Many western San Joaquin Valley basins contain naturally high-nitrate soils that may cause problems, especially when used for irrigated agriculture when nitrogen fertilizer is added.

Appreciation is expressed to the following, who permitted the senior author to work and sample on their property: Mr. Orville Bert (Harris Feeding Co.) and Mr. Phillip Martin, from the Cantua Creek area, and Mr. John “Jack” Arbura and Mrs. Elena Talbot, from the Ortigalita Creek area. Dr. Patrick Sullivan, Department of Natural Resources, Ball State University, Muncie, Ind., contributed valuable field and laboratory assistance.