion gallons of water. The water quality of the three lakes meets state standards for the lakes' intended uses. The NC Division of Water Quality has classified the lakes as
Class B and WS-IV waters for use by residents, industry and supplying drinking water. The lakes provide approximately 110 million gallons of drinking water each day to Mecklenburg County residents.
Based on the Lake Use-Support Index (LUSI) developed by Storm Water Services, the overall water quality downstream of Mecklenburg County at
Lake Wylie is very good; it improves upstream at
Mountain Island Lake, and improves still further upstream at
Lake Norman. The LUSI data presented in the links includes data from all of our lake monitoring sites including several main channel sites.
LUSI is based on various water quality parameters. Each parameter is an independent measure of water quality, with fecal coliform being the most important
indicator of swimmability. Fecal coliform bacteria levels are usually low in the three lakes, except in coves after significant storm events. Bacteria levels that exceed North Carolina water quality standards can directly impact the health of swimmers.
The bioaccumulation of toxins in fish tissue due to prolonged exposure to pollutants has resulted in the issuance of advisories by the State on the number of fish that are safe for human consumption. More about
fish consumption advisories on local lakes.
For more information contact:
Streams are classified by the NC Division of Water Quality for a variety of beneficial uses. In Mecklenburg County, all streams have been classified as Class C. That means the water is to be protected for "secondary recreational uses" with occasional human contact such as fishing and wading. To assess stream health, Storm Water Services calculates the Stream Use Support Index (SUSI).
The Greatest Negative Impact
The discharge of untreated, undetained runoff from impervious surfaces has the greatest negative impact to surface water quality. In 2007 and 2008, the City of Charlotte, Mecklenburg County and the Towns adopted ordinances to address these impacts. These ordinances apply to new development and redevelopment but do not apply to existing development. The jurisdictions are actively involved in restoration efforts to address water quality impairment from existing development through the use of storm water fees and grant funds.
More than 300 major stream miles are monitored for more than a dozen parameters at least monthly by Storm Water Services. Each parameter is an independent measure of water quality and the monitoring results are combined to calculate the SUSI.
Fecal Coliform Bacteria levels are among the parameters monitored to determine compliance with Class C criteria. Lower levels of fecal coliform result in a higher percentage of stream miles suitable for human contact. Bacteria levels are usually lower during base flow conditions but increase significantly during and after heavy rainfall. Sources of fecal coliform include sanitary sewer overflows and waste from wildlife, pets and farm animals.
Additionally, 24-hour in-stream monitoring occurs through the Continuous Monitoring and Alert Notification Network (CMANN). Pollution sources are often identified through stream walks, citizen complaints, industrial inspections and various other activities.
For more information contact: Rusty.Rozzelle@mecklenburgcountync.gov
Groundwater is a vital, natural resource in Mecklenburg County with 15% of its residents depending on it daily for their water supply. In addition, there is an increasing demand for groundwater use for irrigation and industrial processes. It is also important to mention that groundwater serves as the base flow for most of the county's streams.
Data collected from well construction records indicate yield rates to be highly variable, ranging from zero (a dry well) to 100 plus gallons per minute. Currently, there are no federal, state or local regulations that mandate wells to have a minimum yield. The average yield of a new well in Mecklenburg County is 24 gallons per minute, however, 65% of the new wells drilled yield 15 gallons per minute or less. Since 2014 there has been a drop in the average yield of new wells by six (6) gallons per minute. There has also been an increase (18%) of new wells with a yield of 15 gallons per minute or less. There is no data available to explain the reason(s) for the overall drop in yield, however there are many variables that may play a role in the decrease. Some of these variables would be: the density of water supply wells in a given area, the depth of the well, the accuracy of how the yield rate is measured and reported and topographically where the well is drilled.
The recharge of the groundwater system is directly dependent on the amount of precipitation received in a given area and how that precipitation is managed. Mecklenburg County receives on average of 42 inches of rainfall annually, but how much of that precipitation is allowed to percolate down through the soil and into our unconfined bedrock aquifer? In an urban area where there is an increased amount of impervious surfaces, rainwater flows quickly off streets and parking lots, through the storm drainage system and directly into the streams. Groundwater recharge can only occur in vegetated, natural areas such as parks, recreational fields and nature preserves, where large amounts of rain water can be absorbed slowly into the ground.
The current rate of groundwater usage in Mecklenburg County is sustainable. The quality of our groundwater in most areas is good and requires little or no treatment prior to use. There are areas in the county where the groundwater has been contaminated and therefore should not be used for any purpose.
There are more than 1,560 known soil or groundwater contamination sites in Mecklenburg County that have been documented and mapped. Since 2014 there have been 160 new contamination sites added to the Mecklenburg Priority List (MPL). Field investigations of the water supply usage around these sites have identified 271 contaminated wells of which, nine (9) have been added since 2014.
Local regulations put in place since 2005 prevent new wells from being constructed within 1,000 feet of a known contamination site. The exception to this would be if there was no other source of potable water available to serve a residence. In order to protect the water supply, wells constructed within 1500' of a documented contamination site are required to have additional construction and sampling requirements.
Groundwater protection is important for public health and the health of our stream ecosystems. Well permitting procedures put in place since 2005 have ensured that newly constructed water supply wells meet appropriate set backs away from potential sources of contamination. To ensure safe drinking water for residents, new wells are sampled for bacteria and a variety of inorganic chemicals. Educating well owners about well head protection is critical to protecting our groundwater resources for years to come.
Poorly Maintained Wells: Water supply wells serve as direct conduits to the natural aquifer. Unfortunately, when an old well or low producing well falls into disrepair it provides a direct path for contaminants to enter the groundwater (aquifer) system. Permanent well abandonment requires a permit (at no cost to the customer) and a certified well contractor. In the case of a permanent abandonment, the entire depth of the well is filled with a material such as Portland cement, gravel, or bentonite clay. The method and material used are somewhat dependent upon the type of well to be abandoned, whether the casing depth is known and how deep the well is. Wells are considered temporarily abandoned if the casing is securely sealed and the well head is covered with some sort of protective covering. Temporary abandonment, while not the preferred method in terms of protecting the aquifer, is more likely the choice for homeowners due to the significantly lower cost. The only way to truly protect the aquifer is to permanently abandon any unused well.
Three Ways to Help:
For more information, please contact Lisa Corbitt.
Well Information System
Groundwater and Wastewater Services
NC DEQ Groundwater Protection
Citizen involvement is an integral part of protecting our water resources, and with so many streams and large lakes in Mecklenburg County we rely on citizens to be our eyes in the field. There are
eleven volunteer programs related to water quality. These programs are offered as a way for residents to make a long term commitment to a neighborhood stream or groundwater aquifer. Residents can take control of their environment by volunteering a couple of hours a year or simply taking the time to report unusual stream conditions.
In Fiscal Year 2016, more than 2,800 volunteers participated in cleaning up local waterways, planting tree seedlings near streams, and/or marking storm drains with the message, "Do Not Dump, Drains to Creek." Volunteer programs are required of the City of Charlotte, Mecklenburg County and six surrounding towns through the
National Pollutant Discharge Elimination System permit, an element of the federal Clean Water Act. Join in with your neighbors or co-workers and make a difference in your local watershed.
For more information contact: