Recharge Toolkit: groundwater recharge explained with California's public data

Recharge is the part of groundwater management that districts and GSAs most often have to explain: to boards deciding priorities, to growers asked to take water in winter, to legislators and county supervisors weighing funding, and to reporters covering SGMA. The explanation draws on public data spread across USGS, DWR, the State Water Board, and UC Davis, and most of it has never been put in one place in a form a non-specialist can follow. These four tools do that.

Recharge Hub

Explain how recharge works and where it fits.

A primer that walks a reader from how an aquifer carries dry years to what recharge costs and how it gets permitted, with a map that shows soil suitability, DWR recharge potential, subsidence, and basin boundaries on one screen.

Use it for board orientation, grower meetings, staff onboarding, and the background section of a funding request. Prints as a document. Soil suitability and basin boundaries cover the state; the DWR recharge-potential and subsidence layers follow DWR's published coverage.

Open the hub

90/20 Eligibility Tool

Show what winter water availability looks like.

Daily streamflow at 328 USGS gauges against the State Water Board's streamlined method, with each gauge's record of winter days above the threshold.

Use it to explain to a board or a grower group why the diversion window matters, how much of a winter typically qualifies at a nearby gauge, and what this winter is doing once the window opens December 1.

Open the tool

Refreshed every morning.

Groundwater Map

Show the basin, the GSA, and how the pieces connect.

GSAs, Bulletin 118 basins, SGMA priority, counties, irrigation districts, reservoirs, and the CVP and SWP conveyance on one map, with a view isolating the sixteen San Joaquin Valley subbasins the Unified Water Plan was built from.

Use it to orient new board members, illustrate a partnership or coalition, and give legislators and county supervisors a picture of where a district sits.

Open the map

Merced River Availability

Show what a diversion point looks like on paper.

A worked example on one river system: click any point on the Merced network and see the threshold, days above it during the window, the allowable rate, downstream demand, and the winter record.

Use it to teach what a streamlined water availability assessment contains and to illustrate the same idea for another river.

Open the example

If a chart, map, or explanation here would help your district or GSA tell its recharge story to a board, a legislator, or a community, use it. Requests for other rivers, basins, and audiences are welcome.