BAY DELTA SCIENCE CONFERENCE: A Review of Water Quality Science in the Delta: Chemical contaminants and nutrients

As part of its charge to review science activities that support adaptive management in the Delta, the Delta Independent Science Board (DISB) has completed a review of the scientific basis for assessing water quality in the Delta.  The review focused on chemical contaminants and nutrients and assessing how water quality information is being used in management decisions, especially for  supporting adaptive management.   The DISB has published the review, which has four main findings, along with ten general findings that are accompanied by specific recommendations.

At the 2018 Bay Delta Science Conference, Dr. Tracy Collier gave a presentation summarizing the findings and recommendations.

Dr. Tracy Collier began by noting that the Delta Independent Science Board is statutorily charged in the Delta Reform Act with conducting reviews of science underlying adaptive management and general management of the Delta.  The DISB has approached this thematically, so rather than reviewing individual programs, they reviewing themes.  The DISB has completed several thematic reviews in the past year, such as adaptive management and Delta as an evolving place.  The review of water quality science in the Delta was completed in July of 2018.

As in the previous reviews, the DISB does a variety of information gathering, including literature reviews, distribute questionnaires, conduct in-person reviews, and release drafts for public comment and use that to finalize the review.

There has been a lot of interest in what we’re going to do about water quality in the Delta, and what the proposals for more northerly diversions might do to water quality,” he said.  “So we have approached this review to try to look at that big picture water quality but we really had to focus it on chemical contaminants and nutrients, which is why we initially call this part 1, because so many people obviously on water quality expect many things other than chemical contaminants and nutrients.”

There were four main findings from the review:

(1) It is not clear whether water quality data are sufficient to support management decisions and policies, nor is it clear how water quality data are being used by managers;

(2) Adaptive management is rarely built into water quality programs; but Dr. Collier said that this can be said about virtually everything going on in the Delta.  “Adaptive management is the mantra that we’re all supposed to be adhering to and utilizing,” he said.  “It’s a very difficult problem, so it’s not at all a surprise that adaptive management is not being widely used in water quality programs.”

(3) Water quality too rarely enters into discussions about water supply and reliability;

(4) Although several entities in the Delta fund research and monitoring activities aimed at protecting water quality in the Delta, these resources tend to support specific compliance needs.

Dr. Collier than discussed some of the other findings and recommendations.

He presented a slide with a word cloud of the top 40 words from the report, acknowledging that water quality is a confusing subject for people to talk about.

“People come at it from many different angles; they have different viewpoints and different backgrounds, so our finding was that there is little that is simple and much that can be misconstrued about water quality in the Delta,” he said.  “The recommendation is that we really need to figure out how to promote a shared understanding of water quality in the Delta through the development and use of both conceptual models that let you understand where everybody else is coming from as well as numerical models.”

There is still a lot of uncertainty about the effects of nutrients and some contaminants on the Delta ecosystem, especially those of emerging concern.  Blue-green algae blooms in freshwater are becoming an increasing problem in the Delta and elsewhere, and the question of nutrients and how they contribute to that is obviously one of a lot of current interest, he said.  “Our recommendation is that the management of chemicals of emerging concern and harmful algal blooms requires greater vigilance and coordination between agencies to protect both ecosystem health and drinking water safety.”

The ecosystem health aspects of water quality and drinking water quality have some overlaps but in many cases, they are very different issues,” he added.

Dr. Collier next presented a slide with some graphs from work done by Stephanie Fong a few years ago that shows the strong correlations between applications of pyrethroids in the Delta and declines in POD (Pelagic Organism Decline) species.  He noted that these graphs represent two species, but the work showed similar declines for four species.

There were stronger correlations with pyrethroid applications than were found with some of the indications of flow,” he said.  “So this work along with a lot of other data that have been developed both in the Delta and in other ecosystems, we do know that some chemical contaminants, including certain pesticides, mercury, and selenium, are having deleterious effects on the health of organisms in the Delta.  It requires more study, it requires more information, but we do know there are deleterious effects occurring.  With pesticides, we are much more able to twist that knob to do something about it than we are with selenium and mercury.

The recommendation is that we need to further assess the effects of chemical contaminants on the Delta ecosystem through holistic studies that combine toxicity testing and chemical analyses with fish and food-web monitoring.  There has not been much attention paid to interactions among chemical contaminants as well as the interactions between chemicals and other stressors.  “It’s not easy to do but we really have to approach it as not a simple dose-response relationship,” he said.

He next presented a slide with a conceptual model that illustrates how pesticides and metals and nutrients and other aspects of water quality all should be considered in how they interact with each other and how it can affect ecosystems.

We need to do studies that look at the interactions between chemical contaminants,” he said.  “Are contaminants acting antagonistically, synergistically, additively, as well as other stressors in combination with chemical contaminants?  We need to better understand how these multiple chemicals affect the ecosystem in the Delta.”

