While Pasadena was working for new water from the San Gabriel River and the Colorado River during the 1930s, local groundwater levels continued to fall. Raymond Basin pumpers, motivated by the steadily increasing population and improved pumping technology, persistently drew water from the groundwater basin without fully understanding the effects of their actions on each other and on the basin.
The first water wells in Pasadena had been drilled way back in 1881 at the southern end of the city where the Raymond Hotel, a renowned resort, was located. Early residents saw ancient springs and water gushing to the surface in artesian wells, but they did not understand the relationship between those phenomena and the Raymond Dyke or earthquake fault that lined the lower limits of the city. Limited by the science of that era, they had only a primitive understanding of the nature of the Raymond Basin, the 40-square-mile groundwater basin or aquifer beneath Pasadena and surrounding communities.
Groundwater hydrology or hydrogeology was a science in its infancy, and the Raymond Basin provided many invaluable lessons to that emerging science. It took many decades to understand the nature of the groundwater basin and how to manage it.
The Raymond Basin is like a massive bowl of sand and gravel that is filled up by the flows of the Arroyo Seco coming from the upper watershed in the San Gabriel Mountains and by rainfall from throughout the watershed that slowly seeps into the ground. The rich alluvial soils in the foothills are like a sponge soaking up rainfall and percolating it into the aquifer. But the buildings, roads and paving that came with urban and suburban development reduced the ability of the earth to capture the steam flow and rainfall. New advances in pumping technology made it too easy to drain the basin without considering the longterm significance of destroying such a valuable natural resource.
By the turn of the 20th century, there were 140 hydraulic wells pumping water from the Raymond Basin. In 1914 the new Pasadena Water Department tried to alleviate the falling groundwater levels they observed by spreading the stream flow of the Arroyo Seco water on the sandy soils near the San Gabriel Mountains to replenish the groundwater. Groundwater levels, however, continued to decline. The first full description of Raymond Basin’s geology and underground water storage characteristics was not completed until 1934, and the findings were ominous. They documented a consistent drawdown of the basin for more than two decades.
In 1935 Pasadena officials called together all the entities that were pumping from the Raymond Basin, including local communities, small private water companies and large institutional water users like the Huntington Library and Mountain View Cemetery, in an attempt to reduce pumping to a sustainable level, but this effort was not successful. Pasadena realized that all the pumpers, including Pasadena, shared in the problem and that all should share in the solution, but found little cooperation from its neighbors because there was not yet a legal framework for determining water rights in the aquifer. Two years later Pasadena initiated legal proceedings against Alhambra and other major Raymond Basin water users. The City of Pasadena v. City of Alhambra et al. lawsuit sought to legally divide or adjudicate water rights in the basin and to end the annual overdraft or drawdown of groundwater.
Superior Court Judge Frank Collier called for a detailed geological study of the groundwater basin to determine its characteristics and capacity. Distinguished Caltech geologist John Buwalda conducted that study. The California Division of Water Resources played the role of referee, verifying the data and conclusions. The study, an early milestone in groundwater modeling, indicated that the safe yield of the basin was 21,000 acre feet per year, but that pumpers were drawing out 29,000 acre feet, more than a third too much.
In 1943 after an extensive investigation of the usage and “safe yield” of the Raymond Basin, all but one of the 20 parties involved in the action agreed to a stipulation that included: 1) an admission that taking water was adverse to the claims of other parties; 2) allocation of the basin’s safe yield; 3) the declaration and protection of each party’s rights; and 4) an arrangement for the exchange of pumping rights among parties. The historic agreement was based on a process called mutual prescription. Instead of honoring only senior water rights and cutting off pumpers with more recent claims, as was often done throughout the US, each party agreed to reduce its annual pumping and take a set percentage of the Basin’s safe yield. Judge Collier determined that each party had a“present unadjusted right,” defined as the highest amount of water continuously produced during a five year period prior to the filing of the lawsuit. Each party owned this right by “prescription” or longstanding use, and the rights were of equal priority. Judge Collier then defined a “decreed right” for each party, which was that party’s present unadjusted right adjusted downward about one-third so that the sum of all parties’ decreed rights matched the estimated safe or sustainable yield of the basin.
On December 23, 1944 Judge Collier signed the judgment adopting the stipulated agreement worked out by the parties. The California Department of Water Resources became the watermaster for the basin, charged with policing the adjudication. In 1949 the California Supreme Court affirmed Pasadena v. Alhambra. The decision validated mutual prescription as a basis for establishing water rights and resolving groundwater management problems.
The Raymond Basin Adjudication that resulted from City of Pasadena v. City of Alhambra et al. was the first groundwater adjudication or division of water rights in California and the first to use the California Division of Water Resources to determine water rights. The agreement still provides the framework for the management of local groundwater supplies. A major advance in the science and governance of groundwater basins, it has been praised as an exemplary model of cooperative self-government.
In 1955 at the insistence of the pumpers, the estimated safe yield was adjusted to 30,622 acre-feet, more than the historic level. In 1984 the Raymond Basin Management Board, made up of representatives of the local parties, assumed watermaster responsibilities for managing the basin. The Raymond Basin Management Board (RBMB) has been a cooperative mechanism for local management of groundwater resources, while retaining the safe yield concept of the original adjudication.
In the early 1990s, the RBMB established long term storage policies and allocated storage capacity to the basin parties, an important step in allowing all parties to benefit from the storage potential of the basin and improving the management of local water resources. In 1992 Pasadena Water installed facilities for injecting and spreading imported water in the local groundwater basin to augment its replenishment activities.
In 2007 a study commissioned by the Raymond Basin Management Board found that in the main part of the Raymond Basin groundwater production has been greater than net recharge from rainfall, causing lower groundwater levels and increased pumping costs. To remedy this, Raymond Basin pumpers in the main basin agreed to reduce their pumping allocation by thirty percent over a five year period. Pasadena’s allocation was reduced by 417 acre feet in 2009 and was reduced by a similar amount each year until 2014.
This article, written by Tim Brick, was part of "Pasadena Water — the Essential Ingredient, Celebrating 100 Years of Municipal Service" published in 2012.