Surface Water Quality

​​Quality of Streams & Lakes​

When out on our lakes and streams, be mindful of water conditions. If it has rained in the past 72 hours, it is best to avoid swimming in coves as they are the main area where stormwater empties into the lakes, often carrying sediment and bacteria.

​​​​​​​​​​​​​​​​​​​​​​​Information about the quality of local streams and lakes is organized as follows. Please scroll down for more information about these topics.

Swimming Advisories​

A Swimming Advisory is issued by Charlotte-Mecklenburg Storm Water Services, in conjunction with the Mecklenburg County Health Department, when a natural body of water is considered a public health threat for swimmers. Examples of conditions that may cause an Advisory include a sewage spill, a chemical spill, Harmful Algal Bloom (HAB) or unsafe chemical or biological levels identified during routine monitoring. Once an Advisory is issued, the water is typically tested once a day until it is considered safe for swimming.

Harmful Algal Blooms (HABs)

Lakes

​The Lake Use-Support Index (LUSI) was developed to communicate vast amounts of surface water quality monitoring data collected from Lake Norman (with Lake Davidson and Lake Cornelius), Mountain Island Lake, and Lake Wylie along the western border of Mecklenburg County. These scores are updated every other month and represent data collected six times a year from 28 monitoring sites. The LUSI is constructed around four categories of surface water quality data that represent the most important pollutants and indicators of environmental health including:

  • Bacteriological (fecal coliform and e. coli)

  • Metals (arsenic, barium, cadmium, chromium, copper, lead, manganese, nickel, selenium, zinc)

  • Nutrients (chlorophyll A, nitrogen, phosphorus, nitrates, nitrites)

  • Physical (temperature, pH, dissolved oxygen)

Scores range from 0-100, with a score of 100 indicating the best surface water quality possible. The LUSI maps also include icons that also show where it is safe for swimming.

Fish Consumption Advisories

No Wake Zones for Lakes in Mecklenburg County

A No Wake Zone is an area of a lake or river where vessels are required to travel at an idle speed or a slow speed so no appreciable wake is created. No Wake Zones are typically defined by floating buoys. Only the Marine Commissions and the NC Wildlife Resources Commission can approve a No Wake Zone.

Mecklenburg County’s process for establishing a No Wake Zone, starting with submittal of an application, can take between one and two years to complete. The process is summarized as follows:

  1. Mecklenburg County Board of County Commissioners (BOCC) advertises in a local newspaper the date, time and location of a public hearing on the No Wake Zone proposal.

  2. The BOCC holds a public hearing and votes to approve or deny the proposal.

  3. If approved, the County will submit the necessary paperwork to the Wildlife Resources Commission.

  4. If approved by the Wildlife Resources Commission, the County will install and maintain buoys identifying the No Wake Zone.

Streams

The Stream Use Support Index (SUSI) was developed to communicate vast amounts of surface water quality monitoring data that is collected from streams throughout the City of Charlotte and Mecklenburg County. The scores are updated quarterly and represent data collected 12 times a year from 24 monitoring sites. The SUSI, or score, is constructed around five categories of surface water quality data that represent the most important pollutants and indicators of environmental health including each year. This index or score is constructed around five categories of surface water quality data that represent the most important pollutants and indicators of environmental health including:

  • Bacteriological

  • Metals

  • Nutrients

  • Physical

  • Biological