Dr. Collier then presented a slide from work he did with NOAA many years ago.  Along the bottom are two groups of fish, one fed chemical contaminants that are equivalent to what we find in their stomach contents in the field, and the other fed only controlled food, and looking at mortality on this axis, they did not see any difference in mortality of the fish fed the contaminants versus those not fed contaminants, he said.

But when we take this same group of fish and expose them to a pathogen that they are going to encounter when they enter the ocean, such as salmon do when they move from fresh water into saltwater and encounter saltwater pathogens, and now we find that fish with the contaminants, the upper curve, are dying faster than the fish without the contaminants,” he said.  “So if you just focus on the contaminant exposure, you won’t see a difference necessarily in the outcome, which was in this case, mortality.  But if you add other stressors, you can in fact show that difference.”

Another finding was that studies that emphasized broad questions about interactions between nutrients, food webs, and ecosystem processes are going to better serve management needs, especially compared to narrow research on nutrient forms and their ratios, which is the approach that has been taken in the past.  “The recommendation is that we need more research on the effects of nutrients on the food web and on the growth of aquatic weeds,” he said.

On the aquatic weeds issue, one of the questions we raised is we have the aquatic weed issues and we largely manage them with herbicide applications, but when we put the herbicides out there, what is that going to do to the primary productivity of the phytoplankton because we have applied an herbicide,” he said.  “We also take those weeds and treat them in place, and their nutrients can be rereleased back into the surface waters.  We know the issue of primary productivity in a big issue in the Delta, so what is this sort of weed control doing to the overall balance of primary productivity?

The effect of spraying herbicides for aquatic weed control is a question that has been outstanding for several years in the Delta, but Dr. Collier said that recently there has been more focus on it.  “The Department of Water Resources and the Division of Boating and Waterways have come together with others and they are doing some good research that’s going to help us get a handle on what kind of approach this is and whether it’s the best approach,” he said.  “It’s definitely more cost effective than things like physical removal.”

There is no comprehensive contaminants monitoring and assessment program in the Delta, he said.  “The Delta RMP is a new program, but it’s coverage is not sufficient to satisfy the need for information that they are being asked.  The recommendation is that the Delta RMP needs to expand the contaminants it monitors, and increase the temporal and spatial coverage of its measurements.”

He presented a slide with a list of a number of different agencies that they talked to for their review; he noted there were others.  “What we found was that the collaboration among agencies conducting monitoring in the Delta on these water quality issues is neither systemic nor is it well organized, and the recommendation is improved collaboration between agencies that would lead to better linkages between the water quality monitoring that’s being done for compliance and monitoring being done for special studies and research.”

Water quality monitoring is often not done at frequencies commensurate with the variability of the contaminants, he said, acknowledging that chemical analysis can be expensive and it’s hard to get the temporal and spatial density that is needed.  “But we do really need to have a better understanding of the spatial and temporal variability of the contaminant delivery and the role of key events like the first flush tides, and how do these things affect contaminant loadings, contaminant levels, and how does that in turn potentially affect ecosystem processes,” Dr. Collier said.

He noted that the California Water Quality Monitoring Council can be critically important in making monitoring data available, but not everyone they spoke with had heard of them and their mission.  “So we said that they really do need more resources and authority to be more effective.  Other agencies can contribute to that mission; it doesn’t have to all go through them.”

Data management efforts do not match the complexity and growing magnitude of water quality monitoring, assessment, and management issues in the Delta, and the obvious recommendation is that data management efforts need to be improved.  He acknowledged that there is a state effort to make data more available, but there are still many questions about quality assurance and quality control, so everyone needs to maintain their efforts.

Dr. Collier then gave his concluding thoughts.  “We are currently undertaking a review of the monitoring enterprise writ large in the Delta,” he said.  “What I’ve just presented are our recommendations that are really related to monitoring issues of water quality constituents, but this is going to really inform our monitoring enterprise review as well.   This clearly points to the need to document and evaluate the components of water quality monitoring in the Delta.  It’s very hard to get a handle on who is doing what and where, when and there the information is.  This review should help prioritize water quality research.”

Dr. Collier said that although it wasn’t discussed much in the review, it was brought up in public comments and the board’s own internal discussions that while their recommendations focus on a better understanding the effects of water quality on the ecosystem and on drinking water, we do really need to keep working on source reduction.  “Source reduction is probably the most cost-effective way to reduce impacts of water quality constituents on ecosystems and we really need to look at source reduction and better ways to achieve a reduction,” he said.

Dr. Collier ended by noting that the Sacramento Regional County Sanitation District is undertaking a major upgrade of the Sacramento Regional Wastewater Treatment Plant.  “The commitment to further reduce nutrient loadings is an excellent example of regional efforts to address water quality concerns in the Delta,” he said.


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