The actual point where the river reaches the Sea of Cortez is a bit hard to locate.The lower Delta is very flat,and tides in the area range from 6′ (during neap tides) to almost 25′ during spring tides.Also,the change from hi tide to low tide occurs about every 6 hours.So,last Friday,at 1:30pm we had hi tide; by 7:30pm the ocean level was 22 feet lower.6 hrs later the tide was back up 22 feet higher.
When you have a very flat landscape,the tidal changes cause the water to rush back & forth up & down the channel,so that the “sea shore” moves up & down the channel many miles several times a day.
Also,in the lower delta,there is a fair amt of surface water and agricultural runoff,which will make determining exactly what is and what is not the Colorado River a bit difficult.
Finally,access to the area is a bit difficult.I’ve heard you can drive across the mud flats ...Hope to try this month!