1

POTOMAC RIVER POTOMAC RIVER FLOWBY FLOWBY

WORKSHOP: WORKSHOP: IntroductionIntroduction

OUTLINE OF PRESENTATIONOUTLINE OF PRESENTATION

Background

Review of 1981 flow-by study

Objectives of new flowby study

Objectives of workshop

BACKGROUNDBACKGROUND

Current agreement: 100 mgd below Little Falls Dam

300 mgd recommendation below Great Falls to Little Falls Dam

Study Required by Low-Flow Allocation Agreement (LFAA)

Signatories: COE-WAD, MD, VA, DC, FCWA, WSSC

Augmentation releases determined and requested by ICPRB

REVIEW OF REVIEW OF 1981 STUDY1981 STUDY 1981 study itself and others identified shortcomings 100/300 mgd flow-by not environmentally based (or

if so, not documented)

“ A daily average flow below Little Falls Dam of 100 mgd is nearly the limit of what the current system can provide during extreme drought conditions...”

Lowest measured flow for the 1981 study was 900 mgd (1400 cfs)

REVIEW OF 1981 STUDY, REVIEW OF 1981 STUDY, cont.cont.

1999 drought prompted reconsideration of the flow-by issues

Habitat Assessment Subcommittee (HAS), subset of the Potomac River Flow-By Evaluation Committee organized to revisit 1981 study due to shortcomings and new information

CURRENT OBJECTIVESCURRENT OBJECTIVES

Estimate the amount and quality of biotic habitat available at different flow levels, particularly as it relates to the current minimum flow-by requirement,

SHORT-TERM

CURRENT OBJECTIVESCURRENT OBJECTIVES

Determine what instream flows are required to provide adequate aquatic habitat and to prevent a reduction of any representative important species beyond levels from which it cannot recover and re-colonize the area following a drought event.

LONG-TERM

WORKSHOP STRUCTUREWORKSHOP STRUCTURE Assemble experts in riverine habitat assessment to advise the

Subcommittee on the best means of achieving the Potomac Flow-by Study objectives.

Experts to present and discuss their views on the best means of addressing the objectives.

Experts to recommend the best analysis techniques and related data collection considerations for our specific situation:

• Extreme & infrequent drought conditions

WORKSHOP PURPOSEWORKSHOP PURPOSE Assess methodologies to evaluate flow-by requirements of

the Potomac River to provide the following recommendations to the Habitat Assessment Committee:

• The most favorable methodology, given current financial resource limitations, to address the Potomac River Flow-by Study objectives; and

• An alternative long-term methodology that could better accomplish those objectives, yet might exceed current resources or available data, and recommended guidelines for achieving the objectives in a longer time-frame.

FUTURE DIRECTIONSFUTURE DIRECTIONS

Workshop summary report including panel recommendations

Report distributed for comment Final report to Habitat Assessment

Subcommittee (HAS) HAS recommendation to full Potomac

Flow-by Committee for further action