Review of the Draft Federal Long-Term Monitoring Plan for the Colorado River below Glen Canyon Dam (1994)

The introduction of the long-term monitoring plan gives a rationale by which expenditures on environmental monitoring might ultimately be determined. Factors to be considered include availability of funds, priorities for components of monitoring, and costs that are derived from contracting procedures (i.e., bids). The NRC committee disagrees with this rationale. The minimum monitoring requirements for the Grand Canyon are legitimately determined by needs for basic information. The present wording of the plan might suggest that the plan subordinate long-term monitoring to the availability of money. This is inappropriate in view of the significance of sound monitoring information for the protection of environmental resources in the Grand Canyon. Similarly, the monitoring plan should avoid stating that the cost of long-term monitoring is dependent on priorities that are assigned to the components of monitoring. This begs the question of responsibility for the assignment of priorities. The plan should assign priorities explicitly. Finally, deference of the plan to the outcome of bidding is unnecessary. The GCES program personnel, having expended millions of dollars on environmental studies similar to those being recommended here, should be in a position to estimate at least a range of costs for specific kinds of environmental monitoring.

The introduction refers to “interests.” Similar references appear in other sections of this report. From the context, it appears that this is a reference to individuals, or groups of individuals, who have an interest in the operation of the Dam or the resources that might be affected by operations of the Dam. The meaning of this term needs to be explained more clearly.

The opening paragraph stating the purpose of monitoring is concise, but not entirely clear. For example, is it true that one purpose of monitoring will be to study the “implementation” (as opposed to the effects) of a decision? This needs to be explained. Each of the items that are listed as purposes should be reviewed for clarity. The references to “attributes,” “project impacts” and “model efficacy” are particularly unclear.

This section of the monitoring plan also makes reference to adaptive management. Adaptive management will undoubtedly be described in the DEIS, of which this monitoring plan will be a part. However, it is also likely that the monitoring plan will be used separately from the DEIS. For this reason, it is important for the monitoring plan to explain the meaning of adaptive management as it applies to the operation of Glen Canyon Dam. The plan gives one paragraph of explanation, but this paragraph is not sufficiently clear. For example, it is not clear what the “goals” of the DEIS would be. The DEIS will presumably give a preferred alternative, and the Record of Decision (ROD) may specify that the Dam will be operated according to the preferred alternative. How does adaptive management fit into this framework? Will operations stray outside the boundaries of the preferred alternative, or is adaptive management merely a way of making minor adjustments within the framework of the preferred alternative?

The last paragraph of the section on purposes of monitoring explains the conceptual basis for defining the geographic scope of monitoring. This is an important section, and it comes across clearly and reasonably.

The long-term monitoring plan explains some differences between monitoring and research. This is necessary because the purposes of monitoring and research are frequently confused. Although the plan recommends research, it is not very specific in doing so. The committee believes that the long-term monitoring plan should specifically request support for long-term research that would be complementary to monitoring. Monitoring will probably demonstrate unexpected trends, and management should be in a position to support research that will demonstrate why monitoring has produced unexpected results. Some examples of research that could be included in the plan are: (1) research that would improve understanding of water flow, sediment transport, or biotic resources; (2) research that would lead to reduction of the cost of monitoring; and (3) research that would demonstrate the effects of operations on specific environmental components. In the absence of any specific recommendations, the prognosis for research is poor. It will prove difficult to allocate money for research that is not requested by experts.

The opening segment of the section on philosophy for monitoring explains the necessity for collection of data on a wide variety of environmental variables. The rationale here is sound, and reflects the spirit of the NRC's 1992 workshop on long-term monitoring.

The plan lists a number of “attributes” that should be included in the long-term monitoring plan. Some of these seem vague and difficult to interpret. For example, what is “area and species composition of a riparian habitat for associated vertebrates and invertebrates?” (page A-3, number 5 of the plan) Is the species composition that of the plants, the vertebrates, the invertebrates, or all of these? Also, there appear to be some obvious omissions from the list of items to be monitored. For example, backwaters are considered to be critical habitat for some elements of the aquatic biota, and yet they are not specifically listed for monitoring. The section on sediment dynamics does not list measurement of sediment transport; is this an intentional omission? The list should be rechecked for clarity and coverage of essential variables.

