Water Quality Addressed

 

Last updated 6/18/2019 at 1:58pm



While residents of Borrego Springs all want a sufficient quantity of water to sustain our personal and recreational needs, currently available from our sole source – groundwater pumped from the nearly-100 square mile aquifer beneath us – we also do not want to sacrifice quality over quantity. We want to be able to drink our groundwater and know it’s safe.

The Draft Groundwater Sustainability Plan (the Plan) is currently out for a 60-day period of public review and feedback, and following County Supervisor and State approval, it will be adopted by our County-BWD umbrella organization known as the Groundwater Sustainability Agency (GSA). After adoption of the Plan, the 20-year quest (at almost $20 million) for sustainability via specific management/administrative and project actions will begin.

Within the Draft GSP are water quality-related goals, standards, objectives, and operational strategies within which Water Quality (WQ) criteria are evaluated according to Sustainable Management Criteria under the following headings: 1) Undesirable Results; 2) Minimum Thresholds; and 3) Measurable Objectives.


Undesirable results are defined as significant and unreasonable degraded water quality. Degraded water quality is, according to the Plan, related to the sustainability indicators including chronic lowering of groundwater levels to below the Upper Aquifer and reduction in groundwater storage. “Portions of the Subbasin are also experiencing, or are under threat of experiencing, degraded water quality,” the Plan states.

“In general, the groundwater quality in the Subbasin meets California drinking water maximum contaminant levels without the need for treatment.” Up till now, anyway. As the aquifer level lowers over the 20-year Plan life, it could reveal harmful concentrations of contaminants requiring dilution or a treatment facility.

Minimum Thresholds – The Plan will gather data and use certain criteria to justify minimum thresholds for water quality. It’s a quantitative exercise, so sufficient data is required.

“The minimum threshold for degraded water quality is protective of existing and potential beneficial (and overlying) uses and users in the Subbasin,” the Plan states. For contaminated single wells, “Alternative means of addressing degraded water quality such as wellhead treatment may also be technically and financially achievable.” The goal for municipal and domestic wells is to meet well-established State drinking water standards under Title 22.


Measurable Objectives – Let’s first look at the GSP’s Sustainability Goal in reference to water quality. “Conditions within the Subbasin will be considered sustainable when the following sustainability goals are met: 1) Groundwater quality, as measured in municipal and domestic water wells, generally exhibits a stable and/or improving trend (my emphasis) for identified contaminants of concern (COC’s); and 2) Groundwater quality is suitable for existing and future beneficial uses.”

“Analyzing trends,” according to local resident and hydrogeologist John Peterson, “is a four-dimensional exercise.”

Peterson has spent over 30 years in County government and as a private consultant shouting from the rooftops about establishing a reliable water quality monitoring network for Borrego Springs, and now his time-dependent concerns over lack of sufficient data is being officially addressed by means of the GSP.

The Plan speaks to a Project & Management Action for Water Quality Optimization (PMA-5) as follows: “The Water Quality Optimization program is intended to identify as-needed direct and indirect treatment options for BWD to optimize groundwater quality and its use and minimize the need for expensive BWD water treatment to meet drinking water standards.”

Peterson insists that we need to know the aquifer layout, in three dimensions, and conditions over time ( such as the nature and extent of a plume of contaminated groundwater moving slowly towards a municipal well).

“We don’t have that yet,” Peterson said. “It will take years of data gathering” to accurately model whatever trend(s) is/are apparent. The first five-year milestone report, in 2026, would be the first opportunity when data, and its analysis, might provide a picture with some degree of accuracy of then-current conditions and future trends.


Monitoring Network – “The monitoring network is designed to collect sufficient data to demonstrate short-term, seasonal, and long-term trends in groundwater and related surface conditions, and provide representative information about Subbasin-wide groundwater conditions as necessary to evaluate Plan implementation. The most critical sustainability criteria to be monitored directly for the Subbasin are chronic lowering of groundwater levels and degraded water quality at the key indicator wells” (my emphasis). We therefore, once again, need lots of data to accurately identify problems and options.

