Despite the recent storms, water storage efforts on the Peninsula underperformed.

Theoretically, the extraordinary series of atmospheric rivers that doused the Central Coast in late December and early January should have been a boon for efforts to divert water from the Carmel River and store it in the Seaside Basin for future use, a mechanism known as aquifer storage and recovery (ASR) – essentially, injecting water into an underground reservoir, where it can then be extracted during dry years.

That has not been the case. Due to a number of factors, those efforts have run up against constraints.

The Monterey Peninsula Water Management District’s ASR program was launched in the 2000s as part of an effort to shore up that water supply, and in 2017 – its record year of performance – it diverted and stored 2,345 acre-feet of water, about one quarter of the Peninsula’s annual water demand.

In a perfect world, MPWMD could divert up to 26 acre-feet per day when the Carmel River is flowing at sufficient levels. But it’s not coming anywhere near that number: During one week in the recent storms, MPWMD was only able to bank about 4 to 5 acre-feet per day.

Here’s why: There are four ASR injection wells in Seaside, two owned by MPWMD – two owned by Cal Am. But this winter, Cal Am hasn’t been using its injection wells for their express purpose. Instead, one of those wells is extracting water from the Seaside Basin and sending water south, now that it has to abide by legal pumping limits, imposed by the state, on the Carmel River. Ideally, Cal Am would have already had extraction wells in place in Seaside, but instead is using one of its injection wells. (Its other injection well is linked, and also not being used for injection.) That means instead of four ASR injection wells functioning this winter, there are only two in operation.

Cal Am spokesperson Josh Stratton says Cal Am is actively pursuing permitting and design for four new extraction wells, but meanwhile, the water being extracted – rather than pumped into the ASR system – is being sent south toward Pacific Grove via the Monterey Pipeline, which was completed in 2018 at a cost of around $57 million. One of the purposes of that pipeline was to send Carmel River water north in the winter (maximizing ASR), and then south to deliver to users during dry months. Instead, Cal Am has only been using that pipeline to send water south toward the population centers Cal Am serves.

There is also the fact that some Cal Am wells in Carmel Valley had to be shut down during the storms due to flooding – which could potentially inundate them with untreated water, or create an electrical shortage – so less water was able to be sent over the hill to Seaside for injection (via the smaller Segunda-Crest pipeline, which travels through Tehama).

So far this year, MPWMD has been able to store just over 400 acre-feet via ASR, far less than its designed potential, and less than 5 percent of the Peninsula’s annual water demand.

This year – which should have been a banner year for ASR – has mostly been a wash.