The plan indicates on page A-4 that monitoring should be conducted by noninvasive means. This is an important goal, but the plan does not provide sufficient guidance for achieving it. In subsequent sections that give detailed recommendations, the plan could suggest, where appropriate, use of long-term recording instruments that would reduce the frequency of trips through the canyon, use of high-volume data loggers, use of remote sensing imagery from low-flying aircraft, automated time-lapse photography from ground stations, and extraction of data from photography by photogrammetric techniques.

The plan mentions complementary monitoring programs such as the Lake Powell studies and studies in compliance with Section 106 of the National Historic Preservation Act. While avoidance of duplication is laudable, the plan should set forth specific goals for long-term monitoring. In its present form, the plan appears to defer to other programs for the collection of critical data. The long-term data monitoring program should be self-sufficient and should use other programs only when they have the proven capacity to produce information that meets the requirements of the long-term monitoring program.

The summary of objectives for the National Park Service (NPS) indicates that the NPS is committed to management that “to the extent possible, simulates the ecosystem that existed prior to the construction of the dam.” This is inconsistent with the NPS endorsement of operating plans that involve daily fluctuation in river discharge as justified by the maintenance of hydropower revenues. Other kinds of flow regimes might more closely resemble the natural hydrograph of the Colorado River, but at the cost of reduced efficiency in hydropower marketing. While the NPS may have had good reasons to endorse fluctuating flows, its choice seems inconsistent with the statement of objectives in this section.

Later in this section (page A-5), the plan mentions the Hualapai Tribe. The plan should explain why this tribe is treated explicitly, while other tribes are treated in aggregate.

The explanation of geographic scope seems sound and well reasoned.

A geographic information system (GIS) provides an excellent basis for organizing information that is collected through long-term monitoring. It is unfortunate that the present GIS coverage does not extend over the entire reach between the Glen Canyon Dam and Lake Mead. The long-term monitoring plan should recommend completion of GIS mapping for the Colorado River between Lake Powell and Lake Mead in support of long-term monitoring.

The first paragraph on page A-7 is not clear. Presumably the zone to be included in monitoring extends at least to the elevation corresponding to a discharge of 100,000 cfs. Some rewording would clarify this.

Restriction of the long-term monitoring program to the forebay area of Lake Powell seems well justified in view of the objectives of the monitoring program.

However, sampling the forebay area on a quarterly basis will not provide sufficient information for interpretation of events in the Colorado River downstream of the Dam, nor will it create a sound basis for projection of the effects of changes in operation of the Dam. Temporal changes in Lake Powell are so large that samples must be taken at least monthly in order to provide a sound basis for interpretation.

The reference to “statistical variability” (page A-8) appears to be misplaced. The purpose of the vertical profiles is to describe the vertical structure of the water column in terms of the water quality variables that are of interest in connection with the river downstream of the Dam. It would be useful here, as in many other parts of this plan, for the monitoring requirements to be given more specifically: about how many points in the water column would be reasonable for definition of the vertical profile for Lake Powell? Similarly, would there be more than one station or just one?

The plan for monitoring of Lake Powell is unclear or insufficient in several other respects as well. For example, the plan should specify fractions of nitrogen and phosphorus to be analyzed. It is not clear why measurement of dissolved organic matter is excluded from lake monitoring, given that it is recommended for the river. The rationale for replacement of taxon-specific counts of zooplankton is not defensible because no monitoring protocol other than the enumeration of zooplankton will provide the necessary information. For phytoplankton, enumeration is important and cannot be replaced by measurement of chlorophyll a and should be reconsidered.

The monitoring plan refers to geomorphically distinct reaches on page A-9, but does not define these until later (page A-14 of the plan), and then only incidentally. The classification of Schmidt and Graf (1990) is referenced, but the reader is left with the impression that many such classifications are available. The plan must, for practical reasons, select a classification, explain it clearly and briefly, and then apply it consistently.

The plan suggests that an additional gage might be added upstream from Nankoweap Creek, but does not make a clear recommendation. The plan should recommend a specific number of gages to be used in monitoring. The opinion of the NRC committee is that no new gage needs to be added, but if the Bureau of Reclamation disagrees, the plan should clearly justify the addition of a gage. In either case, the plan should not leave this matter undecided since administrators will not be in a position to make an informed decision about inclusion of the gage.

No gaging sites should be removed, but the plan is correct in stating the National Canyon gage is the least important of existing gages. Because of its established record the committee believes that it should remain for the foreseeable future, and that the discussion of its elimination should be deleted from the draft.

