June 21, 2006 Exceedance Report

We are submitting the formal communication report for the field exceedances reported on June 21, 2006 (see Table 1 below). Over the past several months, the Coalition has been submitting communication report for field exceedances that include similar explanations for potential causes. Much of this report is similar to those submitted in the past with respect to generalized explanations for these exceedances. However, on review of the data that we have collected over the past two years of sampling, the Coalition believes that the analysis of field parameter exceedances could begin to bring reasonable conclusions regarding the nature and causes for the exceedances that have been experienced in the water bodies. With this in mind, we hope that in the near future the Coalition will be able to provide further insight and explanation in our field exceedance communication reports. Please refer to section 2 of this report for details on the upcoming analyses and actions we plan to carry out.

No follow-up monitoring was performed. Dissolved oxygen (DO) exceedances were experienced previously at Grant Line Canal near Calpack and Terminous Tract Drain @ Hwy 12 on sample dates April 27, 2006 and May 16, 2006 respectively. None of the remaining sample sites listed above have experienced DO exceedances previously this year.

The exceedance in pH sampled at Roberts Island Drain along House Rd on June 20, 2006 was the first experienced this year. However, an exceedance measuring 6.43 was experienced during the following irrigation season sampling that recently occurred on August 15, 2006 (included within an exceedance report submitted on August 16, 2006).

Electrical conductivity (EC) exceedances were experienced previously at Grant Line Canal near Calpack on sample dates March 15, 2006 and April 27, 2006, and Roberts Island Drain @ Holt Rd. on sample date May 16, 2006. EC has been a persistent problem throughout the Coalition region, particularly in the Delta.

We have recently collected a set of field measurements for four sites in the Coalition region. Field parameters were measured three times daily for three days to determine the pattern of the values across a short period of time. We reported exceedances from that sampling last week. We will include these as part of our dataset in the analysis described above. We have not yet had a chance to study these data in any detail and therefore cannot provide any conclusions about daily dynamics of field parameters beyond what we hypothesize in the discussions below.

The inability to find explanations for DO exceedances that have been frequent in the Coalition region over the past two years of monitoring is a cause of frustration to the Coalitions. We have hence reviewed our data base and found that there are sufficient data to begin an analysis of recorded field exceedances such as the investigation of the relationship between parameters such as DO and temperature. Clearly, as described below, temperature and elevation (barometric pressure) control dissolved oxygen, but our past calculations suggest that the dissolved oxygen content of the water is far below the maximum percent saturation for specific temperatures therefore indicating that other factors are likely involved. This is the case in the current exceedances as well (see below). We will be examining this and other potential relationships among the field and water chemistry parameters to determine if we can further clarify our hypotheses about causation. This analysis should take no more than two or three weeks and when completed, we will provide the Regional Board with an explanation of the analyses and results.

Control of DO in surface waters is a function of the several factors including flow and reaeration, water temperature, Biological Oxygen Demand (BOD) including Sediment Oxygen Demand (SOD), Chemical Oxygen Demand (COD), and the relative amount of photosynthesis. DO is a nonconserved constituent and can change dramatically across space and time.

Flow

Re-aeration from turbulent flow is a natural method for reaeration of surface waters. Standing water typically does not exchange oxygen in more than a very shallow surface layer and the water usually is depleted of oxygen by other processes.

Water Temperature

It is well known that colder water has a greater ability to retain oxygen. The water may be saturated with oxygen, but at very high temperatures, the amount of oxygen in the water can be very low. The nomogram below relates water temperature, oxygen concentration in parts per million (mg/L) and percent saturation.

BOD and COD

Generally, BOD has a much greater influence on dissolved oxygen than SOD or COD except in unique situations which are not likely relevant to Grant Line Canal . BOD is a function of the respiration that occurs when organic matter enters the water body and is degraded by bacterial action. The respiration of the bacteria can occur in either the water column or the sediment, and can deplete the oxygen in the water column. Organic material can originate from allochthonous inputs (e.g. organic inputs from dairies, Publicly Owned Treatment Works [POTWs], agricultural operations) or autochthonous sources (benthic and water column algal production and decomposition).

