Note: This is a followup to Lawrence Cerrillo's column titled "Water regulations mean nothing without enforcement" posted March 23 and appearing in the print edition on March 29, 2007.

I too have been an Evergreen resident for more than 30 years. I agree with much, but not all, of what Larry Cerrillo said in his post.

Yes, water availability can be a very serious problem in the fractured crystalline rocks of the mountains, and concerns are well-founded. Furthermore, long-term sustainability of finite ground water supplies is even harder to determine than initial availability, but is the critical issue.

Larry correctly says regulations should be based on good science. I certainly agree, but Larry vaguely implies that we lack good science now, and if that was his intent, I disagree.

A perfect study is not possible for a large area in such a complex hydrogeologic regime. Doing more studies over larger areas for better results would be desirable, but would cost millions of dollars of tax money and take many years, making them impractical. In the meantime, the county needs to base land use decisions on the best science available now.

The simple fact is that the Turkey Creek study provides the best information available, based on real data, collected in the field and supplemented by historical records.

Larry implies that a 1975 report done by Hofstra and Hall is more valuable than the Turkey Creek study because it covered a larger area. However, the Turkey Creek study involved collecting far more detailed site-specific data for the specific purpose of studying ground water, including thorough studies of complex fracture systems in the study area.

The Hofstra and Hall study was excellent, but did not have access to the same resources (such as equipment to measure evapotranspiration) or data collection to go into nearly the level of detail that the Turkey Creek study did.

Even a quick review of the two reports makes this obvious. Hofstra and Hall's conclusions were largely (and necessarily) more generalized, providing general estimates that were based on reasonable assumptions more than on site-specific characteristics. Their report has held up very well as a general study, but must be superseded where more detailed data are available

Warren Hofstra was amazed and disturbed that consultants would go into County hearings on development proposals and cite the general conclusions of the Hofstra and Hall report as gospel in statements about water availability at a specific location. He always recognized that it was merely a guideline, and that it was essential to collect site-specific data and analyze it properly to assess water availability at any specific location.

Some consultants misuse the Hofstra and Hall report by presenting its generalized numbers to the county as "data" to support a clients' desired conclusion, while ignoring more specific data that do not support that conclusion. Judging by their content, many such reports may have been written without the consultant ever even visiting the site, let alone collecting data. Is this quality professional work on which land-use decisions should be made? Of course not. But, consultants who tell the county there is inadequate water to support their developer clients' plans are unlikely to be hired by those clients again. Developers tend to hire people who will tell them what they want to hear, not necessarily what they should be told.

Some local consultants have publicly excoriated the Turkey Creek report and Jeffco's proposed mountain ground water overlay district regulations. They claim their personal experience indicates the data are bad and the conclusions are wrong, but they provide no data, nor any published reports or other analysis to back up their statements.

They offer no basis to evaluate their opinions for competency or possible bias. If they want to criticize peer-reviewed published reports so strongly in the future, they should put up or shut up. Work that is based on published, unbiased, measured field data (such as the Turkey Creek study) is much more credible than a seat of the pants opinion based on general estimates that are in turn based on general assumptions. If the estimates are wrong, the conclusion is wrong. If the assumptions are wrong, the conclusion is wrong. If the general data don't apply to a specific area, the conclusion is wrong.

Another common criticism is that results from the Turkey Creek study are applicable only within its 47.2 square mile area because of regional variations in geology. Again, the Turkey Creek study does not impose conclusions for other areas, but sets a basis for what kind of hydrogeologic study needs to be done. The geologic similarities throughout the mountainous part of Jefferson County are more significant than the variations, and more than sufficient for laying a general basis for regulation. The whole point of requiring site-specific hydrogeologic studies is to compare and contrast the results with the conclusions of the Turkey Creek report (or the Hofstra and Hall report) and evaluate the local resource according to local conditions using verifiable data.

The mountain ground water overlay district regulations proposed by Jefferson County staff (before the planning commission removed several critical sections) would not impose rigid restrictions on development. Instead they would set requirements and guidelines for site-specific studies to determine local characteristics instead of just accepting general estimates based on assumptions. The regulations would set standards requiring certain data to be compiled and analyzed, to discourage cherry-picking favorable data while ignoring unfavorable data. They would require evaluation of potential harm to existing nearby wells. They also would establish an unbiased panel of experts with relevant experience, retained by the county on an as-needed basis for complex situations, to evaluate consultant reports for adequacy. That would greatly improve the quality of reports submitted to the county by developers.

Previous drafts of the regulations were strongly criticized by some people. Many critics either did not read or misunderstood the language, and repeated a false assertion that the proposed regulations would not allow development of lots smaller than twelve acres. The12-acre number never did more than define the development density for which a hydrogeologic report was required. If a competently done hydrogeologic study showed enough water was shown to be available, there would have been no size limit based on water.

Larry calls for more input by community experts to help the County craft appropriate land development regulations based on good science. Actually, he and I both served on county committees and provided such input, not always in agreement with each other. Some of our suggestions were incorporated, others were not. Neither of us was completely satisfied with the result, but we agreed at the time (or so I thought) that it was an improvement over the status quo.

I fully agree with Larry that small pre-1972 lots, many of them less than one acre, pose a very serious problem with regard to both water supply and potential contamination. Jefferson County has long been aware of this, but has done little about it. Grandfathering allows construction on sites that would otherwise never be allowed under modern health regulations. The situation poses legal and moral difficulties, but these should be outweighed by public heath considerations. Thousands of such lots exist, and the county commissioners need to develop the political will to deal with the problem realistically before continued building makes it even worse.

Larry asserts that current Jeffco health department acreage requirements for homes served by wells and leach-fields allow a reasonable argument that no new regulations or regulation revisions are needed. I disagree. He would be right if only small lots face water supply problems, but in some areas that is demonstrably not true. Until a comprehensive study allows the whole mountain area to be mapped with sustainable development densities delineated (which will not happen because of time and cost), it is uncertain which areas may have adequate water and which may not. The proposed regulations are essential to require hydrogeologic studies to evaluate specific sites. Reliance on the State is folly. The State Engineer's Office does its best, but its well permitting department is undermanned and overworked (a handful of staff processes thousands of applications annually), and lacks the resources to evaluate all development proposals to the degree necessary.

I have always argued that a conservative approach is required. If experience shows that water supplies exceed demand over time in a given area, then more development can be allowed. But if overdevelopment occurs and water turns out to be inadequate, people are seriously harmed.

You can't go into an area and tell every third homeowner that they have to move out and tear down their house so there will be enough water for the rest.

James Peterson is a professional geologist who lives in Evergreen.