The actuality and possibility of flooding in Merced County has certainly been in the news for the last few months. The town of Planada and some parts of Merced were greatly affected by these massive flooding issues. The citizens of these areas were and still are suffering emotionally and financially from these events.
The unusual weather patterns of this winter with almost twice the normal rain and snow have certainly helped to pull us out of a drought but have caused other issues.
The lakes are having to release water early to allow room for the melting snows in the future. Productive agricultural land is not able to be farmed which not only hurts the land owners, but people are not able to work and create income for their families.
The very fertile Tulare Lake Basin may not be able to be farmed all year. The melting snow is going to keep rivers flowing at max capacity for several months to come. Some roads and lands in Merced County are closed to vehicle traffic and will take a while for water to subside enough to be able to work the fields and drive on the roads.
To better understand these water issues, let’s look at the environment surrounding our area.
Merced County is bordered to the east by the Sierra Nevada and to the west with the Diablo Range. Streams and rivers that descend from these ranges to the flat San Joaquin Valley can cause a flooding issue. Our valley can experience two types of flooding (1) general rainfall and (2) snowmelt floods, or both combined. Central parts of our county are especially prone to floods.
To help address this problem since the late 1940s and early 1950s, a series of four flood control dams were built in Merced and Mariposa Counties, on Burns, Bear, Owens and Mariposa creeks. These dams were designed to control foothill and mountain water drainage and have ungated outlets — meaning that during a flooding event modified releases are not possible. The Black Rascal Creek Watershed is the only remaining watershed which flows through the city of Merced that is not controlled. Some flooding occurs on an almost annual basis causing damage to personal property, roads, bridges, valuable agricultural land/crops and much more.
To address this problem a series of flood control improvements were implemented under what is called the Merced Streams Group (MSG) project. The MSG consists of three agencies: the City of Merced, Merced County and the Merced Irrigation District. The improvements included maintenance of channels downstream to increase flow capacities, maintenance of levees and modifications of bed and banks along with erosion control measures. Channel maintenance is necessary for a number of reasons. In some areas, the soils are highly susceptible to erosion. As stream banks erode soil is washed into the channel and flow capacity is reduced. Capacity is also reduced by trees, shrubs, debris, fallen trees and aquatic vegetation that has accumulated in the channel. These are the primary issues that restrict the water flow in the channel and help to cause flooding. For the MSG to maintain maximum stream capacity and control erosion, a routine maintenance program of the eastern Merced County creeks needs to be an ongoing practice.
The County proposes to continue the Flood Control Maintenance Program throughout the authorized areas within Merced County. The program has been in place for numerous years. Because the program involves activities within the bed and bank of creeks and streams, this program has been subject to state regulations for the protection of lakes and streams in the state. The maintenance program has been implemented under the Programmatic Stream Maintenance Agreement with the California Department of Fish and Wildlife (CDFW). The current agreement has expired (2019). In order to continue the program, the process requires the submission of a notification so that the proposed activities can be reviewed by the CDFW, and new Lake and Streambed Alteration Agreements (SAA) can be executed. CDFW has informed the County that the notification must be accompanied by a duly-approved CEQA compliance document. Therefore, the purpose of this is to evaluate the environmental effects from the continued implementation of the maintenance program.
A very vigorous stream channel maintenance program is needed to help reduce the effects of flooding. The approval of this program should be put on a fast track by the appropriate agencies to hopefully lessen the chances of the 2023 floods happening again.
Flood control dams in the Merced area:
- Bear Creek Dam was built in 1954 and is 92 feet tall, 1,830 feet long, has a 265-acre surface area, and will hold 12,700 acre feet of water. The outlet pipe allows a flow of 21,400 cfps. (cubic feet of water per second)
- Burns Creek Dam was built in 1950, is 65 feet tall, 4,070 feet long, has a 670-acre surface area and will hold 21,836 acre feet of water. The outlet allows a flow of 6,600 cfps. Burns Creek flows into Bear Creek east of Merced.
- Owens Creek Dam was built in 1949 and is 72 feet tall, with a length of 790 feet, has a 175-acre surface area, and will hold 6,075 acre feet of water. The outlet allows a flow of 7,300 cfps.
- Mariposa Creek Dam was built in 1948 and is 88 feet tall and 1,330 feet long, has a 510-acre surface area and holds 21,500 acre feet of water. The outlet has a flow of 30,000 cfps.
- Black Rascal Creek is a major tributary of Bear Creek and still does not have a dam to help control the flow. It was originally planned for the US Army Corp of Engineers to build the dam (Haystack Dam) around 1990 but because of environmental issues, the construction was delayed and funding eventually lost. The MSG is still planning to build the dam when all approvals and funding can be obtained. This much needed project, when completed, will help reduce the chances of flooding in our area.
Jim Cunningham and Flip Hassett are both retired, but they remain active in Merced County as community advocates, local history buffs and photographers.