Photosynthesis

Unless waters are extremely oligotrophic, DO usually varies diurnally as a function of changes in productivity. During daylight hours, when photosynthesis is occurring, carbon dioxide (CO₂) is fixed as plant material reducing the CO₂ concentration of the water and increasing the DO concentration. At night, respiration is the driving force, resulting in a decrease in DO. Algal productivity is stimulated by nutrient inputs upstream, but nutrient cycling in surface waters is very difficult to quantify.

Identifying a source of a DO exceedance is particularly difficult and the Coalition has chosen to focus first on the identification of causes of low levels of DO. The processes listed above are expected to change over time making tracking sources for past events nearly impossible. Upstream sampling is not an effective method of tracking DO as it is not a conserved constituent and therefore can change dramatically in a water body over a small space and short time. On the other hand, natural and dynamic micro-ecosystems of the water bodies of concern in the Coalition region can be investigated and certain factors analyzed to better understand why DO levels are inadequate. Factors such as low water flow, temperature, and natural or human induced bacteria or algae growth may be significant factors in the levels of DO available in the water body. Low to no flow (measured or estimated 0 to 1.05 cfs) was consistent across the three lowest measurements of DO during this sampling period which occurred at Robert Island Drain along House Rd , Robert Island Drain @ Holt Rd, and Grant Line Canal near Calpack Rd. Water temperatures at these sites were also above ideal conditions, ranging from 19.9°C to 26.7°C. While there is a definite relationship between measured DO and corresponding flow and temperature, there are other factors also involved the relationship (described previously) that make source/cause identification a complex endeavor. For the three sites identified above (that showed lowest DO measurements),, the percent saturation was approximately 20% at Roberts Island along House Road, 30% at the Grant Line Canal site, and 37% at Roberts Island at Holt Road. Flow was measured as 1.05 cfs at Roberts Island along House Road, estimated to be 0-1 cfs at Roberts Island at Holt Road and stagnant at the Grant Line Canal site. Clearly, temperature and flow are not individually completely responsible for the low dissolved oxygen and any interaction between them is difficult to identify at this point. Hopefully, the data analysis we are conducting will allow us to explore more complex interactions among these variables.

As data become available, we will include nutrients in the analysis and the Coalition may be able to gain a better understanding of the DO dynamics in the subwatersheds. However, source identification and remediation will likely remain beyond the ability of the Coalition to obtain.

There are two potential causes of pH outside the range (6.5 – 8.5) specified in the Basin Plan. First, substances with very low or very high pH could have been added to the water or been the result of a spill. However, given the normal buffering capacity of the stream systems in the region, the pH of the contaminant would have to be relatively high or low and would probably have resulted in noticeable fish kills and the death of other biota in the streams. No such kills were observed and consequently, it is unlikely that the pH exceedances were the result of spills or deliberate dumping into the water bodies.

Control of pH in surface waters is a function of the balance between the buffering capacity of the water and the relative amount of photosynthesis. As previously discussed, unless waters are extremely oligotrophic, pH usually varies diurnally. During daylight hours, when photosynthesis is occurring, carbon dioxide is fixed as plant material, reducing the CO₂ concentration of the water and causing a dissociation of the carbonic acid present in the water, and the pH rises. At night, respiration is the driving force, resulting in a decrease in DO, an increase in CO₂ and a decline in pH. In a diurnal cycle, the lowest pH is expected at dawn because CO₂ produced by decomposition and aerobic respiration would have accumulated since the previous dusk. Sampling at Roberts Island Drain along House Rd. occurred at 8:50 am which is early enough in daylight hours to still show effectively low pH due to decomposition and aerobic respiration as discussed above.

Because of the dynamic nature of pH in water, identifying a the source of exceedances is particularly difficult and it is unclear how it could be accomplished. Most likely, the exceedance is a function of instream and landscape processes that interact to control pH. These processes are expected to change over time making tracking sources for past events nearly impossible. For example, benthic algae are primarily responsible for the photosynthesis that occurs in small surface water bodies. The amount of benthic algae, particularly but limited to filamentous algae, that can build up at a site is a function of the substrate and the flow. As an alga grows, it becomes heavy and is capable of being captured by the current in the stream. When the flow generates sufficient shear stress on the alga, it is sheared off and moves downstream being broken up as it moves. This process of growth and shearing may occur several times over the summer depending on the nutrient inputs and the flow. If flows vary as a result of irrigation return flows or runoff events, the cycle may be very rapid. If the flows are reduced, sufficient shear stress may not be developed and the alga will remain in place for a longer period of time. As flows change and the wetted surface area of the stream changes, the locations of alga growth can change as well. As explained, since pH is a function of diurnal changes in photosynthesis, the exceedance may be solely a result of the timing of the measurement.

