SACRAMENTO, Calif. (KTXL) — Flooding from a New Year’s Eve storm impacted roadways and caused evacuations in certain areas in Sacramento County. 

One of the flooded roadways was a stretch of Highway 99 between Elk Grove and Galt on Jan. 1. Sacramento County officials told FOX40 News that three levees on the Cosumnes River were breached. 

The Rio Cosumnes Correction Center also had a threat of a flood, causing the evacuation of 1,075 inmates, after weather conditions worsened and road conditions eroded nearby. 

Compared to the Sacramento and American rivers, the Cosumnes River is different due to it not having a major dam.

According to the Water Education Foundation, the Cosumnes River is the only one west of the Sierra Nevada without major dams. Due to no dams attached, the river endures seasonal overbank flooding, the Water Foundation said. 

Where does the river flow? 

The Cosumnes River flows about 52.5 miles into the Central Valley, merging with the Mokelumne River in the Sacramento-San Joaquin Delta at Mokelumne City. Towns and cities along the Cosumnes River include Plymouth, Rancho Murieta, Sloughhouse, Wilton, Elk Grove, and Galt. 

According to the Water Foundation, the river goes under Highway 99 near Elk Grove and into the Consumes River Preserve, which has some of Central Valley’s largest wetlands and riparian areas. A riparian area or zone typically is along streams, rivers, lakes, ponds, and wetlands, according to the United States Department of Agriculture. 

The forks in the Cosumnes River

The river has three forks that go through El Dorado and Amador counties and all three eventually combine. 

Here is where the forks flow: 

The river’s north fork is 40 miles long and begins at Singleton Springs in El Dorado County, which is about 10 miles southwest of Kirkwood Ski Resort. The north fork then flows west and into Camp Creek and continues through the granite narrows of the Cosumnes River Gorge and joins the middle fork. 

The middle fork is 44.5 miles long and also starts in El Dorado County, flowing parallel to the north fork. The river flows through a canyon through Dogtown Creek at Omo Ranch and flows past Outingdale in a valley. 

The south fork of the river is the shortest, being 20 miles long and flowing northwest along the El Dorado and Amador County line before connecting with the middle fork. Shortly after, all forks combine and the river continues west through the Sierra foothills, Michigan Bar, and then into the southern portion of Sacramento County. 

When flowing through south Sacramento County, the river flows west through Rancho Murrieta, continues through agricultural land, and past Sloughhouse. After going past Sloughhouse, the river then goes under Highway 99 and eventually enters the Sacramento-San Joaquin River Delta to join the Mokelumne River.