We continue our series of stories by Southwest Ledger reporter Mike Ray into the controversial proposed hydroelectric project on the Kiamichi River in southeast Oklahoma.
By Mike W. Ray
Southwest Ledger
The 38.5 billion gallons of initial “fill” water for the three reservoirs that would be constructed for Southeast Oklahoma Power Corporation’s hydroelectric power plant in Pushmataha County – and “make-up” water to replace water lost from leaks, spills and evaporation – would be sucked out of the Kiamichi River through a concrete intake channel.
“It is estimated that the initial fill would be conducted” over a period of 24 to 30 months “based on the availability of flow in the Kiamichi River.”
After the upper and lower reservoirs were full, water in the re-regulating reservoir would be used “to provide maintenance flows to replace water lost to evaporation and leakage,” a report states. SEOPC estimated that maintenance flows would be approximately 20,000 acre-feet (6.5 billion gallons of water) each year.
(An acre-foot is equivalent to 325,851 gallons of water, enough to inundate an acre of land to a depth of 1 foot.)
Refill of the re-regulating reservoir would occur “throughout the year during high-flow periods when the Kiamichi River surface elevation reaches a minimum of 1.5 feet above the river bottom.” The re-regulating reservoir would need to be refilled “about 16 times a year to provide the estimated 20,000 a/f per year of maintenance flows,” SEOPC told FERC.
However, Charles Pratt of Tulsa, a civil engineer who specializes in hydroelectric power plants, is skeptical of the SEOPC project. “I’ve done work at just about every Corps of Engineers lake in Oklahoma, Missouri and Arkansas,” he said.
Pratt told the Southwest Ledger the estimated 20,000 a/f of replacement water for the SEOPC hydro plant is “woefully underestimated, in my opinion.”
To provide a rough idea of seasonal water losses from reservoirs in southeastern Oklahoma, here are some statistics from the U.S. Army Corps of Engineers for Broken Bow Lake in McCurtain County and Sardis Lake in Pushmataha County.
Broken Bow (14,200 surface acres): 7.068 inches evaporation in June and 7.037 inches in July this year; 1.935 inches evaporation in November and 1.56 inches evaporation in December last year.
Sardis Lake (13,590 surface acres, according to the Oklahoma Water Resources Board): 9.838 inches evaporation in June and 10.35 inches evaporation in July this year; 3.365 inches evaporation in November and 2.992 inches evaporation in December 2023.
At SEOPC’s request, HDR engineering services of Tulsa performed a “hydrology desktop study” to evaluate “extracting water from the Kiamichi River” for the initial fill of the corporation’s proposed Pushmataha County Pumped Storage Hydroelectric Project.
To provide “complete annual data sets,” the hydrologic evaluation examined a 23-year period: January 1995 through December 2017.
HDR reviewed the daily average water discharge at an upstream gauge on the river near Big Cedar (at the intersection of U.S. Highway 259 and State Highway 63, at the southern edge of Ouachita National Forest).
That review showed what local residents have long asserted: “the Kiamichi River had periods of very little to no flow between 1965 and present.”
Kiamichi has periods
of little to no flow
Weldon Robbins recalls 2011 as an exceptionally dry period along the river. His brother, Johnny Robbins, remembers he drove a Kawasaki Mule a mile and a quarter in the riverbed that year “and never got the tires wet.” Weldon Robbins owns 240 acres along the banks of the Kiamichi River, and Johnny Robbins has 20 acres of abutting property.
The river is “known to experience periods of low water or even no-flow during the summer and extended drought conditions that can result in disconnected pools along the river, the Oklahoma Water Resources Board reported in 2012.
Daily mean flows of less than 1 cubic foot per second (cfs) “were recorded at the U.S. Geological Survey (USGS) gauges near Clayton and Antlers approximately 7% and 6% of the time, respectively, during the period of record,” HDR wrote.
Furthermore, daily mean flows at the USGS gauge near Clayton were recorded at 0.0 cfs “approximately 3% of the time (272 days) during the period of record,” HDR reported.
And between October 1972 and December 1982 the Kiamichi River at the USGS gauge near Antlers “recorded extended periods of flows less than 1 cfs five times,” and those times ranged from five days to 56 days, HDR found.
“December through May tends to be characterized as the higher flow season, while … June through November tends to be characterized as the lower flow season,” HDR concluded.