To support recreation on Deep Creek Lake, lake levels should be maintained above elevation 2,458 ft. from early May through mid-October. Drawdown also should be limited each month to permit adjustment of boat docks. To minimize the potential for erosion of sensitive lake shoreline areas, lake levels should not exceed 2461.0 ft. To reduce the potential for entrainment of walleye and perch fry, generation during the early spring should be minimized. To maintain power and energy benefits, the project should continue to operate as a peaking plant, available to generate a minimum of two hours per day on any given week day. Generation is normally scheduled during weekdays to take advantage of relatively higher power values. The figure to the right illustrates the current rule band for operating the project to maintain the desired lake levels to achieve these objectives.
Releases of water from the Deep Creek Station can have a pronounced impact on dissolved oxygen (DO) in the Youghiogheny River, particularly during the summer months (click here for figure). A feasibility study was conducted in the early 1990's of alternative ways to meet Maryland DO standards and identified a tailrace weir and an oxygen injection system as the most promising alternatives. The tailrace weir was determined to be the most practical and cost-effective solution to correct the DO problem. The tailrace weir, basically a small waterfall which aerates the water after discharge from the power plant, was constructed and ready for operation in December 1994. It is shaped like a "W" to provide the required 430 length needed for aeration within the 40 foot tailrace channel. It is 8.4 feet high and results in a reduction in energy production of about 1% due to headloss. Results show that it is very effective at improving DO in the tailrace at startup. Even with a discharge DO level of less than 0.5 parts per million (ppm), the tailrace DO was never lower than 4.9 ppm. Uptake rates of DO ranged from 0.5 to 4.5 ppm, depending on the discharge DO level.
Many variables have affected trout populations numbers in the Youghiogheny River since 1987 when MDNR began sampling. These factors include drought summers (e.g., 1987, 1988, 1991, 1999), variable stocking rates, unknown harvest, the catch and release regulations implemented in 1993, and the habitat temperature enhancement measures implemented in 1995. However, standing crop estimates indicate an improving population at Hoyes Run. Measurements at Sang Run are more uncertain due to greater difficulty in sampling in that portion of the river.
The temperature enhancement protocol was formally implemented in the summer of 1995. The figure to the left shows river temperatures on a typical hot summer day when releases from Deep Creek Station keep the water cool. A report evaluating results for 1995 through 2008 is available in pdf format, Youghiogheny River Temperature Enhancement Protocol for Operating Deep Creek Hydroelectric Station: Model Development and Results for 1995-2008.
Implementation of the temperature enhancement protocol between 1995 and 2008 was very successful at maintaining lower temperatures than would otherwise have occurred in the river without the releases. In summary, the total number of days on which temperature exceeded 25°C at Sang Run ranged from 3 in 1996, 2000, and 2003, to 25 in 2005. Temperatures in excess of 25°C at Sang Run without operation of the DCHS (as represented by data from the Swallow Falls or Deep Creek stations) would have occurred on a minimum of 0 days in 2003 to a maximum of 67 days in 1999. Maximum river temperature at Sang Run exceeded 27°C 16 times from 1995 through 2008; maximum temperature exceeded 25°C 162 times, and 64 of those days exceeded 26°C; 61% of the exceedances were less than 26°C. Data from Swallow Falls suggest that there were very few days when releasing water for temperature enhancement was unnecessary (see table below; click to enlarge).
PPRP's survey of private whitewater boating
counted a total of 2,356 boaters from June 7 to October 14, 1996 and 4,249 boaters from
April 18 to October 13, 1997. The total number of private boaters projected for the entire
boating season (April 15 through October 15) was 3,510 for 1996 and 4,398 for 1997, when
adjusted for days not surveyed. In comparison, there were 3,050 and 3,356 commercial raft
customers reported for 1996 and 1997, respectively. Seventy-seven percent of boaters used
the scheduled whitewater releases in 1996 while over 97% used these releases in 1997, a
year in which fewer days were available with boatable natural flows or other scheduled and
announced releases. Only a small percentage used natural flows, temperature enhancement
releases, or other unscheduled releases. Most boaters surveyed reside in Maryland, Ohio,
Pennsylvania, or West Virginia. A total of 41 states including the District of Columbia
and 11 foreign countries were represented.