The 2020 “Class” of Grass Carp Has Been Released

On April 14, 600 sterile triploid grass carp were released into the Swift Creek Reservoir to help control the growth of the non-native hydrilla plant.  These carp represent the “Class of 2020” and they supplement the previous classes of carp added at various times since 2010.

The quantity of 600 carp was determined after studying the results of computer modeling runs using our best estimates of the amount of hydrilla consumed by carp of different sizes, carp predation/mortality, etc.  The model indicated that adding more than 600 carp could “collapse” the level of vegetation in the reservoir, an undesirable result.  Adding fewer than 600 carp could lead to higher levels of hydrilla than in recent years, also undesirable.  This is consistent with the current approach of adding a relatively constant number of carp each year to achieve a balance between overgrowth and collapse of vegetation.

This year, rather than the normal, very “public” release of the carp along Genito Rd., the carp were released at the Addison-Evans water treatment plant in order to streamline the process during the COVID-19 pandemic.  We owe a note of gratitude to the Chesterfield County Utilities Department for following through on their commitment to the residents around the reservoir to add carp this spring while they continue to supply high quality drinking water under difficult conditions.

We will continue to update you when important information becomes available and when public meetings are planned.

The Reservoir Hydrilla Management Group

John Cooling, Tony Giordano, George Hayes, Tom Hoekstra

Steve Menninger