The plan should make more forceful statements regarding the development of alternative sediment and water sampling at gage sites, in recognition of the fact that the National Park Service is required to manage the inner canyon as a wilderness area . The plan should specifically call for the removal of towers and cables, and the initiation of alternative sampling methods. The use of boats attached to temporary cables may be a reasonable alternative for the short term. Eye bolts embedded in the canyon walls to secure lines for use by sampling boats would be relatively small and unobtrusive alternatives to the massive structures in place now. A specific date should be established for the transition to alternate methods that will allow removal of cables.

Sediment quality is now measured at some locations on the main stem, but is not discussed in the draft long-term monitoring plan. Sediment quality is important in this system because sediment is one means by which heavy metals, radionuclides, herbicides, and pesticides move into and through the system. Suspended and bed sediments should be collected on an annual basis in a few locations (including gaging sites, the head of Lake Mead, and Lake Powell) for chemical analysis. A major surface spill into the lower Colorado River occurred on July 16, 1989 at Church Rock, New Mexico when the containment dam of a uranium mill tailings pond collapsed, releasing about 100 million gallons of mixed solids and liquids containing a variety of toxic materials, including the radionuclides thorium-230 and radium-222. In addition, the Little Colorado River passes through agricultural areas that use many pesticides and herbicides that wash into the river. Measurements at Lake Powell now show high concentrations of mercury and selenium. Many pollutants likely to affect aquatic life may be first detected in sediment rather than in water. A small number of fish tissue samples should also be assessed each year for contaminants.

According to the monitoring plan (p. A-9), modeling of sediment transport “represents a long-term alternative to continuing widespread gaging presence in Grand Canyon.” Modeling may enhance the value of empirical information, and may be important in adaptive management, but cannot substitute for collection of data. While visible field support for data collection (cableways) should be reduced, continued collection of field data on sediment transport and discharge is critical to the protection of resources in the Grand Canyon and should continue indefinitely.

The monitoring plan recommends measurement of sediment transport from tributaries to the main stem of the Colorado River. This is a sound recommendation. However, the plan specifies that the U.S. Geological Survey (USGS) collect the data. While the USGS is clearly the leading contender to perform this work, the program should not be bound to use any specific agency or group. Without the ability to direct data acquisition, the program managers will have difficulty controlling the cost and scope of monitoring.

The new plan for operating the Dam will probably include provisions for beach-building flows (controlled floods). The purpose of these flows will be to lift sand from the bed of the river to the beaches as a means of offsetting beach erosion. Although the

exact specifications of the beach-building flows are not yet evident, it is clear that such flows would need to be in excess of 30,000 cfs, and possibly considerably higher, and that they could cause substantial reconfiguration of sediment deposits. Monitoring of such events should be discussed in the plan.

The last paragraph of the section on water and sediment transport makes reference to a possible need for additional discharge data on tributaries. If this data is needed the monitoring plan should make a case for the importance of measurements on specific tributaries. Vague references to future possibilities are not appropriate in a document that must select and justify important measurements to be made over the long term.

The plan needs to be more specific about measurements of nitrogen and phosphorus. The committee believes that measurements should include total N, nitrate N, and dissolved organic N, as necessary to support estimates of total transport as well as conversion of fractions along the river. Phosphorus measurements should include particulate P, total soluble P, and soluble reactive P, for similar reasons. In addition to the variables that are mentioned in this section, chlorophyll a and algal counts should be included because they will indicate mass transport of algal biomass along the river and the species composition of the main taxa entering the river.

The plan calls for seasonal measurements of water chemistry and temperature on the main stem of the Colorado River. A major purpose of the monitoring program is to provide a basis for the assessment of change from year to year in the properties of the river. Quarterly measurements of water chemistry and temperature will be insufficient to provide a sound basis for the assessment of change from year to year because the amplitude of seasonal variation and irregular variation in critical variables is sufficiently large that the characteristics of a particular year cannot be defined on the basis of four sets of samples. The sampling frequency should be at least bimonthly and probably monthly for these variables. The same is true of measurements on tributaries that are dealt with in the following section.

Some minor changes would also improve this section of the plan: (1) the section should be retitled to include temperature, (2) a list should be included specifying all of the “recommended gages.”

