Since 2006 it has not been allowed to fill to more than 60% of capacity because of these issues. Youngdahl Consulting Group provided on-call geotechnical, geologic, and construction materials laboratory testing services to the U.S. Army Corps of Engineers during investigations and design work at Isabella Dam.  Our services have included the testing of:

• Rock Cores: unconfined compressive strength, triaxial shear strength

• Potential Concrete Aggregates:  Sulfate soundness, Los Angeles abrasion,
  specific gravity, gradation

• Concrete Mixing Water: concrete strength, water staining potential, time of
  concrete set

• Slope Protection Materials: rock wetting and drying, specific gravity, gradation

• Soils: Atterberg limits, Proctor curves, sieve analysis, hydrometer analysis