For Drought SWAP wells, permit conditions limit use of the deep aquifer well to periods when the daily reported streamflow level goes below an established threshold. At that time, the permittee is required to cease use of the surface water withdrawal and use only the deep aquifer well. In some cases, the Drought SWAP well may be only a partial replacement of the surface water withdrawal, and in those cases, the permit will specify conditions that offset and reduce the surface water withdrawal to the extent possible. The flow threshold is the 10^th percentile daily flow, on a monthly basis. The flow threshold is set at a nearby USGS gage, and GAEPD communicates through text, email, and/or its website when a Drought SWAP requirement is in place. The calculation of the 10^th percentile is based on the full period of record for that gage. Use of the deep aquifer well must be continued until flows exceed the threshold daily flow. This approach is the most practicable for on-farm management as well as for the Applicant’s oversight of compliance with permit provisions.