FA BLM AZ Lake Havasu Watershed/Water Quality Assessment
Project Background Information: Lake Havasu City (City) is a growing community of 53,000 residents situated on the banks of Lake Havasu in Mohave County, Arizona. The City covers an area equivalent to 42 square miles with ten major drainage sub-basins routed through the City carrying runoff flows into Lake Havasu. The City¿s corporate limits extend to the high water mark of Lake Havasu at 450¿ above mean sea level. Lake Havasu City is working to implement an Arizona Department of Environmental Quality (ADEQ) approved Storm water Management Plan that intends to identify, mitigate, and manage potential water pollution threats to Lake Havasu from these periodic flows through the City and into the lake. BLM administers the lands below 450¿ elevation in Lake Havasu for recreation and wildlife purposes, which has been delegated to the BLM from the Department of the Interior on behalf of the Bureau of Reclamation. The lake levels fluctuate from approximately 445¿ to 449.5¿ depending on the season and these areas provide the lake interface that is subject storm waters. It is important that Lake Havasu water quality is retained at a level that satisfies standards for recreation, fish and wildlife, domestic, industrial, and irrigation purposes. In cooperation with BLM, Lake Havasu City developed an agreeable sampling and assessment study/sampling protocol. The City has diligently pursued the purpose and intent of the project, by mapping and assessing existing conditions, and sampling surface and ground waters and soils in different seasons and water phases. Substantial flooding occurred through this study area on July 13, 2012. These high flows modified channels, riparian habitats, deltas, and resulted in significant sediment deposition into Lake Havasu. This particular event was in the upper 10% of those recorded historically and essentially changed the documented baseline conditions. Continued study of the storm water and sediments deposited will lead to a greater understanding of the local watershed and water quality conditions and the potential effect to environment. Project Objective: This agreement would be awarded for a five year period to allow sufficient time to collect data from the infrequent rain events in the Lake Havasu City area. Water and soil samples will be collected and analyzed to understand changes to the lake resulting from floods and to continue to study and document upcoming flood events. The assessment process will include at least 20 sample stations at the mouths (deltas) of these drainage basins. Laboratory analysis for both ground and surface water quality parameters of concern that were highlighted from previous sampling will be the focus at several washes that flow through Lake Havasu City into Lake Havasu. At a minimum, the samples will be analyzed for salinity, nutrients, metals, and pathogens. Actual collection of flood water samples is desired, but not mandatory. In the event that actual floodwater samples are not collected, sub-surface water samples will be collected at the drainage deltas. Assessment and mapping of sediment deposits and patterns at the lake edge will be completed, which include estimates of freshly deposited lake bottom materials in the delta areas. Flood impacted vegetative communities will continue to be assessed to determine potential community shifts. Photo points at the identified wash deltas will continue to be monitored for documenting shoreline changes. Testing of sediments or organisms within these delta formations is desired relative to pollutant accumulation information, or community tolerance of pollutants. A minimum of 100 acres of the delta deposits will continue to be assessed. In addition, soil and water samples will be collected and analyzed to establish baseline concentrations of salinity below the Recreation & Public Purpose lease to Lake Havasu City, known as the Havasu 280. The Havasu 280 is leased to Lake Havasu City for the development of a golf course, community park, and performing arts center and is located adjacent to Lake Havasu and Indian Peak Wash bisects the property. Monitoring salinity levels associated with the development of the Havasu 280 was identified in the environmental assessment for the lease. Data supporting this work will be collected in the field at intervals and periods when there are rain events, which is typically during the summer monsoon and winter rain periods. Findings and recommendations of this third and fourth year study will then be presented in a final report for both City and BLM purposes no later than two years following the date of this agreement. This report will be drafted, finalized and delivered by the primary City investigator in collaboration with the BLM point of contact, with individual copies submitted to respective Managers prior to September 30, 2015.
Office: Bureau of Land Management
ebell@blm.gov
