Watershed Protection
IN SOUTH DAKOTA

Statewide Lake Assessment Program

Lakes are an important part of South Dakota's culture and economy, and it is important to ensure that our state's lakes are protected for future generations. DENR monitors lakes throughout the state as part of the Statewide Lake Assessment Program. The goals of the Statewide Lake Assessment are:

  • Determine if lakes are meeting their water quality standards and supporting their beneficial uses.
  • Identify lakes for protection and restoration under the South Dakota 319 program.
  • Identify long-term trends in lake water quality and habitat condition.

Statewide Lake Assessment Program Resources

To learn how, when, where, and why we collect data for the Statewide Lake Assessment program, scroll through the storymap below or view it in fullscreen here.

Every year, a portion of the lakes in South Dakota are selected for monitoring based on a series of priorities, which are listed below.

  • Integrated Report Assessment: Lakes with a nonsupport status that require updated data to determine status (EPA categories 4a and 5). Lakes that lack water quality data to make an appropriate assessment determination (EPA categories 2 and 3), where desired.
  • TMDL Development: Lakes on the 303(d) Vision TMDL Priority Schedule. These are lakes scheduled for TMDL development and, as such, require sufficient data to calculate loadings and load reductions.
  • Publically Important: Lakes are divided into three tiers based on best professional judgment of economic value, recreation use, and public interest.
    1. Tier 1 - Lakes with the highest economic value, recreation use, and public interest. This tier is comprised of 44 lakes, of which approximately 18 will be visited 3 times each during a typical year. Each Tier 1 lake will be sampled four years out of every 10 years.
    2. Tier 2 - Lakes with significant economic value, recreation use, and public interest. This tier is comprised of 86 lakes, of which approximately 17 will be visited 3 times each during a typical year. Each Tier 2 lake will be sampled two years out of every 10 years.
    3. Tier 3 - Lakes with the least amount of economic value, recreation use, and public interest. This tier is comprised of 44 lakes. Tier 3 lakes will not be sampled as part of the Publicly Important priority. Sampling will occur only when data is required for the other priorities of the Statewide Lakes Assessment program, such as TMDL development and Integrated Report Assessment.

Priorities are not ranked in order of importance to allow flexibility on an annual basis to meet the needs of each specific priority and to integrate with other projects that engage in lake monitoring to prevent duplication of efforts. If the lakes monitored for the Integrated Report Assessment and TMDL Development priorities are in Tier 1 or Tier 2 of the Publicly Important priority, it will have little impact on the frequency that each lake is sampled over the course of a 10 year period. However, if Tier 3 lakes are sampled for the Integrated Report Assessment and TMDL Development priorities, some Tier 1 and Tier 2 lakes may be sampled less frequently.