The position of the coalition is that the exceedances in the Delta are a function of the source water quality of the Delta waters (see below). During the winter, there are two sources for water found in the drain and irrigation canals of the Delta Islands . Depending on the elevation of the island surface relative to the waters of the Delta channels, hydrostatic pressure may force water into the Delta islands where it collects in the channels and is eventually pumped back into the Delta channels. Rainfall is the second source of water in the drain and irrigation canals of the Delta Islands . This water would dilute the Delta source water that is pushed into the islands. However, since the source water in the Delta is high in EC, water in the drain and irrigation canals within the Delta Islands will also be high in EC.

The Coalition water bodies which rely on San Joaquin River or Delta water have a determined source of elevated levels of EC which are not related to agricultural activities in the area. High levels of salinity have been noticed in this region and are a result of CVP operations that dump a calculated 800,000 tons of salt into the San Joaquin River each year. As stated by the SWRCB, “the actions of the CVP are the principal cause of the salinity concentrations exceeding the objectives at Vernalis” (Revised Water Right Decision 1641 in the matter of Implementation of Water Quality Objectives for the San Francisco Bay/Sacramento-San Joaquin Delta Estuary, Adopted December 29, 1999, Revised March 15, 2000 in accordance with Order WR 2000-02, hereafter referred to as D-1641, see D-1641 @ page 89). The stated high salinity is due to decreased flow of the San Joaquin River as a result of CVP operations and the subsequent delivery of exported water, which by that time has become highly saline, to the west side of the San Joaquin Valley where it eventually drains back into the San Joaquin River. Such a series of reduced flows and drainages, has generated high concentrations and massive loads of salt that have changed the composition of the San Joaquin River .

Consequently, the SWRCB has directed the Central Valley Regional Board to promptly “develop and adopt salinity objectives and a program of implementation for the main stem of the San Joaquin River upstream of Vernalis” (see D-1641 @ page 85). In addition, the San Joaquin River and Southern Delta have been listed as impaired waterways for salinity (EC) under the Clean Water Act and, as a result, is subject to Total Maximum Daily Load requirements to address upstream salinity loads. The TMDL process does not seek to limit loading or concentrations downstream of Vernalis, and gives the applicable parties upstream of Vernalis a number of years to implement the necessary actions.

The Coalition is in the process of developing a study to confirm that the water in the Delta irrigation and drain canals is Delta source water and that irrigated agriculture does not degrade the quality of that water with respect to EC. It appears now that mercury is present in the source waters and may be a problem with the isotopic analysis. That will require a different machine but will still be possible. We can now finalize the design of the study and submit to the Regional Board for review.

Provided the results of the proposed study indicate that the source of the EC exceedances are a result of source water in the Delta, the Coalition anticipates taking no action at this time with regard to testing results which indicate EC levels are above existing water quality objectives.

Complete analytical results are attached electronically to this communication report in the form of the field sheets in pdf format.

4. Time schedule to identify and implement the Management Practice Effectiveness evaluation.

At this time, it is not possible to implement management practices to address DO. We will continue to monitor DO to detect any patterns in exceedances that might be present. Additionally, the analysis of the dissolved oxygen data as described in previous sections may provide us with some insight into causation.

At this time, it is not possible to implement management practices to address pH. This is the first exceedance of pH at the Roberts Island Drain along House Rd. site, and we will continue to monitor pH to detect any patterns in exceedances that might be present. As with DO, we are engaged in data analysis that may provide some insight into causation.

After conducting a study later this year that will help us to determine the source(s) of EC (i.e. source of salts in the surface waters), we will better be able to address the proper implementation of management practices. We will file an addendum to this Communication Report with the results of the study and management plans, if any, that are to be implemented in the watershed.

Action	Anticipated Completion Date
Proposed EC Isotopic Study to Identify Potential Sources	December 31, 2006

Pending the results of the proposed study this summer, no management practices effectiveness evaluation is planned. If the results indicate that the EC exceedances are a function of agricultural practices, we will provide an amendment to this Communication Report with a time schedule for implementation of management practices. The time schedule will be based on the current submission, and all contacts with growers and outreach will occur as if the process was initiated at this time.