By Darvin McClellan
People have speculated that Fort Gibson Lake is held higher and longer than other lakes in the area, such as Grand and Hudson. This column will explain the process of how we operate our lakes as a total flood damage reduction system.
The primary responsibility for Fort Gibson Lake — and all U.S. Army Corps of Engineers water resources projects — is to reduce or prevent flooding of private property.
The three major rivers in this area are the Grand (Neosho), Verdigris and Arkansas rivers. The Grand River feeds three lakes in Oklahoma —Grand, Hudson and Fort Gibson. Grand and Hudson lakes are operated by Grand River Dam Authority until they reach what is known as “flood levels.”
At that point, the Corps manages the water in the flood pool.
During times of heavy rains, a team of Corps of Engineers’ personnel in the hydrology division in the Tulsa District Office monitor all the drainages that run through Oklahoma. They receive information from stream gages that monitor water flows and rain gauges that capture local rain amounts.
Watch video below.
These numbers are used to determine which of the 44 lakes that Tulsa District manages for flood control should release water, as well as how much should be released to minimize impact to private property downstream.
Simply considering how many feet a lake is above normal can be misleading. The more important number is the percentage of flood storage being used. Grand and Hudson lakes have far less flood storage than Fort Gibson.
As an example, either Grand or Hudson could be 10 feet above normal, but using a much greater percentage of flood storage than Fort Gibson at 15 feet above normal. Fort Gibson Lake can rise 28 feet above normal pool level before private property is affected, while Grand can rise only 5 to 8 feet before affecting private property.
Fort Gibson also may need to hold water longer because it is the last flood damage reduction structure on the Grand River before water enters the Arkansas River.
Rain falling in areas along the Arkansas River where there are no flood damage reduction reservoirs could have already filled the river bank full. Releases from Fort Gibson will have a direct effect on possible flooding from Muskogee to Van Buren, Ark.
Many times the lake may be holding water to allow downstream flooding to subside. This is known as balancing the system. Often the downstream flooding may be many miles from a particular dam but if flood water releases were made, downstream flooding could be devastating to life and property.
It’s also important to realize that even after flood waters have been released from the lake, lots of work remains to be done.
Before camping areas can be reopened, Corps personnel have to insure parks are safe for use. This involves flushing hydrants, checking electric, removing debris and roads and campsites have to be inspected for any erosion.
We understand that high lake levels have an impact on our customers.
Our goal is to re-open our parks and provide access to the lake as soon as the water recedes and the facilities are safe. Volunteers are an important resource for the lake and help get the parks back in operation as soon as possible.
Individuals or groups can apply to become part of the team that helps speed the clean-up by contacting the lake office at 682-4314.
Darvin McClellan is a park ranger at the Fort Gibson Lake office.
