Project Operations Model
The Deep Creek Station hydroelectric project is operated to meet the following
objectives:
- maintain project capacity, energy, and reliability,
- support recreation on Deep Creek Lake,
- enhance fishing and fish habitat in the Youghiogheny River,
- enhance water temperature habitat in the Youghiogheny River for brown and rainbow trout,
- enhance whitewater boating opportunities in the Youghiogheny River,
- minimize the potential for lake shoreline erosion, and
- reduce the potential for entrainment of walleye and perch fry.
These objectives sometimes conflict, and consideration of all of them
together requires a balancing of the operating priorities and benefits
among them. A computer model of historical lake inflow, storage, and generation
was developed to simulate historical operation and to evaluate alternative
operating strategies. A number of cases were analyzed that included combinations
of minimum instream flows, habitat temperature enhancement, whitewater
enhancement, monthly allowable drawdown, and operating rule bands using
the computer model. Monthly operating rules for the Deep Creek Project
were developed in consultation with Power Plant Research Program to balance the objectives outlined
above.
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River Temperature Model
Deep Creek Station discharges into the Youghiogheny River in a peaking mode, resulting
in rapid and dramatic changes in flow and temperature in the river. During low flow
periods in summer, cold water releases from the project can provide a benefit to the trout
fishery in the river by moderating otherwise unfavorable low flows and high temperatures.
The Power Plant Research Program sponsored a temperature model of the river using the Corps of Engineers river water
quality model CE-QUAL-RIV1 to evaluate the effectiveness of various release scenarios for
maintaining water temperature below a critical value for brown trout. Temperatures were
recorded continuously at 10-30 minute intervals for several summers at various locations
in the river to provide data for model calibration and verification. Model simulations and
test releases included both full and partial generation releases of 1-3 hours in duration
at mid-day and during several continuous low flow releases. Results were then used to
estimate the relative cost of various release scenarios to the utility and other users of
river flows of various release scenarios. Results showed that a 2-unit release from Deep
Creek Station for 2 hours starting at 11 AM would provide sufficient water to maintain the
river temperature less than 25°C even under extreme low flow and high water temperature
conditions (here is the graph). Model
results were also used in determining a means of triggering releases when required, based
on daily meteorological forecasts, flows, and temperature conditions in the river.
The complete model report is available (
A Temperature Simulation Model of the Youghiogheny River from Deep Creek
Station to Sang Run)
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Fisheries Habitat Modeling
Effects of flow on fish habitat were evaluated in the Youghiogheny River below
the Deep Creek Station tailrace. This instream flow study employed PHABSIM,
the Physical Habitat Simulation system developed and supported by the U.S.
Fish and Wildlife Service. This system is essentially a series of analytical
procedures and computer programs used to conduct hydraulic and habitat simulations.
It is used to evaluate the effect of river flow on physical habitat variables
in the river, including depth, substrate, velocity, and cover. Relationships
between flow and fish habitat in the river can then be determined. The relative
amount of usable habitat as a function of river flow was estimated, based
on habitat suitability information for brown trout, identified as the most
important gamefish in the Youghiogheny below the tailrace. Results show
the optimal flow for brown trout fry, juveniles and adults is 250, 275,
and 300 cubic feet per second, respectively.
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River Recreation Survey
The Power Plant Research Program conducted a survey of recreational boating usage in 1996 and
1997. The survey was designed to measure river usage whenever there was a release
from Deep Creek Station usable for whitewater boating (between the hours of 6 am to 1 pm
at the station) or when the natural flow in the river was suitable for whitewater boating
(greater than about 300 cfs at Oakland or about 1.9 feet on the Sang Run gage). A 2-person
field crew conducted the Youghiogheny River boating survey, recording information on the
total number of boats and other information about the users.
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Temperature Enhancement Operations Protocols
Power Plant Research Program sponsored development of a protocol for predicting maximum daily river temperature
during summer using measurements of river flow and temperature changes in the river and
available predictions of maximum air temperature and cloud cover in the region. The
protocol consists of a series of equations (developed using multiple regression models) to
be used by plant operators during the morning and afternoon to predict river temperature.
The operators then use these predictions to decide whether to make a release to cool the
river, thereby enhancing temperature habitat for trout. The target maximum river
temperature is 25°C (77°F), a maximum value for brown trout habitat. The operators also
use the predictions to make a publicly available telephone recording that a release will
be made so that whitewater boaters can take advantage of the release.
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