Update on Hydrilla in Swift Creek

ReservoirMarch , 2018

Kenneth J. Wagner, Ph.D., CLMWater Resource Services

Chesterfield County UtilitiesGeorge Hayes, P.E., Director of UtilitiesScott Morris, P.E., Assistant Director O&MDavid Sirois, Plant ManagerScott Bookwalter, Biologist

Reservoir Hydrilla

Management Group

Tonight’s Presentation

Current Status Reports of Hydrilla in Swift Creek Reservoir

Review of Hydrilla Growth (2009-2017)Update on Primary Hydrilla Control

for 2018Secondary Hydrilla Control UpdateQ&A on Hydrilla ControlLG Sonic Update

2016-2017 Hydrilla Monitoring and Control Program Comparison

April 2017 — 0 acres April 2016 — 0 acres

May 2017 — 0 acres May 2016 — 50 acres

June 2017 — 253 acres June 2016 — 150 acres

July 2017 — 346 acres July 2016 — 45 acres

August 2017 — 588 acres August 2016 — 48 acres

September 2017 — 494 acres September 2016 — 61 acres

October 2017 — 566 acres October 2016 — 48 acres

November 2017 — 405 acres November 2016 — 5 acres

December 2017 — 29 acres December 2016 — 0 acres

2009-2017 Hydrilla Growth in the Swift Creek Reservoir

Primary Hydrilla Control for 2018

Primary Hydrilla Control Based on the carp and hydrilla biomass model stocking

rates and the impact of carp addition to the reservoir has been evaluated.

Recommending an application be submitted to Department of Game and Inland Fisheries for the addition of 500 Triploid Grass in April.

An April stocking will support the goal of introducing multiple classes of carp.

Chesterfield County will continue to monitor hydrilla growth, documenting peak growth in 2018.

Primary Hydrilla Control Multiple classes of fish in the reservoir will mimic the

natural reproductive cycle of non-sterile carp to minimize a population crash.

Subsequent additions of Triploid Grass carp will be based on level of control from previous years and peak growth, an emphasis on multiple classes will be followed.

Carp additions in 2019 and beyond will be based on maintaining a balanced approach for maintaining sufficient vegetation(10 to 25 percent coverage)to promote a healthy reservoir and to prevent a collapse in the carp population.

Primary Hydrilla Control Utilities will continue to monitor aquatic vegetation and

algae. We will continue to assess the carp/biomass balance through use of the model (developed in 2010 and revised in 2018). Virginia Game and Inland Fisheries will continue to try to assess fishery health (grass carp are skittish and have been found to be difficult to sample by electrofishing).

We will continue to evaluate and improve the model and overall program as more information is available.

Remember biological systems are difficult to control due to the many natural variables that affect them.

Primary Hydrilla Control Interactive Chart

Secondary Hydrilla Control

Secondary Hydrilla Control Utilities consulted with the RHMG leadership and the

RHMG leadership approved the purchased of pilot equipment with the available secondary control funds to test cutting and disposal of localized hydrilla.

Utilities has tested the equipment to establish protocol's for management of the secondary localized control program.

Secondary Hydrilla Control Cost of equipment: $3,100 In testing of the cutting of hydrilla, an area equivalent

to 300 feet in length by 75 feet wide was cut in approximately 5-6 hours.

Chesterfield County Utilities obtained permission from the State Virginia Marine Resources Commission (VMRC) allowing travel lanes to be cut in the aquatic vegetation of SCR. Other cutting is not allowed w/o VMRC permit and would be in violation of VA law.

Secondary Hydrilla Control The RHMG and associated HOA’s can establish a

service with a third party contractor to provide this year’s cutting of homeowner travel lanes (not to exceed 18 feet width) including proper collection and disposal of hydrilla.

RHMG is asking for volunteers to assist with establishing a committee to oversee the collection of a summary of interested homeowners to establish a pricing structure for an interested third party.

Q&A on Hydrilla Control

Current Algal Monitoring and Control Methods

Monitoring of Algae

Currently there are 8 monitoring stations maintained by Addison-Evans Water Production & Laboratory Facility (AEWPLF).

AEWPLF continues to stay current with scientific research and the literature in the drinking water field and identify the algae that frequent Swift Creek Reservoir and determine relative populations through microscopy.

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Current Algal Monitoring and Control Methods

Control of Algae

The drinking water field established method of adding copper sulfate in low concentrations to control algae has long been performed by AEWPLF to ensure water production will not be affected by algal populations. Approximately 3,000 pounds were used in 2016 to control algal growth.

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The Next Step in Algal Monitoring and Control-LG Sonic-

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LG Sonic combines the latest technologies for monitoring algal populations by continuous sensors, algal control by ultrasound,

and communication by sending data back to personal computers (PCs) for real time evaluation.

The Next Step in Algal Monitoring and Control-LG Sonic-

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Location

The Next Step in Algal Monitoring and Control-LG Sonic-

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How it Works Ultrasound sent by the LG Sonic MPC-Buoys will be the

correct frequency and power to destroy gas vesicles in the algae thereby causing them to sink and be unable to receive light needed for photosynthesis. By not physically destroying the algal cells and sinking them the immediate release of taste & odor compounds is prevented.

Impact to Environment The effects of LG Sonics ultrasound products have been

tested by various universities and proven to be safe for fish, plants, zooplankton and insects. The product was designed with environmental concerns and is solar powered. Over 10,000 of the LG Sonics products have been installed in over 52 countries, one of the most recent installation in the United States was in New Jersey. This installation is slated to be the first installation in a Virginia reservoir.

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Placement of equipment The ultrasonic range of the buoy is approximately 1600

feet, two buoys will be placed in the intake bay to effectively cover the entire intake bay.

Size of equipment 2.82 feet high 8.33 feet by 7.18 feet wide

Cost of equipment Approximately $98,000 for two units for intake bay

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Real Time Water Quality Data

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For more information, visit Chesterfield Utilities online:

chesterfield.gov/utilities