The progress on implementing floodwater managed aquifer recharge programs (Flood-MAR) reminds me of the economist’s joke, “sure it works in practice, but does it work in theory?” A lot of focus seems to be on trying to refine the technical understanding of recharge, without going with what we already know about aquifer replenishment from decades of applications.

The Department of Water Resources Flood-MAR program recently held a public forum to discuss its research program. I presented a poster (shown above) on the findings of a series of studies we conducted for Sustainable Conservation on the economic and financial considerations for establishing these programs. (I posted about this last February.)

My conclusion from the presentations and the other publications we’ve followed is that the next step is to set up pilots using different institutional set ups and economic incentives. The scientists and engineers can further refine their findings, but we generally know where the soils are better for percolation versus others, and we know that crop productivity won’t fall too much where fields are flooded. The real issues fall into five categories, of which we’ve delved into four in our Floodwater Recharge Memos.

The first is identifying the beneficiaries and the potential magnitude of those benefits. As can be seen in the flow chart above, there many more potential beneficiaries than just the local groundwater users. Some of these benefits require forecast informed reservoir operations (FIRO) to realize those gains through reduced flood control space, increased water supply storage and greater summertime hydropower output. Flood-MAR programs can provide the needed margin of error to lower the risk from FIRO.

The second is finding the funding mechanisms to compensate growers or to build dedicated recharge basins. We prepared a list of potential financing mechanisms linked to the potential beneficiaries. (This list grew out of another study that we prepared for the Delta Protection Commission on feasible options for beneficiary-pays financing.)

The third is determining what type of market incentive transactions mechanisms would work best at attracting the most preferred operations and acreage. I have explored the issues of establishing unusual new markets for a couple of decades, including for water rights transfer and air quality permit trading. It is not a simple case of “declaring markets exist” and then walking away. Managing institutions have important roles in setting up, running and funding any market, and most particularly for those that manage what were “public goods” that individuals and firms were able to use for free. The table above lists the most important considerations in establishing those markets.

The fourth assessing what type of infrastructure investment will produce the most cost-effective recharge. Construction costs (which we evaluated) is one aspect, and impacts on agricultural operations and financial feasibility are other considerations. The chart at the top summarizes the results from comparing several case studies. These will vary by situation, but remarkably, these options appear to cost substantially less than any surface storage projects currently being proposed.

The final institutional issue to be addressed, but not the least important, is determining the extent of rights over floodwaters and aquifers. California state law and regulations are just beginning to grapple with these issues. Certain areas are beginning to assert protection of their existing rights. This issue probably represents the single biggest impediment to these programs before attracting growers to participate.

All of these issues can be addressed in a range of pilot programs which use different variables to test which are likely to be more successful. Scientists and engineers can use these pilots to test for the impacts of different types of water diversion and application. Statistical regression analysis can provide us much of what we know without having to understand the hydrological dynamics. Legal rights can be assessed by providing temporary permits that might be modified as we learn more from the pilots.

Is it time to move forward with local pilot programs? Do we know enough that we can demonstrate the likely benefits? What other aspects should we explore before moving to widespread adoption and implementation?