OKLAHOMA CITY – The Oklahoma Water Resources Board approved a $39 million low-interest loan that the Lawton Water Authority will couple with grants totaling almost $14 million to finance repairs to the dams at Lakes Ellsworth and Lawtonka and to rehabilitate the Gondola Lake Dam.
The bulk of the funds – approximately $47 million – will be spent on the Lake Ellsworth Dam rehabilitation project, according to Public Utilities Director Rusty Whisenhunt. New bids on the project have been received, and the low bids must be awarded by April 9, he said. When the project was bid last year, only one proposal was received, and it was $61,585,000.
Ellsworth’s concrete spillway was damaged after heavy rains in 2015 forced the city to open the floodgates to release runoff water that otherwise would have topped the dam.
City officials knew from the outset that heavy runoff damaged concrete panels in the spillway. However, further analysis revealed other problems, such as empty spaces beneath the spillway that were identified after geotechnical and engineering analyses. The spillway “floated” during the water releases, Whisenhunt told Southwest Ledger.
Rehabilitation measures, the Oklahoma Water Resources Board reported, will include adding more robust rock anchors, additional drains beneath the apron, sealing cracks and casting a reinforced concrete slab over the existing apron, repairing concrete on the 363-foot-long spillway, retrofitting the spillway retaining walls, adding chute blocks on the spillway stilling basin, and adding riprap along the east side of the spillway.
The repairs will take approximately two years to complete, Whisenhunt said.
The Ellsworth dam is labeled a high-hazard structure because more than 5,200 people downstream would be at-risk if the dam failed, the OWRB explained.
According to the OWRB, the Ellsworth dam is a combination earth fill and concrete structure 3,900 feet long, 96 feet high, and 30 feet wide at the top. It has 15 gates, each 10 feet high and 20 feet wide.
Lake Ellsworth is northeast of Lawton, between Elgin and Apache, and straddles the Comanche/Caddo county line. It was built by the City of Lawton in 1962 as a source of drinking water and for recreation. The reservoir, an impoundment of East Cache Creek, encompasses 5,100 surface acres and has 53½ miles of shoreline.
The Lake Lawtonka dam has spalling damage and requires concrete rehabilitation, Whisenhunt said. Spalling refers to deterioration of the concrete surface, characterized by pitting, chipping, flaking, or peeling sections, often exposing the reinforcing steel bars beneath.
That repair project will cost an estimated $1.2 million, Whisenhunt said.
Lake Lawtonka is situated near Medicine Park and was created in 1905 by impounding Medicine Creek behind a dam 60 feet high and 375 feet long.
Gondola Lake dam slated for repair, too City-owned Gondola Dam is downstream of Lake Lawtonka and is used to create a small tilling pool.
The dam is approximately 100 years old and, “There is no as-built information, maintenance records, or previous inspection records” for the barrier, Whisenhunt informed the city council.
A concrete cap will be installed across Gondola Dam, Whisenhunt said. A 2-foot concrete top across the dam has been damaged and will be restored. “We’re also making it wide enough for a sidewalk and handrail for people to walk across,” he said.
The Lawton City Council hired Jacobs Engineering Group in June 2023 to perform preliminary design work on renovation of the century-old dam; that work is nearing completion, Whisenhunt told the Ledger last week. The Gondola Dam repairs will cost an estimated $3.2 million, he said.
The three dam rehabilitation projects will be financed with proceeds from the $39 million loan from the Clean Water State Revolving Fund (CWSRF), a $925,251 high-hazard dam grant from the Federal Emergency Management Agency, and $13 million in Oklahoma State Designated American Rescue Plan Act (ARPA) grants, city officials reported last month.
The CWSRF loan was approved March 18 and will be retired over a maximum period of 30 years with city utility revenues, OWRB records reflect. Lori Johnson, chief of the agency’s Financial Assistance Division, calculated that the Authority’s customers will save an estimated $11.1 million in interest charges compared to traditional financing.
According to Whisenhunt, Lake Ellsworth provides approximately 20% of Lawton’s water, Lake Waurika about 10%, and Lake Lawtonka is the city’s primary source of fresh water.