The Corps of Engineers has predicted that flooding on the upper part of the Lower Missouri River this coming week is going to be historic. As the projected 150,000 cfs release from Gavins Point Dam propagates downstream, it will add to streamflows (presently about 200,000 cfs) that are already near flood stage. This will result in prolonged high flows throughout the Lower Missouri River in June. These flows will come closer to mimicking the natural spring flood than any floods encountered since the USGS Comprehensive Sturgeon Research Project began documenting sturgeon responses to flows in 2004. Ironically, it may be too much water to deal with.
In this extraordinary year, we’ve seen two females already complete their spawning migrations by mid-late May, one around rivermile 217 and the other up the James River in South Dakota. We still have the potential to follow 4 reproductive females that were implanted and released near the Platte River, but it will be challenging to locate them acoustically during flood flows when they move along the banks and into vegetated areas. In addition, we face a fundamental logistical challenge in finding boat ramps that are open, and if open, unclogged by mud and woody debris. And, of course, high velocities and abundant transported debris severely complicate recapture and larval sampling. Although conditions may prevent us from tracking these fish during high water, the tags implanted in them will continue to record depth and temperature, and we will retrieve the data when the fish are recaptured later this year. These data provide key insights into what high water really means to a sturgeon.
This coming week we will attempt to deploy additional crews upstream of the Platte River with the hope of finding our reproductive females before water gets too high to work safely. We are also actively tracking reproductive sturgeon on the Yellowstone River downstream of the Intake Diversion Dam in Montana and documenting depths and velocities along their migration routes.