The issue arises as to adequacy of future water quality monitoring to obtain “measurable objectives,” which will hopefully be addressed over time under the auspices of the GSP.

Currently, only one BWD well (ID 1 – 4) out of the three “key monitoring wells” (see Graphic) proposed for gathering water quality data lies in the Northern Management Area (NMA).

It is located several miles south and west of the citrus farms, where there is the most intensive use of nitrates. Nitrates are a contaminant “trending” upwards, according to the GSP. Additional wells are needed nearer to Coyote Canyon, our principal aquifer recharge source.

Contaminant “trends,” while showing unchanged in all but three categories (nitrates up in NMA, sulfates down in NMA and SMA ), are currently reliant upon a bare minimum of data.

A cursory look at one Plan graphic (included in our graphic) shows “aquifer saturation” at a bare minimum in a large area of the NMA, and 0% in a fairly large section where concentrations of potential chemical contaminants that could be detected are not being diluted, as would be the case if soils were saturated.

If present, they’ve been filtering down into the aquifer at nearly full strength. Where are they headed? To the Borrego Sink? Migrating toward municipal water supplies? Unknown. It’s clear, however, at least through the eyes of Peterson, that “more monitoring wells generating much more data are called for in the NMA.”

Monitoring wells are administered by BWD, but reliable data could also be provided by “other” pumpers. The matter of how much and how often water quality monitoring data from “other” pumpers will be generated and reported is still up in the air. Again, we need data, lots of it, and we need it from enough “key monitoring well” sources, and over a sufficient time period, to make heads or tails of trends versus anomalies in the data.

Which chemical contaminants will be tested? Arsenic, nitrate, sulfate, and Total Dissolved Solids – TDS. Let’s talk arsenic. According to the Plan: “Water quality results indicate that there is elevated arsenic detected at concentrations above drinking water standards in the lower aquifer of the (South Management Area).

As the occurrence of wells screened in discrete aquifer zones is limited, especially for the lower aquifer in the NMA and CMA, it is uncertain if elevated arsenic occurs at depth in these areas of the Subbasin.” Perhaps it’s a good idea to find out for certain.

What are the procedures for WQ Testing? At some point in time down the road, there have to be a sufficient number of wells to gather sufficient and statistically significant data. Until then, the GSP will require:

“Prior to sampling, the sampler must contact the selected California-certified environmental laboratory to schedule laboratory time, obtain appropriate sample containers, and clarify any sample holding times or sample preservation requirements; Each well used for groundwater quality monitoring must have a unique identifier; Groundwater elevation will be measured in the well following appropriate protocols, as described above; General well specifications for the wells to be sampled should be available in the field; Sample containers will be labeled prior to sample collection; Samples will be collected under laminar flow conditions – laminar flow occurs when fluid flows in parallel layers, with limited lateral disruption or mixing of the layers; All field instruments will be calibrated daily and evaluated for drift throughout the day; All samples requiring preservation must be preserved as soon as practically possible, ideally at the time of sample collection. Samples to be analyzed for metals (i.e., arsenic) will be field-filtered prior to preservation; and finally, if pumping during sampling or purging causes a well to go dry, the condition will be documented and the well will be allowed to recovery to within 90% of the original level measured prior to pumping.”

How much will it cost? Within a FY2020 – 2040 Total GSP Operations and Monitoring budget of $669,000 dollars ($700K), semi-annual WQ monitoring and operations costs are estimated to run about $69K, or about 10% of the total Operations and Monitoring budget. The WQ-related costs will rise each year as Program Management Actions move toward full implementation.

The total $19.1 million estimated budget over the 20-year GSP implementation period is exclusive of capital construction costs for specific projects, for example new wells (~$1.5 million per well) or specific PMA action items are required.

 
 

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