Town of Poolesville Water Capacity Informational Hearing
MCA contracted a veteran hydrogeologist to conduct a study into the future yields of Poolesville’s water supply. Result showed the current overallocation of water to the town had an impact on the sensitive Horse Penn Branch watershed. Droughts are forecasted to be more severe in the future combined with rising hot temperatures. Seasonal conservation measures will facilitate the current town population water limits however development will necessitate increased conservation measures and could cause some wells to dry up.
A presentation on water capacity was part of the Poolesville Town Commissioners Meeting held on 4/21/2025. Pat Hammond presented on future water capacity based on findings in his report A Study on the Reliable Drought Yields of Poolesville’s Public Water Supply Wells published in April 2024. Mr. Hammond’s presentation begins at 50:49 and his corresponding slide presentation is available here.
Comments of note.
"The Town Hydrogeologist denied the effects of climate change, indicating that they are so uncertain that they should not be considered in evaluating the Poolesville system yield, without any supporting documentation. The vast majority of climate scientists have demonstrated that climate change is real. The present authority in Maryland is the Instate commission on the Upper Potomac River Basin (ICPRB), who indicate that baseflow (effective recharge to Poolesville’s wells) will decrease an overall annual average of 15%, and by 3% to 33% in 16 out of 18 scenarios in their 2010 report on climate change in the upper Potomac River Basin. Mr. Hammond used 7 specific scenarios that produced a less conservative value of an annual average reduction in baseflow of 8.4%, and derived a drought year reduction of 16% in baseflow."
Underestimating high heat index days:
"The Town Hydrogeologist indicated that the assumption of 30 days of 100° F (taken from her 2021 report), to account for climate change was too conservative. They then stated that they knew of a reference that the maximum would be 5 days. The reference was not provided; however, a quick review of the literature indicated that 5 days would reflect historical data for Washington D.C., though the maximum was 11 days in 1931. Dahl et al. (2019), indicated the maximum number of days with a 100° F heat index is more than 50 under climate change through the year 2050."
Not taking stream impairment seriously:
"The Town Hydrogeologist used a groundwater flow model to explain why the MDE water balance methods should allow for allocations of water in Horsepenn Branch flowing from other watersheds, without mentioning that the watershed is already severely impaired."