Ackley Lake Dam History
- Earthen dam constructed in 1938
- Off-stream reservoir with canal from Judith River
- Dam owned by DNRC, operated/maintained by Ackley Lake Water Users Association since 1938
- Primary Purpose(s): Irrigation, recreation, Ackley Lake State Park - northern half of the reservoir
- Dam Height: 51 feet
- Dam Storage: 6,722 acre-feet
- Dam Classification: High Hazard
Project History
After initial construction of the dam, a slide developed on the left side of the outlet near the toe of the dam. The outlet conduit was extended 120 feet and additional drainage was installed in an attempt to stabilize the slide. Investigative drilling in 1999 revealed high artesian pressures at the toe of the dam and in 2004 a seepage exit was observed to be transporting small quantities of fine grained material. Further analysis revealed that the dam did not meet stability requirements. A rehabilitation project was initiated to address the high uplift pressures, improve spillway performance and to line the aged, corrugated metal pipe outlet.
Work Breakdown
- Installation of toe drains
- Construction of a toe berm to protect against high artesian pressure
- Outlet conduit lining and extension to accommodate stability berm
- Installation of articulated concrete block primary spillway crest structure
- Leveling of dam crest
- Construction of auxiliary spillway
-
New Gatehouse
Project Funding
The total cost of the project was $1.6 Million.To finance the project, the DNRC used the following grant and loan programs:
- DNRC RRGL Grant: $100,000
- DNRC RRGL Loan: $200,000
- 20 years @ 4.5%
- To be repaid by WUA
- State funds: $1.3 Million
- Only utilized on SWP owned projects
- Ackley Lake Water Users Association:
- Increase in water users fees due to loans
Project Status & Results
- Construction began in 2008 and was completed in 2009
Project Partners
Owner: DNRC
Lead Design Engineer: DOWL
Prime Contractor: Mungas Company Inc.