Measurements at junctions of tributaries with the main stem are justified by the plan through the sensitivity of tributary junctions to changes in operations of the Dam. However, another reason for monitoring tributaries is equally important and should be brought out more explicitly. Because the main stem receives dissolved and suspended solids from tributaries and shows an interchange of organisms with them, the main stem cannot be understood without information on tributaries. Study of the largest tributaries is justified to a great extent by the need to construct a comprehensive picture of the main stem.

The end of the section on tributaries refers to other “selected tributaries.” Again, the monitoring plan needs to be specific. How many and which tributaries should be sampled? This monitoring plan is the product of an intensive assessment of monitoring requirements that included consultation with numerous experts on monitoring. If specific recommendations are not possible now on the basis of such intensive study, when will they be possible?

The opening paragraph of this section attempts to establish some connection between predictions of sediment accumulation given by the DEIS and actual accumulations that will be observed in the future under the new operating regime that is established from the Record of Decision. This explanation is not clear and convincing. To begin with, the DEIS does not really make predictions; it only gives qualitative guesses about the possible outcome of various operating regimes. In other words, almost any outcome would be generally consistent with the DEIS. The long-term monitoring program should be viewed simply as a commitment to collect information on critical environmental variables that may be affected by the operation of Glen Canyon Dam. Specific connections to the DEIS are not necessary, especially in view of the language that is given in the Grand Canyon Protection Act of 1992.

This section also makes general references to “selected campsite beaches.” How many beaches need to be monitored? How will these beaches be selected? Will the selection of beaches be reviewed periodically and, if so, how?

The plan lists “dominance and habitat requirements” as characteristics to be measured for benthic and suspended organisms near the Dam. However, dominance is not a measurement, nor is habitat suitability. What will actually be measured?

Presumably, measurements of dominance would be based on quantitative estimates of species composition, i.e., numerical information on suspended and attached organisms. Similarly, the reference to habitat requirements might imply measurements of substrate characteristics. The reference to “biotic” categories is also difficult to interpret. Are the categories ecological, phylogenetic, or something altogether different? These questions must be answered explicitly in the plan.

The plan suggests continued use of protocols from GCES II “when appropriate.” This plan is a reflection of the deliberation of experts, and should define what is appropriate or at least specify who is qualified to make that judgement.

The plan also refers in this section (page A-12) to “statistical reliability,” a reference with no definite meaning. The GCES group has been collecting samples for years. Surely at this point the group must be in a position to make specific recommendations on the number of samples to be taken, and to indicate what degree of certainty could be associated with a particular sampling strategy. Adjustments can always be made after the program begins, but a firm framework needs to be established in this plan.

The section on fishes mentions loss of trout spawning habitat which, according to the plan, “may also be of consequence.” Presumably the plan refers to the consequences of certain operational patterns, but which?

The plan states (page A-12) that pre-adult life stages are to be treated in a way that is “less complete.” This is also vague. Presented in this way, data collection on pre-adult stages seems almost incidental or casual. Specifics are needed here: in what ways will the treatment of pre-adult life stages be less complete, and why? The plan's explanations of monitoring needs should be clear enough to be followed by the many individuals outside the GCES who will review, oversee, and implement parts of the plan.

In general, there is not much discussion of what the monitoring program will accomplish besides occasional counting of fish. The United States Fish and Wildlife Service (USFWS) has expressed some reservations about operations of Glen Canyon Dam that involve daily fluctuations in flow, given that other flow regimes might provide better protection of endangered fishes. Given the breadth of informed opinion on this issue, the monitoring program should give more attention to measures of the welfare of endangered fish species.

The section dealing with trout is also disappointing. The plan seems committed in specific terms only to creel census and surveys of fishing guides. These two kinds of information, while useful and important, will provide no basis for the analysis of changes in trout populations. Growth rates, feeding habits, fish distribution, age structure, and

spawning success need to be measured directly in the field. Given the accessibility of the canyon above Lees Ferry, where the trout populations are concentrated, it would seem feasible at a reasonable cost to produce a sound set of monitoring data on trout populations.

Reference is also made in this section to a schedule of “activities” that will be determined by “resource management agencies.” As this report has repeatedly stated, the purpose of the plan is to specify monitoring requirements on the basis of an intensive review of future needs for information. The decisions that are referred to management agencies should have been made while the plan was being formulated and stated specifically in the document.

