On October 23, 2024, the New York State Department of Environmental Conservation issued a memo providing guidance regarding solar and stormwater management. This letter was issued in response to a number of questions presented by New York Solar Energy Industries Association, and includes the following key clarifications:

• Clarifies that a typical solar array "may be designed to be disconnected impervious area and qualify for impervious area reduction when computing water quality volume requirements."

• States that "panel spacing is consistent with the concept of disconnection of impervious area (Section

  5.3.4 of the 2024 White Book) and is an important component to consider when avoiding erosive conditions. Disconnection can be achieved through adequate spacing of panel rows over areas of well-established vegetative cover."

• Includes helpful diagrams 1 and 2 to show a typical array layout and defines the components to eliminate ambiguity.

• Clarifies that even if panels aren't “generally installed along the contour” of the earth, that doesn't mean the panels should be considered impervious.

• Clarifies that the area underneath solar panels installed on vegetated slopes of 8% or less can be considered a filter strip to meet WQv and RRv requirements (even when the panels are not installed along the contour).

• Notes that solar panels installed on slopes greater than 8% may implement permanent engineered practices from the Blue Book and White Book or use the NYSDEC Gravel Diaphragm detail (Diagram 3) along the slope/contour, to reestablish and maintain sheet flow, which will meet RRv and WQv requirements.

• Clarifies that pervious access roads are not required by the CGP and are not listed in the 2024 White

  Book and therefore are not required on renewable energy sites.

• Clarifies that the Maryland Department of the Environment (MDE) Stormwater Design Guidance referenced in a prior (2018) memo is not applicable in New York State.

• Acknowledges that well-designed projects on slopes steeper than 10 percent have successfully implemented some of the alternative practices mentioned such as flow diffusers and stone diaphragms.

Click READ MORE to view the full guidance document.