Lake Red Rock

About

Lake Red Rock, Iowa — 1969 Dam, 1840s-1880s Logging, 1990s-2010s Red Rock Lake Trail 50-mi Pella. Long before the dam, this stretch of the Des Moines River flowed through the ancestral territory of Indigenous peoples, serving as a travel corridor, hunting ground, and gathering place. The cession framework that displaced them was established through the 1800s-era treaties, the 1830 Indian Removal Act, and the allotment era spanning the 1840s to the 1890s. That earlier history set the terms for everything the valley would become.

From the 1830s through the 1920s, the watershed was logged to feed the regional timber industry of 1850 to the 1910s and the railroad expansion of 1860 to the 1910s. Local sawmills, logging drives, and downstream lumber operations were the major operators. The era closed on three fronts: the exhaustion of old-growth stands around 1910, the start of state forestry conservation in 1915, and the establishment of state forests in the 1930s. What the loggers left behind, the surveyors began to measure.

The first comprehensive hydrological studies of the river came from the USGS survey work of the 1870s to the 1890s, the gauging-station establishment of the 1880s to the 1910s, and the state geological survey streamflow assessments of the 1910s to the 1930s. Later, the state water pollution control studies of the 1950s to the 1970s and the Clean Water Act assessments from 1972 to 2000 confronted more than a century of logging, agricultural, and industrial impact. Modern TMDL and restoration programs are the major current outcomes of that long accounting.

Then came 1969 and the dam itself. Its purpose was flood control — curbing the Des Moines River and, downstream, the Mississippi that the basin ultimately feeds. Relocation was no small matter, for the rising water swallowed six towns whole, which is why a full third of the budget went to moving infrastructure and cemeteries. When the reservoir filled, it became Iowa's largest lake at more than 15,000 acres of surface water, holding back a river that drains over 12,000 square miles. The lake carries a Class I rating and an optimal flow window of 90 to 275 CFS, gauged at USGS station 05451210, which averages 181 CFS.

Recovery work continues on the water the dam created. Since 2010, the Iowa DNR, working with local watershed partnerships, has addressed the accumulated impacts of a century of land use. The streambank stabilization of 2015 to 2024, the native fish restocking of 2017 to 2024, the nutrient reduction strategy implementation begun in 2018, and the water-quality improvements of 2020 to 2024 mark the recent chapters. Today Lake Red Rock is a Designated Water Trail under the US Army Corps of Engineers, carrying the Red Rock National Water Trail. The lake supports the Pella, Knoxville, and Pleasantville economies and is home to Elk Rock State Park and the Marion County Park — a reservoir whose calm 36-mile expanse still conceals the towns it replaced.