Look, don’t touch

Diamond Valley Lake’s big, cool waters beckon the Inland Empire’s withering masses. But those antsy to take a plunge can forget it. A big keep-out sign awaits swimmers and bathers.

Don’t bother with a beach towel, fins and snorkel. Not even a toe-dip is allowed. Approved power boats, sailboats and kayaks: OK. Water skiers and personal watercraft: No.

Why? Part of the answer lies in a nearby reservoir, Lake Perris, a popular plunge plagued by chronic pollution. The source of the contamination is not industrial dumping or sewage spills, but the kidneys and bowels of thousands of swimmers and bathers who have made Lake Perris something of a cesspool. Conditions were once so bad that the lake closed its beaches for more than 100 consecutive days. The Metropolitan Water District, which provides drinking water to 18 million people, avoids using it.

The MWD is determined to keep its new reservoir drinkable. After nearly five years of study, the district’s governing board concluded the risk of pollution at the 4,500-acre Diamond Valley reservoir was too great to allow people in the water. To assuage the sweaty, there is discussion of opening two small lakes adjacent to Diamond Valley for swimmers and bathers.

“Diamond Valley would be a nightmare if you let people get in there and swim around,� said Krista Clark, regulatory affairs specialist for the Assn. of California Water Agencies. “Swimming in a reservoir is not a given right.�

Human waste contains millions of disease-causing microbes, including those that can cause dysentery-like symptoms, including abdominal cramps, nausea, severe diarrhea and dehydration. Bacteria and viruses concentrate along shallow shores and multiply as water warms. In Southern California, restrictions on body contact are in force at Lake Casitas, Lake Skinner, Lake Hemet and Lake Matthews to avoid water treatment costs.

Earthworms, salmon eggs and Stink Bait are presumably filtered out before reaching kitchen taps.