Grassland Water District Role Play Your Role: Water Managers of the Grassland Water District Instructions: 1)Read the following background information about the Grassland Water District and its importance to the region. 2)Next, work in teams to identify factors that move the water in or out of your District. Think of “process” in a systems approach in a mass balance context for water in wetlands. These factors relate to the creation of a wetland model. 3)Then, Share-out with the class the factors your team thought might be apart of a mathematical model made to represent how water moves in the Grassland Water District system of wetlands. Hint: Use your wetland model background knowledge we have been building upon this past week to strengthen your team’s brainstorm. 4)Lastly, we will compile a class brainstorm and compare it with the real mathematical model (WETMANSIM) that has been used in the District.

Grassland Resource Conservation District The Grassland Resource Conservation District contains approximately 75,000 acres and is composed of privately-owned hunting clubs and other privately-owned wetland areas, as well as all or portions of several state wildlife areas (such as Volta WA, Los Banos WA, Mud Slough Unit, Gadwall Unit, and Salt Slough Unit) and federal wildlife refuges (such as Kesterson NWR, San Luis NWR, Freitas Unit, and Blue Goose Unit). The area is the largest contiguous block of wetlands remaining in California’s Central Valley and is a major wintering ground for migratory waterfowl and shorebirds of the Pacific Flyway. Up to 30 percent of the Central Valley’s wintering population of ducks use this area, which is located in the San Joaquin Valley in Merced County. The U.S. Fish & Wildlife Service (USFWS) ranks the habitat provided by the GRCD as the most important complex of wetlands in the San Joaquin Valley. The wetlands of the GRCD are a component of the Western Hemisphere Shorebird Reserve Network and are internationally recognized for their importance to shorebirds (Bureau of Reclamation,1992). Lands within the GRCD are primarily managed for waterfowl habitat. The Grassland Water District (GWD) has a Water Management Plan, but no overall habitat management plan exists for the GRCD because of the large number of individual property owners. The management objectives of the GRCD include an active program to encourage natural food plant production (such as swamp timothy, smartweed, and wildlife millet) and habitat protection. Land uses include seasonally flooded wetlands, moist soil impoundments, permanent wetland, irrigated pasture, and croplands.

Grassland Resource Conservation District (continued) The GRCD contains most of the 51,530 acre GWD. The GWD is a legal entity that was established under section of the California Water Code to receive and distribute CVP water. The GWD delivers CVP water to the wetland areas within its boundaries. The GWD contains approximately 165 separate ownerships, most of which are duck clubs. Perpetual easements have been purchased by the USFWS to help preserve wetland-dependant migratory bird habitat on approximately 31,000 acres serviced by the GWD. These easements authorize the USFWS to restrict land uses that would diminish wetland habitat values.

Flood-up Map of the Grasslands Water District (South)

Compare Class with Model Class CollaborationWETMANSIM Model

Compare Class with Model Class CollaborationWETMANSIM Model Evapo-transpiration (ET) Porosity Fillable Vadose Zone Porosity Seepage Water Added from District Runoff Electrical Conductivity (EC) a.k.a. Salt Ultimately Model Calculates: Total Wetland discharge (acre-ft) TDS wetland discharge (mg/l) Wetland discharge salt load (tons/day)