Hydrology of annual winter water level drawdown regimes in recreational lakes of Massachusetts, United States

Carmignani JR, Roy AH, Stolarski JT, Richards T. 2021. Hydrology of annual winter water level drawdown regimes in recreational lakes of Massachusetts, United States. Lake Reserv Manage. XX: XXX-XXX. Annual winter water level drawdown (WD) is a common lake management strategy to maintain recreational value by controlling nuisance macrophytes and preventing ice damage to shoreline infrastructure in lakes of the northeastern United States. The state of Massachusetts provides general guidelines for lake managers to implement and practice WDs. However, WD management reporting is not required and as such empirical water level records are scarce, making it difficult to assess guideline adherence and link these management actions to littoral habitat conditions. We monitored water levels bihourly in 18 lakes with ongoing WD regimes and 3 non-drawdown lakes over 3-4 yr. Our results show an interlake drawdown magnitude gradient of 0.07-2.66 m with intralake consistency across years. Corresponding WD magnitudes generated exposure of 1.3-37.6% for entire lakebeds and 9.2-71.1% for littoral zones. WD durations averaged 171 d and ranged widely from 5 to 246 d. Longer recession and refill phase durations and faster recession rates were moderately to strongly correlated with drawdown magnitudes. WDs were predominantly initiated prior to the state of Massachusetts 1 November starting guideline (83.1%) and refilled to summer reference levels after the recommended date of 1 April (70.6%). To minimize ecological impacts while still meeting recreational goals, WD performance guidelines may require a more fine-scale approach that integrates local hydrogeomorphic features and the presence of WD-sensitive littoral biotic assemblages. However, climate change model projections of warmer and wetter winters in the Northeast indicate increasing uncertainty for WD as an effective and worthwhile macrophyte control tool.