The plan appears to confuse quadrants with quadrats. This needs to be addressed. Also, there is vague reference to a “statistically significant number of sampling sites.” (page A-14) There is no such thing as a statistically significant number of sites. The plan needs to be more specific about the meaning of this phrase in this context.

The section on terrestrial vertebrates and invertebrates is inadequate. Specifically, what kinds of information should be collected over the long term on these organisms, what should be the frequency of collection, and at what sites should the data be collected? Many possibilities are left hanging. On page A-15, the plan states that information on avifauna may be available “if synthesized.” How does this relate to long-term monitoring needs? What will happen if the data are not synthesized? Similarly, monitoring of invertebrates is described in hypothetical terms, i.e., “if determined to be essential.” The committee believes that the present plan should include this determination, or specifics on how it will be made and by whom.

The section on physical sites needs to be strengthened. Reference is made to “delicate situations relative to Indian tribes,” an oblique statement that needs to be made more directly. The concerns of the tribes should not be inherently more resistant to explicit description than the concerns of any other group.

On page A-17, the plan indicates that monitoring cannot be done effectively unless baseline information is complete, but then fails to answer the question: is it complete, or will it be complete in the near future?

The plan states that “not all sites will be monitored,” but should go on to propose a specific number of sites to be monitored in each category, and outline criteria to be used in the selection of these sites.

The nature of the monitoring information to be collected at these sites is not clear. Photographs and videotapes are mentioned. Is the archive of photographic materials the only product of this portion of the monitoring program? If not, what other items will be included?

The separation of responsibilities between the National Park Service protection program and the long-term monitoring program is not clear. The long-term monitoring program should not be expected to produce all the information necessary for proper protection of sites, and this portion of the plan may be going too far in transferring NPS responsibilities to the long-term monitoring program. However, given that the number of sites is unspecified, it is difficult to tell whether this is the case or not.

This section must be augmented with more detail before it is finalized. The monitoring plan for cultural resources should indicate which resources will be monitored, how often this should occur, and what techniques will be used. Many archaeological sites along the Colorado River corridor are of low significance; monitoring should be selective. Also, care must be taken to monitor only those sites or properties that can be assessed objectively. The plan implies that historic sites are just as important as those attributed to prehistoric Indians. This is a valid and important point; historic sites along the river corridor must be given substantial weight.

Reference is made to “visitations.” This is not a scientific or technical term. Information on cultural and spiritual values and tribal concerns must be produced according to standard methodology that will be broadly useful and interpretable. There is little use for anecdotal or casual information in a long-term monitoring program. Individuals other than Native Americans may regard the river corridor as “cultural property;” their concerns should be recognized, possibly through the passive-use value studies. How will the environment be assessed on behalf of people who value the Canyon but do not use it recreationally?

The section on recreation implies that the programs now operated by various agencies will be used as sources of information. While there is no need for replication of data collection efforts, the monitoring plan needs to make commitments to the collection of particular kinds of data on recreation. Then, if an agency happens to be collecting this kind of information, and if the managers of the long-term monitoring program independently judge this information to be of appropriate quality, a transfer of information can reduce monitoring costs. However, summary transfer of responsibility to

a cluster of other agencies is not advisable. The long-term monitoring program should assume direct responsibility in perpetuity for the acquisition of specific kinds of information, and should be prepared to arrange for data collection if information from agencies that collect the data for other reasons becomes inadequate.

The collection of data on power production and economic factors is described only briefly, but appears to be limited to information that is routinely collected by the Western Area Power Administration, Bureau of Reclamation, or other parties. The plan should provide more detail on what information is needed, how often it needs to be recorded, and who is responsible for collecting it. The Bureau of Reclamation's Power Resources Committee could easily provide suggestions for the specifics.

The NRC committee previously has commented extensively on estimation of nonuse values connected with operations of Glen Canyon Dam (NRC 1992). Given the special value that is attached by the public to the Grand Canyon and its surroundings, nonuse values could prove to be an especially important element affecting judgments on alternative operations of Glen Canyon Dam. The Bureau of Reclamation has already taken important steps toward support of an expert assessment of nonuse values as part of the preparation of the DEIS on operation of Glen Canyon Dam. The current assessment of nonuse values, which are likely to evolve over time, deserves more attention in the monitoring plan. Nonuse values should be covered under a specific subheading, and should be discussed more extensively.